What Camera Do You Use For Photography

ClarkVision.com

Abode

Galleries

Articles

Reviews

Best Gear

Science

New

Most

Contact

Characteristics of All-time Digital Cameras and Lenses
for Nightscape, Astro, and Low Light Photography

by Roger N. Clark

---

Nighttime and astro photography requires an optimum collection of lite, because there is so piddling calorie-free available. Light collection places constraints on what to consider for nightscape and astrophotography. The principles as well utilise to low low-cal photography in general.

The Dark Photography Series:

• 001) Ideals in Night Photography
• 002) Beginning Astrophotography: Star Trails to Nightscape Photography
• 1a) Nightscape Photography with Digital Cameras
• 1b) Planning Nightscape Photography
• 1c) Characteristics of Best Digital Cameras and Lenses for Nightscape and Astro Photography (You lot ARE Here)
• 1d) Recommended Digital Cameras and Lenses for Nightscape and Astro Photography
• 1e) Nightscape Photography In The Field Setup
• 1f) A Very Portable Astrophotography, Landscape and Wildlife Photography Setup
• 2a1) Blueish Lions on the Serengeti and Natural Colors of the Nighttime Sky
• 2a2) The Colour of the Night Heaven
• 2b) The Color of Stars
• 2c) The Color of Nebulae and Interstellar Dust in the Night Sky
• 2d1) Verifying Natural Color in Night Sky Images and Understanding Good Versus Bad Post Processing
• 2d2) Colour Astrophotography and Critics
• 2e) Verifying Natural Color Astrophotography Paradigm Processing Work Flow with Low-cal Pollution
• 2f) True Color of the Trapezium in M42, The Great Nebula in Orion
• 2g) The Truthful Colour of the Pleiades Nebulosity
• 3a1) Nightscape and Astrophotography Image Processing Basic Work Menses
• 3a2) Night Photography Epitome Processing, All-time Settings and Tips
• 3a3) Astrophotography Mail Processing with RawTherapee
• 3b) Astrophotography Image Processing
• 3c) Astrophotography Epitome Processing with Lite Pollution
• 3d) Image Processing: Zeros are Valid Epitome Data
• 3e1) Image Processing: Stacking Methods Compared
• 3e2) Prototype Processing: Stacking with Master Night vs no Dark Frames
• 3f1) Advanced Image Stretching with the rnc-color-stretch Algorithm
• 3f2) Messier 8 and 20 Image Stretching with the rnc-color-stretch Algorithm
• 3f3) Messier 22 + Interstellar Grit Epitome Stretching with the rnc-color-stretch Algorithm
• 3f4) Advanced Paradigm Stretching with High Light Pollution and Gradients with the rnc-colour-stretch Algorithm
• 4a) Astrophotography and Focal Length
• 4b1) Astrophotography and Exposure
• 4b2) Exposure Time, f/ratio, Aperture Area, Sensor Size, Breakthrough Efficiency: What Controls Light Drove? Plus Calibrating Your Camera
• 4c) Aurora Photography
• 4d) Meteor Photography
• 4e) Do You lot Need a Modified Camera For Astrophotography?
• 4f) How to Photograph the Sun: Sunrise, Sunset, Eclipses
• 5) Nightscape Photography with a Barn Door Tracking Mountain
• 6a) Lighting and Protecting Your Night Vision
• 6b) Color Vision at Night
• 7a) Nighttime and Low Lite Photography with Digital Cameras (Technical)
• 7b) On-Sensor Night Current Suppression Technology
• 7c) Technology advancements for low light long exposure imaging
• 8a) Software for nightscape and astrophotographers

---

Contents

Introduction
Lens Characteristics for Gathering the Most Lite
All-time Camera Characteristics for Depression Light Photography
Crop versus Full Frame Cameras
Long Exposure Astrophotography Considerations
Discussion and Conclusions
References and Further Reading

---

All images, text and data on this site are copyrighted.
They may non exist used except by written permission from Roger N. Clark.
All rights reserved. If you lot find the data on this site useful, delight support Clarkvision and make a donation (link below).

• Recommended Cameras and My Gear List for Photography

---

Introduction

Get-go, as with all photography, the lens is the most important slice of equipment, only in low low-cal photography, gathering light is critical, especially with stars and the night sky. It becomes even more so with astrophotography to record faint subjects similar galaxies and nebulae. A nightscape prototype in natural low-cal made with a big aperture lens is shown in Effigy 1a. In this article, I'll depict the characteristics of lenses and cameras for making stunning night photos that include stars and the Milky way. I'll too discuss digital cameras and lenses for making astrophotos of galaxies, nebulae and star clusters in the deep sky. My word will exist limited to digital cameras and camera lenses, and not the many (and frequently many times more expensive) cooled CCD cameras, large telescopes, and exotic tracking systems needed to concord them. This article is nearly using wide angle to telephoto camera lenses for depression light, nightscape, and astrophotography.

Effigy 1a. Natural color epitome nightscape. Collecting light is the key to deep images like this one. The prototype is a mosaic using a Sigma 35 mm f/one.4 DG HSM lens on a full frame DSLR, a Canon 6D 20-megapixel digital photographic camera. Gallery image with more information is here.

Lens Characteristics for Gathering the Almost Low-cal

There are common misconceptions regarding lite gathering in photography. I'll offset attempt and clarify calorie-free gathering past lenses every bit it impacts the choice of lenses for dark photography.

