Review Canon 10D
for Deepsky astroimaging

Updated: Nov 20, 2004

After owning the D60 for one year I decided to exchange it against the new 10D model.
The main reason for this decision has been the better noise behavior during long exposures of the 10D compared to the previous D60.

Some other short cuts of the D60 have been improved too:
* nearly complete elimination of the red amplifier glow at the right side of the image;
* higher ISO settings up to 1600 (3200 not really usable);
* higher review magnification of up to 10x for analyzing images via the internal display;
* improved remote capture software allows multiple interval exposures each max 30 sec (but no bulb mode!);

The newer cheaper Canon Rebel (300D in Europe) supplied in a plastic case shows similar results for deep sky applications, 2 major drawbacks: no mirror lockup, no connection to remote interval timer posssible, however the mirror lock-up function and some additional customs settings can be achieved with a hacked firmware update (makes warranty void!), checkout details: here

The new successor of the 10D is the 20D with 8 MP, find a comparison of the 2 models from Christian Buil: here.

The Canon 10D like the previous D60 uses the same 22.7 x 15.1 mm 6.3 megapixel CMOS sensor (3072 x 2048 final image size)

The sensor resolves 12 bit per channel that can be converted by a raw image converter to 16 bit per channel tiff format.

The SLR type body enables optimum coupling of any telescope (usually at prime focus)
When adapting lenses of other brands one should note that the distance from the Canon bajonet (EOS film and EOS digital) to the focal plane is 43,5 mm, from a M42 ring it is 45 mm.

Compared to film for any lens the focal lenght has to be multiplied with the factor 1.6

Used and highly recommended accessory: remote control interval timer TC80N3, right angle viewfinder, second battery pack;
The Remote Capture software is included by Canon;

A general review of the 10D you find: here

10D spectral sensitivity charts you find: here (C. Buil)

An astro related comparison of the Canon 10D with the Nikon D70 again from C. Buil you find here.

A noise comparison of the 20D to the 10D again from C. Buil you find: here.

A nice comparison of the noise at different ISO rating versus exposure time and temperature was done by:
Roger N Clarke (link)

A collection of useful information about use of the Rebel for DSOs including IR filter removal has been published by:
Terry Lovejoy (link)

Find my setup of the 10D: here (at bottom of that page)

What I am still missing:
* multiple bulb exposures with remote capture software without parallel port
* quick subframe center readout (for focusing and planetary imaging)



Test shots Canon 10D

Dark comparison Canon D60 to several Canon 10D

300 sec at ISO 800 at +22°C in jpg-fine, WB-auto

The image at right shows 4 darks (vertically cropped, no stretch) from different camera models at 50% size:
Top: my 10D at 26C (serial 0620...)
next: an older 10D (serial 0320...)
next: a newer 10D (serial 0420...)
Bottom: My old D60

The comparison shows that the amplifier glowing from the D60 has been completely eliminated for the 10D; the uniform noise is bad for the 0320... model, most of the newer 10D models are showing significantly lower noise than the D60 models for bulb exposures.
ATTENTION: also some newer models show high noise, so a comparison test at the shop is recommended, use ISO1600 and 300 sec bulb exposure with the cap on for comparison and check the histogramm.
The major part of this residual noise can be subtracted by taking dark frames.

(113 kB)

Noise at different ISO ratings
All images are 300 sec darks (center crops) at 22°C in jpg-fine, WB-auto

statistics (Astroart):
background: 0
average: 0.67 0.86

clic for full size (27 kB)

statistics (Astroart):
background: 1
average: 0.90 1.05

clic for full size (35 kB)

statistics (Astroart):
background: 2
average: 1.57 1.38

clic for full size (44 kB)

statistics (Astroart):
background: 2
average: 2.14 2.20

clic for full size (43 kB)

statistics (Astroart):
background: 1
average: 2.66 5.20

clic for full size (35 kB)

Dark frame comparison animation

The above darks have been stretched to give all the same light efficiency:
ISO100 multiplied x 16: average 11.8 11.5
ISO200 multiplied x 8: average 7.5 7.2
ISO400 multiplied x 4: average 6.2 5.0
ISO800 multiplied x 2: average 4.3 4.3
ISO1600 left as it is: average 2.7 5.2