Photographers are trained that more light gathering means a faster f-ratio. After all, exposure is direct related to the f-ratio. But f-ratio tells light density in the focal plane, not full light received from the subject. Low-cal gathering from the subject is really proportional to lens aperture expanse times exposure fourth dimension. What this means is that for greater affect with night heaven photography, buy the largest discontinuity lens yous can afford. This means the fastest f/ratio in a given focal length. Notation, this does not contradict my statement virtually f/ratio above. For example, a 15 mm f/2.8 lens has an aperture diameter of 15/2.eight = 5.4 mm, an aperture which is smaller than the dark-adapted human eye. A 35 mm f/two.8 lens has an aperture diameter of 35/2.8 = 12.v mm and collects over 5 times, (12.five/5.4)² = five.3, as much low-cal from the subject fifty-fifty though the f-ratios are the same. A 35 mm f/1.4 has an aperture diameter of 35/1.4 = 25.0 mm and collects (25/v.4)ⁱⁱ = 21 times more than lite than a 15 mm f/2.8 lens. That would exist a huge bear on in calorie-free gathering in night photography when light levels are then low.

Technical note. The lens aperture area times the subject angular surface area is chosen the Etendue. Etendue is is a cardinal parameter used in designing optical systems, including cameras for spacecraft, aircraft, lab or field use. While the term is not known in the general photography community, Etendue describes the basic physics of low-cal collection by an optical organization and is fundamental to distinguishing what is truthful from what are myths in the photography customs. Etendue is also chosen the A Omega product, where A is the lens aperture area, and Omega is the subject angular area. For example, the Moon is 1-one-half caste in diameter, then if the moon where the subject field, the subject would be almost 0.two foursquare caste, so Omega = 0.2 square caste. Etendue, combined with lens transmission, sensor breakthrough efficiency and exposure time tin be used to measure absolute lite levels with an imaging system, including digital cameras. Or it can be used to predict signal levels to set exposure times, e.g. by an orbiting spacecraft, or to compute the integration time to achieve a specific point-to-noise ratio on a galaxy with your telephoto lens and consumer digital camera.

Etendue and Light Drove. Hither is a demonstration of the above concepts. In forums almost photography there are often arguments about exposure. There commonly seems to be defoliation over brightness in an prototype and actual light drove. True low-cal collection is what is important, how many photons were collected from a subject area, because the indicate-to-dissonance ratio from a subject field in the scene is proportional to the square root of the amount of light collected. The dissonance nosotros perceive in our digital camera images is about entirely due to the noise in the lite signal itself. Brightness in an image file depends on post sensor distension (ISO). Only actual calorie-free collection (lens discontinuity expanse times exposure fourth dimension) affects the lite collection, non ISO or f-ratio. Examine Figure 1b and 1c for a sit-in. This is an extreme demonstration on purpose to illustrate light collection.

Say yous desire to make an epitome of the belt and sword region of the Constellation of Orion, including the Horsehead nebula, the Orion nebula and you have only thirty seconds to do it, and you lot can track to compensate for the World'due south rotation. You need the paradigm for a web banner. Your fastest lens is a 35 mm f/1.4 and your next fastest lens is a 200 mm f/2.8. In 30 seconds, the 35 mm f/1.four will certainly give a greater photographic exposure--a 2-terminate reward. This is illustrated in Figure 1b. The test is biased for the 35 mm f/1.4, with 2 stops greater light density and one.v times longer exposure time, the photographic exposure is certainly greater with the 35 mm image. Just was more light collected from the subject: the surface area in the white box in Effigy 1b? Does the greater photographic exposure record fainter stars and more nebulae? Photographic exposure is non the cardinal metric. The key metric for light drove is the Etendue * exposure time.

Light drove is best described by Etendue * exposure fourth dimension. Etendue is lens aperture area (technically the lens entrance pupil) times the subject area solid bending. The bailiwick can be a star, a galaxy, a bird in a tree, a person'southward face in a portrait, a person on phase in a play, or any other object we perceive in a scene. In the case of this example, the field of study is the region in the box in Figure 1b. The frame is not a subject field. The discipline solid bending can also be a fixed angular size, similar the box in Figure 1b, or a square degree or square arc-minute.

Effigy 1b. Comparing of photographic exposure with a an f/1.4 lens and an f/ii.8 lens. The box is the region of interest. In that location is a two stop difference in f-ratio and the exposure time with the slower lens is only 2/3 that of the faster lens. Which lens nerveless more than low-cal from the desired area?

From online discussions, it seems that many photographers would choose the 35 mm f/1.4 lens to make the desired image because of the greater exposure in the given time. But allow's compute which lens and exposure time collects more actual low-cal. We will ignore differences in lens transmission considering these are modest--a few to 10 or then percentage divergence. If A = lens discontinuity area, Omega = subject solid angle, and T = exposure time, the low-cal collected is A * Omega * T. Because the subject is the aforementioned with the two lenses, the relative light nerveless is simply lens aperture surface area times exposure fourth dimension, A * T. Figure 1c, panels a and b give the values of A * T. and interestingly nosotros meet that the darker exposure (past more than than ii stops) actually collected more low-cal according to the equations. Annotation: nosotros do non need to know annihilation about sensor size, pixel size or number of pixels in the camera--those parameters are not part of the Etendue equation and are not needed.

If we sum the light from the 200 mm image into the same output pixels as in the 35 mm image, we meet that in that location was actually so much light nerveless that the result is a totally saturated epitome (Figure 1c, panel c)! This a common problem in image processing, so instead of summing the light, and average is done. This prevents bravado out the image, and instead of raising the betoken also loftier, averaging pushes the racket downwardly. I can then stretch the prototype every bit desired (e.g. Figure 1d) and nosotros tin encounter more detail and fainter nebula and stars with the processed 200 mm "underexposed" paradigm compared to the 35 mm f/ane.4 image with a ii+ stops more exposure. This is because the 200 mm image collected significantly more light from the subject field.

Figure 1c. Illustration of photographic exposure compared to bodily light collection. The 35 mm f/1.4 image show greater exposure (panel a) compared to the 200 mm lens (panel b). But if we sum the light from the 200 mm prototype to friction match the 35 mm image scale, we encounter that there is so much light in the 200 mm image that the signal gets saturated (console c). Instead, we average pixels which reduces dissonance, enabling the prototype to exist stretched and testify more than detail with fainter stars and fainter nebulae (panel d). The faintest stars detected with the 35 mm lens is 12.8 versus fourteen.three for the 200 mm lens. The difference is exactly predicted Etendue * exposure time (panel e). The star in the lower right in panel east is indicated by an s and is also shown in panels a, b, and d for reference. The 35 mm f/1.iv lens as a 25 mm bore aperture and the 200 mm f/2.8 lens has a 71.4 mm bore aperture.

The ratio of the Etendue * exposure times in Figure 1c is 13.4 / 2.45 = five.v. So the 200 mm image, despite over 2 stops less photographic exposure should show fainter stars by 5.5x, or 1.viii magnitudes fainter. Indeed, the 35 mm image shows stars to nearly magnitude 12.4 and the 200 mm image to almost fourteen.half-dozen, or 1.8 magnitudes fainter (Figure 1c, panel eastward). Adding/averaging pixels together (this is called binning) reduces contrast on faint stars. The total resolution 200 mm paradigm shows even fainter stars.

Summary: lens aperture area * exposure time describes the collection of light, not photographic exposure. Let's explore these implications further.

Real-Earth Examples. Examine the images in Figures 2a and 2b, fabricated with 15 and 35 mm focal lengths with a 1.6x crop camera at f/2.8. The images illustrate 2 things. 1) One does not need really wide angle lenses (like 15 mm) every bit commonly cited every bit a requirement for Milky Way photography. Both xv and 35 mm images brand interesting nightscape images, and in my opinion, the epitome fabricated with the larger discontinuity lens, the 35 mm f/2.8 is the more interesting image. 2) The larger discontinuity diameter lens (Figure 2b) collects more than low-cal. Full pixel crops comparing fifteen mm f/2.8 versus 35 mm f/2.8 are shown in Figure 3a. Annotation the lower noise, more stars, and better item in the 35 mm f/2.eight paradigm. The 15 mm f/2.eight epitome collects likewise piddling low-cal from the night sky in a 30-second exposure. The epitome, with so niggling light, is noisier.

The images in Figures ane-3 use tracking to keep the stars round. If the camera is on a stock-still tripod then exposure times must exist reduced as focal length increases, partially reducing the advantage of the longer focal length, larger aperture lens. But as I showed in a higher place, the 35 mm f/two.8 lens collects five.2 times as much lite. On a fixed tripod, nosotros must reduce exposure proportional to the increment in focal length. Light gathering for the same f-ratio increases by the square of the focal length, and then with the reduced exposure fourth dimension for fixed tripods, we gain only equally the ratio of the focal lengths. Information technology is yet a win. And considering very wide angle lenses are not available in as fast f-ratios, one tin can gain more. For case, a 15 mm f/two.8 lens versus 35 mm f/1.4 lens (Figure 3b). The aperture expanse ratio is (25 / five.iv)² = 21 times more than light gathered. So if we tin can track, and keep exposure times the same (Figure 3b) we win big. If we must reduce exposure time by 15/35 = 0.43x, we but gain by ix.2x more light. That is still huge!

If yous go a simple star tracker, then you don't need to shorten exposure times with increasing focal length, gaining more light. Yous tin can make a simple barn door tracker (see part 5 of this series) for a few dollars, or purchase a commercial tracker, like an iOptron SkyTracker for a few hundred. Or merely stack 2 or 3 short exposures.

Now examine the images in Figure 3b and 3c, a comparison of images made with 35 mm f/ane.four and 15 mm f/two.8 lenses. Information technology is articulate that the 35 mm f/ane.four paradigm is vastly superior.

Figure 2a. The Milky Way in natural color made with a 15 mm f/2.8 lens with a i.6x ingather sensor size, 30 second exposure, ISO 1600.
Figure 2b. The Milky Manner in natural color fabricated with a 35 mm f/2.eight lens with a 1.6x crop sensor size, thirty 2d exposure, ISO 1600.
Figure 3a. Full pixel view of images from a 35 mm f/2.8 lens (left) and 15 mm f/two.viii lens (right). Natural color. Of form the image calibration is different, but note the racket in the brown star clouds. The noise is greater in the fifteen mm lens because the smaller discontinuity diameter collects less low-cal from the field of study. The 35 mm lens too records more and fainter stars in the same exposure time.
Effigy 3b. Full pixel view of images from a 35 mm f/1.4 lens (left) and 15 mm f/2.viii lens (right). Natural color. Of class the prototype scale is different, merely note the noise in the brown star clouds. The racket is greater in the fifteen mm lens because the smaller aperture diameter collects less calorie-free from the subject. The 35 mm lens besides records more and fainter stars. The 35 mm lens collects over 21 times as much light in the same exposure time.

If you want tp make images of the Milky Fashion presented so that the field of study is the aforementioned size, as in the Galaxy appears the aforementioned size on a print or screen, The image made with the longer focal length needs to exist resampled and the larger discontinuity, longer focal length lens produces the better prototype. I prove the effect of resampling the larger focal length lens to have the same amount of pixels on the subject in Figure 3c. Of course, for the same total field of view coverage, one would demand to make a mosaic with the longer focal length. Prints made from the wide angle lens versus a mosaic with a large aperture longer focal length bear witness a stunning difference (Figure 3c). Here we run into the effect of racket on the subject, the Galaxy. The 15 mm f/two.viii prototype shows a lot of racket. The noise masks many faint stars, and the noise reduces contrast between the brighter dust clouds and the dark clouds in the Galaxy. The 35 mm f/ii.8 paradigm shows fainter stars than the 15 mm f/2.8 showing that you practise not go the same corporeality of lite with the same f/ratio. The 35 mm f/1.four image shows very little noise, increased contrast and fainter stars and produces the overall best epitome of the 3 shown.

Figure 3c. The images from Figures 2a, 2b, 3a, 3b resampled to the same pixels on subject as the 15 mm image. Natural colour. On the aforementioned calibration, the larger aperture lens produces the improve image with lower noise, finer detail, and fainter stars. The 15 mm image is and so noisy, the noise looks like stars, and people often complain that their images show also many stars when information technology is really the noise in their images made with pocket-sized apertures. The 35 mm f/i.4 image (right) is less busy, with less noise and the number of stars looks more balanced. The box in the right two panels indicates where the Signal-to-Dissonance ratio (S/Due north) measurement was made. We would await an improvement of 2.3x and the measured improvement is 2.5x for the 35 mm f/2.viii lens over the fifteen mm f/2.8 lens. The 35 mm f/one.4 image has a higher Southward/Due north by another gene of two and shows real detail at fine scales not seen in the other ii images.

The Mosaic Advantage. Every bit shown in Figure 3c, mosaicking with a larger aperture longer focal length lens has an advantage regarding noise and detail. Only it goes farther. Some images fabricated with mosaics are difficult to incommunicable with broad angle lenses if i wants to tape the same faint particular. For instance, the paradigm in Effigy one covers 88 past 85 degrees and is a 31 frame mosaic made with a 35 mm f/1.iv lens on a total frame camera. A xiv mm lens, available in f/2.8 would virtually cover the width (81 degrees). The Effigy 1 prototype used nineteen 30 2d exposures for the heaven and 4 positions on the land, stacking 3 120-second exposures (6 minutes for the land). A 14 mm lens has an aperture of 14/two.viii = five.0 mm compared to the 25 mm aperture diameter for the 35 mm f/one.4 lens. The 35 mm lens collects 25 times the amount of light. On the sky, the 14 mm lens would need an exposure of 12.5 minutes. Simply the stars are moving, some rise on the left, and setting on the correct, and stars are going behind and emerging from the mount peaks. Thus ane nevertheless needs multiple exposures. to assemble a reasonable view in time of the stars in the heaven. For the land, a 6*25 = 150 infinitesimal exposure would be needed! Thus, the 14 mm image would take over three hours to gather the aforementioned amount of low-cal from the scene. The 35 mm image can be done in under one 60 minutes. Farther, I do the horizon line get-go to minimize star motion relative to the land, making final assembly relatively simpler. This image of the Maroon Bells with water reflection would be incommunicable to practice with a wide angle lens similar xiv mm f/2.8 and get the same signal-to-noise ratio equally with a 35 mm f/1.4 lens. The long exposure times would mean one could non line up the stars in the heaven with the reflection because multiple 12.5 minute exposures would be needed on both the sky and reflection and the stars motion also much in this case. With wide bending lenses, one is forced to continue full exposure time lower, thus making a noisier image, fewer stars and lower impact.

Figure 4 shows examples of details in deep sky objects made with a 35 mm f/1.4 lens on a full frame DSLR (Canon 6D). Figure 4 shows total resolution particular y'all tin can get with a 35 mm f/1.4 lens and tracking/stacking several exposures. Detail includes screw artillery in galaxies, stars in star clusters and shapes of emission nebulae.

Effigy iv. Full pixel resolution images made with a 35 mm f/one.4 lens and Canon 6D camera (vi.iv micron pixels). Natural color. Note the dark lanes in M31, the spiral arms of M33, the blue dust in M45, individual stars in the Double Cluster, and the shapes of the Centre and Soul nebulae. Shorter focal length lenses do non resolve such details. The red background in some images is due to airglow and aurora. The images were made using a Sigma 35 mm f/1.four DG HSM lens on a full frame DSLR, a Canon 6D 20-megapixel digital camera.
Gallery image with more information is here.

You can practise nightscape images with longer focal lengths too, for example, every bit shown in Figure v. Longer focal lengths, fifty-fifty with mosaics, mean a smaller field of view, and more precise planning of location and the times when interesting stars are above the landscape are required. But the results can accept incredible detail. Note, the mountain in Figure 5 is the same mountain as in Figure i.

Figure v. Mosaic of images made with a Canon EF 100mm f/2 USM Lens lens on a one.3x ingather photographic camera. Natural color. This illustrates ane can make stunning nightscape images with whatever focal length, not but wide angle. The green sky is from airglow. Gallery prototype with more information is here.

All-time Camera Characteristics for Low Calorie-free Photography

Summary Regarding Selecting a camera

• Digital cameras go along to amend fifty-fifty over the last few years. Central improvements include better Quantum Efficiency (QE), lower noise floor, lower nighttime current, meliorate low signal uniformity, and lower pattern noise.
• Avoid cameras that filter raw data. Variations in filtered raw information vary from deleting stars to turning star color to green or magenta (in that location are no green or magenta stars). For a partial list of photographic camera models known to filter raw data encounter the links in this folio: Image Quality and Filtered Raw Data.
• Large vs small pixels. Online 1 frequently sees the myth that larger pixels are more sensitive. However, adding betoken from multiple small pixels to course a larger pixel gives about the same total bespeak equally a large pixel of the same area. Cameras with large pixels tend to show more pattern dissonance, due east.g. banding. College megapixel cameras, especially recent models, which have smaller pixels, tend to have less design noise and better low cease uniformity.
• Mirrorless cameras and shutters. Choose camera models with a shutter. If there is no shutter, the sensor is exposed and will attract grit. I take many cameras, including Canon 7D. 7D Mark II, 6D, 6D Mark II (two bodies), 90D and R5. All take shutters and I accept never one time had to make clean whatever of the sensors. Several cameras take been multiple times to the dusty Serengeti and other locations around the world, and never a grit problem.
• Choose models that take a self-cleaning sensor unit of measurement (ultrasonic vibration of the filters over the sensor). Set up up the camera to automatically make clean the sensor when it is turned on or off. Run the cleaning process before a long imaging session. Minimize the time the camera is exposed with no lens or body cap on. For example: Minimize Grit Contamination.
• Circa 2008 a new pixel pattern started to exist introduced in consumer digital cameras that reduced the effects of dark current. It is chosen On-Sensor Night Electric current Suppression Engineering science. In ameliorate implementations the so-called amp glow seen in long exposures is gone and astrophotographers no longer need to take dark frames considering the dark current is measured and removed in hardware in the pixel during the exposure on your subject field. Circa 2014 the engineering science was getting pretty expert, so if ownership a used camera, select models produced after near 2013, but even more contempo models show improvements.
• Random noise from dark current is even so an outcome (the dark current suppression technology blocks accumulating signal levels (e.g. amp glow and offsets), but not random noise. Then finding a low dark current camera is important for amend performance. But also important is keeping the camera from heating upwards. Dark current doubles every increase of 5 to 6 degrees Centigrade, then random noise doubles every 10 to 12 degrees Centigrade. One trend that is actualization is that cameras with flip-out LCD screens move a heat source and mass away from the sensor, then the camera may run cooler and/or not oestrus upwards as much as models with no movable LCD, thus the random noise from night electric current may be lower. The flip-out LCD screen helps with viewing in unusual positions too.
• Camera models from the last two or iii years evidence significant improvements over earlier models and have improve low calorie-free uniformity, depression dark electric current, excellent dark current suppression technology and more models with flip-out screens to better misemploy heat. Mirrorless and DSLR models that practise high charge per unit 4K video may too have improved heat dissipation.
• Lesser line is to buy the most recent camera models you can afford. Many are fantabulous for astrophotography as well as regular daytime photography, and sports and wildlife photography.

Details

Contrary to popular internet opinion, the primary cistron, after lens aperture in long exposure photography, e.g. virtually a minute and longer, or even tens of seconds in warm environments, is noise from dark electric current. Pop internet stance focuses on read noise, but read dissonance is insignificant in long exposures compared to noise from lite pollution, airglow, and dark current, peculiarly when used with lenses faster than about f/4. One tin but beat light pollution in full colour imaging by imaging the night heaven far from cities, but dark current goes with the photographic camera. Dark current is very camera dependent, and few reviews measure it. Nighttime electric current is measured in many reviews here on Clarkvision.

Depression dark electric current is a key cistron in long exposure low light photography. First some facts almost dark current. Dark electric current doubles every few degrees increase in temperature. Typically, the doubling in CMOS sensors is every five to six degrees Centigrade. To be really precise with dark current subtraction (used in astrophotography), one needs the nighttime current to be measured at the same temperature to within a fraction of a degree. Noise from night current is the foursquare root of the dark current from the total exposure fourth dimension (including stacking) and is independent of sub-exposure times. For example, if you make fifty 1-infinitesimal exposures using a camera with 1 electron/2d dark current, the noise from nighttime electric current in the stacked image is foursquare root ( 50 exposures * lx seconds per infinitesimal *1 minute) = 55 electrons.

Another big factor in image quality in nightscape and astrophoto images is banding in the camera. Banding is a stock-still design usually horizontal and/or vertical. We are very sensitive to detecting banding so it becomes objectionable even when the peak-to-peak banding is ten times smaller than random racket in the image. Some cameras have banding problems at some ISOs and not others. As ISO is increased, banding problems usually decrease. Banding is shown in reviews here on Clarkvision.

In that location is ane camera that I take tested or seen information from other testing that stands well higher up the others: that is the Canon 7D Marker Ii digital photographic camera (Figure 6, beneath). Encounter the 7D Mark Ii review here and wait at Figure iii and Table iii of the review and the corresponding word. Some recent Sony and Nikon numbers by people on dpreview indicate dark currents similar or slightly ameliorate than the other Canon cameras on Figure half-dozen below but I have not seen any data better than that for the 7D2.

Figure half dozen. Dark current for several cameras is compared as a function of internal camera temperature. Note the amazing improvement in depression nighttime current with the Canon 7D Mark II digital photographic camera. Sony sensor data are from commercial data sheets found online.

Newer model cameras from all manufacturers generally take ameliorate sensors, with lower noise (banding, read noise, dark electric current), so choose the latest model cameras for all-time results, particularly if they accept reviews that show if the camera has banding problems and a measurement of dark current.

Key new technology is called dark current suppression. Dark electric current suppression technology is hardware and part of the pixel design. It is non something your turn on or off in software. It is not long exposure racket reduction. It is not high ISO dissonance reduction. The hardware in the latest sensors use a four-transistor circuit in the pixel. Some use 3 transistors. This is called 4T and 3T designs. What nighttime current suppression engineering science does is block the bespeak, but not the dissonance from night current. The engineering became established in circa 2008 digital camera models, and has been refined with newer models. What this ways is in sensors that have the technology, we do not need to mensurate dark frames and decrease them in post processing. We no longer see amp glow in long exposure images (usually seen equally pink blobs on the edges of frames). This technology allows a big simplification in post processing. If your camera shows amp glow, information technology would exist a benefit to upgrade to a newer photographic camera (models post circa 2008). The newest models generally take better refinements, meaning longer and longer exposures without the problems then common in older models. Figure 7 shows the major accelerate in engineering science that dark suppression and other sensor improvements accept enabled in the concluding decade. If y'all have an older camera, pre 2010 and certainly pre 2008, an upgrade to a very contempo model tin be a large benefit. Encounter Part 7b) On-Sensor Nighttime Current Suppression Technology of this serial for more detail.

Effigy 7. Comparing of engineering. The paradigm on the left was obtained in 2005 and on the correct 2015. The prototype on the right collected 36% more calorie-free per pixel, and then if technology were equal, the credible dissonance difference would exist only about 17%, barely noticeable. Plainly, the improved sensitivity and lower dissonance of modern cameras makes a huge difference. See the gallery image of the 2015 image here. The 2015 image was made with a Canon 7D Marking Ii 20-megapixel digital camera and 300 mm f/two.8 L IS 2 lens plus a Canon Extender EF 1.4X 3 giving 420 mm at f/4 and ISO 1600.

Some other thing to consider in selecting cameras with low dark current (think, the dark electric current suppression technology blocks the night current level, just not the noise), is camera models that will dissipate heat more efficiently. The big massive pro cameras are at a disadvantage here. Their shear mass, by and large faster electronics, more electronics (e.g. dual cpus), mean more estrus and the oestrus that gets generated is harder to dissipate with all that mass. Lighter smaller cameras tend to dissipate heat improve, and with slower electronics, generate less estrus.

Only regardless of new camera, you volition see the biggest impact on image quality past getting quality lenses with larger apertures. For instance, 24 mm f/ane.iv, 35 mm f/1.4, 50 mm f/ane.iv. The Sigma Art serial are fantabulous. Rokinon/Samyang are cheaper but be enlightened people are finding they need to return multiple lenses before getting a good re-create.

Crop versus Total Frame Cameras

Opposite to popular net belief, larger sensor cameras have little to exercise with sensitivity. We ofttimes read on the internet that full frame cameras are more sensitive and that they are better at low light photography. This is a misunderstanding of the light gathering of lens and sensor. A larger format ENABLES ane to use a larger lens. It is the lens that collects the light ; the sensor is but a bucket to collect the light delivered past the lens (Figure eight).

Effigy 8. Raindrops (blue) every bit an analogy to photons entering a camera. The buckets ("pixels") fill with water (blue), merely the orange funnels (the lens) collect the pelting and focus it onto the buckets (pixels). In this case the large finish of the funnels have the same diameter so collect the same amount of rain per unit of measurement fourth dimension (the exposure). The ONLY difference is the small saucepan volition fill upwards faster, only that is not a problem in low light situations. Modest buckets are Non a disadvantage. The funnel diameter controls how much rain goes into the bucket, not the size of the bucket. It is the aforementioned with cameras, lenses, and pixels. The angle "a" is the is the angular size of a pixel and is the same for both the big and modest pixel in this example. In a camera, both cameras would become the same amount of light per pixel, testify the same noise, take the same pixels on the subject, and take the same depth of field.

Example. For a given field of view, e.g. a 35 mm on a full frame sensor gives a 54.4 by 37.8 degree field of view. To get that same field of view on a 1.6x ingather camera, one needs a (35 / ane.6 =) 21.87 mm focal length lens. Say the 35 mm lens was f/2.viii, with an discontinuity diameter (35 / ii.8 ) = 12.5 mm. To collect the aforementioned amount of light with the 21.87 mm lens on the crop camera, it would demand the same aperture diameter (technically called the entrance pupil) of 12.5 mm, making an f-ratio of 21.87 / 12.5 = ane.75. Typically, photographers proceed the f-ratio constant, thus compare a 35 mm f/2.8 on the full frame to 21.87 mm f/2.eight on the crop. But a 21.87 mm f/2.eight lens has a smaller diameter discontinuity (21.87 / 2.8 =) 7.eight mm, and collects 2.5 times less light from the subject (12.5/seven.8 squared)! The f-ratio tells lite density, NOT total lite from the bailiwick. This concept seems particularly confusing to photographers trained that f/ratio tells nearly light. Yes, f-ratio tells light density thus exposure, but not total low-cal from the subject. If yous don't believe this, run across Figures 9a, 9b and the text below, or if y'all want to larn more than run into part 1a of this series with Figures 4a, 4b, 5a, 5b and my series on Understanding Exposure.

Here is some other mode to look at the problem. Retrieve of information technology this way: yous have a full frame camera and after you take the paradigm, you lot crop the paradigm. Yous changed the field of view. You did not change the actual focal length. A ingather sensor is merely a smaller sensor--recall of information technology as full frame pre-cropped so you don't have to crop in postal service processing. It does not alter the lens fastened in any mode--the focal length is the same. The aperture is the same. The corporeality of lite gathered within the frame is the same. The smaller sensor just means a smaller field of view. Why people retrieve that changes sensitivity is surprising.

To empathize issue of sensor size, effort this analogy, we both go to a hardware store, You buy a 5-gallon bucket, I buy a i-gallon bucket. Nosotros then get to a water faucet that is dribbling a low rate of water and make full our buckets for xxx seconds. How much water do nosotros each have in our buckets? The amount of water in our buckets is not dependent on the bucket size unless i bucket overflows, and with the low rate of water from the faucet, neither saucepan overfills (analogy to depression calorie-free photography). The corporeality of h2o in the saucepan is dependent entirely on the faucet delivering the water (illustration to the photographic camera lens) and the length of time of the fill up (the exposure fourth dimension). The amount of water in the saucepan has nothing to do with bucket chapters. Nosotros have the same amounts of water in our buckets. It is the aforementioned with pixels: the amount of light captured in the pixel is dependent on the lens delivering the light. At that place is 1 additional factor in cameras and lenses: the area the pixel covers. If we equalize the expanse, and thus pixels on discipline, then using the same lens, same f/ratio, same exposure time, the light per pixel is the same, as in Figure 9a.

The lens delivers the light. The pixel is just a saucepan. Beneath in Figures 9a, and 9b are comparisons of images fabricated with a full frame and i.6x ingather cameras. If we believed the internet myth that larger sensors are more sensitive, one would look to encounter fainter stars in the paradigm fabricated with the larger sensor and a noise difference between full frame and crop cameras to be the foursquare root of the pixel areas, or sqrt(two.59) = i.6, which would make the crop camera image noticeably noisier. Clearly, that is not the example in Figure 9a. Web sites that prove a differences between ingather and full frame cameras are typically changing the lens aperture surface area betwixt cameras, thus the corporeality of calorie-free collected. If we go on the camera with small pixels at its full resolution and enlarge the prototype from the camera with the larger pixels, equally in Effigy 9b, we do meet that the small pixels are noisier per pixel, merely in that location are more pixels in the same area as a pixel from the larger pixel photographic camera, thus the photographic camera with smaller pixels show effectively noise, and more than detail. And because the pixels are smaller, the stars are smaller, and there is less contribution of noise from heaven glow and dark electric current, so the camera with smaller pixels shows essentially fainter stars.

Figure 9a. Comparison of images made with a total frame and ane.6x ingather cameras. The ratio of the pixel areas is 2.59. Focusing on the subject, not the pixel (after all what is the subject in a photo: the bailiwick, or the pixel?), I binned the smaller pixels of the 1.6x crop camera to the same pixels on subject in the full frame. By resampling to the aforementioned pixel on the subject, we see that the indicate-to-noise ratio (Southward/North) is essentially the same in the uniform areas (agreement to better than ane percentage), simply the smaller pixels of the crop camera actually record fainter stars and more item, even afterward resampling. Compare the unbinned images in Effigy 9b.
Figure 9b. Comparing of images from two cameras--the same as in Figure 9a, simply the crop sensor image is shown at full resolution, and the full frame camera enlarged 1.6x for comparison. The smaller pixels on the crop camera record fainter stars, over 70% fainter (0.6 magnitude). The noise per pixel is higher in the crop sensor camera, only in that location are more pixels, so the racket appears smaller. In that location is also more fine detail in the ingather sensor camera image, thus providing better overall image quality despite technically having more noise per pixel. And equally shown in Figure 9a, when the pixel angular areas are normalized, the noise is basically the same.

You can brand not bad nightscapes and great astrophotos with both cropped sensors and full frame sensors. I accept made nightscape and astrophoto images with both cropped and full frame cameras. My preferred astrophotography camera when I am doing many minutes of exposure is a camera with low dark current, regardless of sensor size. I pay less attention to sensor size in choosing a camera for a low light job, and pay more attention to sensor characteristics like low dark electric current and the lens that I volition use.

The only other cistron to consider regarding cameras is being able to change lenses. Very fast broad angle lenses are only available in single focal lengths (commonly known every bit prime lenses) with simply a few rare exceptions. Virtually zoom lenses are not as fast and produce lower quality star images (again there are some exceptions). This mostly ways a DSLR or mirrorless photographic camera with interchangeable lenses. Note that also much use of alive view, whether mirrorless camera or DSLR heats the sensor increasing dark current noise. Thus I prefer DSLRs because I can frame and use the optical viewfinder to minimize sensor heating. Once a sensor heats upwardly, it can take a half 60 minutes or more than to absurd dorsum to ambient temperatures.

Long Exposure Astrophotography Considerations

Astrophotography with uncooled digital cameras has specific challenges. As discussed above, night current can be pregnant, and when imaging in a low lite pollution dark surroundings, dark current is usually the limiting factor in imaging faint objects. Second, the lite from galaxies, nebulae and others interesting objects in the deep heaven is very faint. That ways the largest aperture are yous can put to work is important. Nighttime current scales with pixel size, significant larger pixels accept more nighttime current than smaller pixels.

This leads to the non-intuitive concept of using the largest aperture to concentrate the low-cal onto the smallest pixels!

Figure ten. The Whirlpool Galaxy, M51. This paradigm was obtained with a Catechism 7D Mark II 20-megapixel digital camera, a photographic camera with small pixels and 300 mm f/ii.8 L IS Ii lens plus a Catechism Extender EF one.4X III giving 420 mm at f/4, ISO 3200 and 2-arc-seconds per pixel. Gallery image and more than data is here. Image scale is ii arc-seconds per pixel.

Pixel Size. As I have already discussed, sensor size has piddling to do with collecting light from the subject. Similarly, pixel size also has little to practise with light collection. The quantum efficiency (QE) per square mm is the same (for the aforementioned technology) whether a tiny sensor in a cell phone photographic camera, or a full frame DSLR. This ways if yous concentrate the same amount of lite onto a spot x microns foursquare versus v microns square, the aforementioned proportion of light will exist captured by the sensor. But considering smaller pixels have less dark current, a system with smaller pixels can in do perform meliorate at depression light long exposure photography.

For example, consider a 600 mm f/5.six lens with a digital camera having 8 micron pixels. Telephone call this System A. The angular size of one pixel is 2.75 arc-seconds (this is called the plate scale). The lens bore is 600/v.six = 107 mm. Consider a second system, System B, with a 300 mm f/ii.eight lens and a digital camera with 4-micron pixels. Organisation B has the same lens diameter (300/two.8=) 107 mm, and the same plate scale of 2.75 arc-seconds per pixel. The lens in Systems A and B will each deliver the same amount of low-cal to the pixel. Bold the image quality of the ii lenses is the same, both will produce equal images in the same exposure time, EXCEPT in long exposures where noise from dark current is a cistron (deep space astrophotography). This is where the smaller pixels take an advantage.

The next thing to consider in astrophotography is plate scale for imaging different deep space objects. A few objects are quite large, like the Great Nebula in Orion, M31, which is near double the bore of the full Moon, the the Andromeda galaxy, M31, which is over eight times wider than the full Moon. There are likewise some larger structures of the Milky way that can be imaged by shorter focal length lenses. There are also many smaller objects, including galaxies and nebulae, which require finer resolution to get much particular in them. But atmospheric turbulence limits resolution in almost cases except in rare circumstances. Long exposure astrophotography is oft limited to about two arc-seconds. The epitome in Figure 10 is at ii-arc-seconds per pixel and if you follow the link to the gallery prototype, yous will see a larger image at 1.5 arc-seconds per pixel. See; Astrophotography and Focal Length: What Tin can Yous Image with Various Lenses? for more than examples.

For deep sky astrophotography, I commonly choose lens and sensor to give between i and 4 arc-seconds per pixel depending on the size of the object. For nightscapes, it can be more than about field of view and larger structures, so plate scales in the tens of arc-seconds per pixel are chosen. A 200 mm lens on a camera with 4 micron pixels gives four.1 arc-seconds per pixel, and 800 mm gives 1 arc-second per pixel. See plate scale for scales with specific cameras and lenses. Run into Lens Field of View for data on camera sensor sizes and lenses.

Discussion and Conclusions

Putting the above information together, the ideal astrophotography system is very fast lenses feeding cameras with small pixels for a given plate scale. As with nightscape photography, where lenses like 24 mm f/1.4 and 35 mm f/1.4 are ideal, moving up the athwart resolution range, 50 mm f/1.4, 85 mm f/1.4, 100 mm f/ii, 135 mm f/2, 200 mm f/2 or f/2.8, 300 mm f/2.viii, 400 mm f/2.8, 500 mm f/iv feeding digital cameras with pixel sizes around 4 microns are platonic.

Wide angle lenses, similar fifteen mm f/two.8 can make for easy night sky images. But the pocket-size apertures hateful little light is gathered. A 15 mm f/2.8 has a smaller aperture diameter (5.4 mm) than the night adapted human being heart (most seven mm). The picayune light gathered past such lenses results in a lot of dissonance in the typical twenty to 30 second exposures typical washed by nightscape photographers. That noise is confused with stars leading people to retrieve they have as well many stars in their images. Larger aperture lenses, like 24 mm f/one.4, 35 mm f/one.4 collect many times more light, producing images with less racket. The less noise shows faint stars amend, making for a improve balance of stars and Galaxy clouds (run into Effigy 3c). Mosaics made with these larger aperture lenses make cleaner images with more detail, higher contrast and greater impact.

Another take-home message from this commodity and the physics: use the largest aperture lens/telescope to collect the almost light. Efficiency may mean doing a mosaic depending on available resource of lens aperture size, focal lengths and fields of view. One can compromise on the lens for simplicity (east.g. ultra-wide lens and single curt exposure versus mosaic with a larger aperture lens), but that simplicity reduces light collection, increasing credible racket and resolution. This is true for daytime as well as nighttime photography--the physics does not change, only in daytime photography there is generally more light so the compromise may result in an acceptable image.

Run into Recommended Cameras and My Gear Listing for Photography for specific cameras and lenses that I utilise, and watch here for recommendations of the best cameras and lenses for night and astrophotography for Canon, Nikon and other manufacturers.

Technical. The technical term for the above concept of lens aperture collects the light and the field of view of the pixel is called the Etendue. It is the key property of imaging systems. See my series on Understanding Exposure for more than information.

---

If you detect the information on this site useful, please support Clarkvision and make a donation (link below).

• Recommended Cameras and My Gear Listing for Photography

---

References and Farther Reading

Clarkvision.com Nightscapes Gallery.

Clarkvision.com Astrophoto Gallery.

---

The Night Photography Series:

• 001) Ideals in Dark Photography
• 002) Commencement Astrophotography: Star Trails to Nightscape Photography
• 1a) Nightscape Photography with Digital Cameras
• 1b) Planning Nightscape Photography
• 1c) Characteristics of Best Digital Cameras and Lenses for Nightscape and Astro Photography (YOU ARE HERE)
• 1d) Recommended Digital Cameras and Lenses for Nightscape and Astro Photography
• 1e) Nightscape Photography In The Field Setup
• 1f) A Very Portable Astrophotography, Landscape and Wildlife Photography Setup
• 2a1) Blue Lions on the Serengeti and Natural Colors of the Night Sky
• 2a2) The Color of the Night Sky
• 2b) The Color of Stars
• 2c) The Colour of Nebulae and Interstellar Dust in the Night Sky
• 2d1) Verifying Natural Color in Night Sky Images and Agreement Good Versus Bad Post Processing
• 2d2) Color Astrophotography and Critics
• 2e) Verifying Natural Colour Astrophotography Image Processing Work Flow with Light Pollution
• 2f) Truthful Color of the Trapezium in M42, The Great Nebula in Orion
• 2g) The True Color of the Pleiades Nebulosity
• 3a1) Nightscape and Astrophotography Image Processing Basic Piece of work Flow
• 3a2) Dark Photography Prototype Processing, Best Settings and Tips
• 3a3) Astrophotography Mail Processing with RawTherapee
• 3b) Astrophotography Image Processing
• 3c) Astrophotography Image Processing with Light Pollution
• 3d) Image Processing: Zeros are Valid Image Information
• 3e1) Image Processing: Stacking Methods Compared
• 3e2) Prototype Processing: Stacking with Master Night vs no Dark Frames
• 3f1) Advanced Image Stretching with the rnc-color-stretch Algorithm
• 3f2) Messier 8 and 20 Paradigm Stretching with the rnc-color-stretch Algorithm
• 3f3) Messier 22 + Interstellar Grit Image Stretching with the rnc-color-stretch Algorithm
• 3f4) Advanced Image Stretching with High Low-cal Pollution and Gradients with the rnc-color-stretch Algorithm
• 4a) Astrophotography and Focal Length
• 4b1) Astrophotography and Exposure
• 4b2) Exposure Time, f/ratio, Aperture Area, Sensor Size, Quantum Efficiency: What Controls Calorie-free Collection? Plus Calibrating Your Camera
• 4c) Aurora Photography
• 4d) Falling star Photography
• 4e) Do Yous Demand a Modified Photographic camera For Astrophotography?
• 4f) How to Photograph the Sunday: Sunrise, Sunset, Eclipses
• 5) Nightscape Photography with a Barn Door Tracking Mount
• 6a) Lighting and Protecting Your Night Vision
• 6b) Colour Vision at Night
• 7a) Night and Low Light Photography with Digital Cameras (Technical)
• 7b) On-Sensor Dark Current Suppression Technology
• 7c) Engineering science advancements for depression light long exposure imaging
• 8a) Software for nightscape and astrophotographers

---

Dwelling house

Galleries

Manufactures

Reviews

All-time Gear

Science

New

About

Contact

http://www.clarkvision.com/articles/characteristics-of-best-cameras-and-lenses-for-nightscape-astro-photography

First Published March fourteen, 2016
Last updated Jan 22, 2021

Source: https://clarkvision.com/articles/characteristics-of-best-cameras-and-lenses-for-nightscape-astro-photography/

Posted by: handylocatell.blogspot.com

Share this post