The comparison shows that the best S/N ratio should be obtained at high ISO settings (800-1600); lower ISO settings supply more green background.
For the D60 I found a more equal noise level at different ISO settings.
The ISO3200 setting should not be used, too noisy and too little dynamic.

clic for animation (209 kB)

Dark frame comparison at 0 degree C in jpg-fine

The performance of the camera at lower temperature increases significantly:
A test series 300sec at ISO1600 shows 2.5-3
The animation shows the noise buid-up at consecutive shooting and a 10x averaged image
Save and view the animation at 200% size for better details.
Noise stays quite low during the shooting, averaging at these conditions does not reduce the noise significantly, see the Veil raw at 0C for comparison.

clic for animation (206 kB)

In raw mode the best S/N can be reached. Again the dependance of noise on the ambient temperature is very obvious.
On the right side there is a link to a graph of dark noise for 22C and -4C. In contrary to cooled CCD the reduction of noise within this temperature span is 40-50% against 50% reduction for each 6C decrease on typical CCD cameras.
Dark subtraction at temperaures below 0C in raw mode is no more very effective (same as in jpg mode), as only a few hot pixels remain in the raws, the residual noise is more random like.

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Light shots Canon 10D

A wide field single raw exposure of M17 with the 4" refractor at f/5 and the UHC filter
The UHC filter improves the nebula structure a lot, this is valid for most emission nebulae

300 sec at ISO800, WB sunny, temperature +20 degree C

raw frame at 50% size

(314 kB)

raw center at 100% size

(231 kB)

A wide field single raw exposure of NGC6992 with the 4" refractor at f/5 and the UHC filter

300 sec at ISO1600, WB sunny, temperature 0 degree C - noise decreased significantly

raw frame at 50% size

(267 kB)

raw crop at 100% size

(120 kB)

An exposure of M57 with the C11 at f/10

120 sec at ISO800, WB sunny, temperature +15 degree C

comparing the 2 images drastically shows the big step from a raw to the final product

single raw at 100% size

(64 kB)

20 x 120 sec processed

(25 kB)

First light for the Canon 300 mm f/2.8 L USM lens aimed at Comet 2P/Encke near M31

ISO800, WB sunny, temperature 0 degree C, lens fully open

The very high quality of the lens provides round stars even at the corners with moderate chromatic aberration

single 60 sec raw at 100% size

(424 kB)

3 x 180 sec processed at 50%

(266 kB)

Again a raw-final comparison on a crop of M42/43 with the 4" TMB refractor at f/5

Data for the raw file: unfiltered, ISO400, WB sunny, temperature -4 degree C

Both crops are 100% size, the raw is a 300 sec exposure without any touching just out of the camera;
The processed image contains 26x5 min, 8x60 sec and 2x10 sec exposures at ISO200 - ISO400

single 300 sec raw crop

(56 kB)

processed image

(65 kB)


Pro's for the 10D:

* Big chip: 23 x 15 mm
* High resolution: 3072 x 2048 active pixel
* Remote interval timer (option) enables automated sequences of long exposures
* Improved Canon remote capture software allows interval exposure sequences up to 30 sec
* One shot full color saves exposure time and makes image aquisition simplier
* Widely useable with all Canon compatible lenses during night and daytime
* Very Reasonable price compared to Astro-CCDs

Con's for the 10D:

* No focus mode (painful !)
* No subframe readout possible
* max 12 bit raws instead of 16 bit for most astronomical CCDs
* No cooling possible: better operation (S/N) during cold ambients.
* Practical exposure time is limited to 10-30 minutes depending on ambient temperature.
* Low response for H-alpha (1.2% absolute!), very fast lenses needed to get a signal, see spectral sensitivity charts: here (French)
* Maximum usable sensitivity: 1600 ASA, compared to 5000-10000 ASA for monochrome CCD like ST10XME or the STL11000M.

These limitations are critical when imaging dim objects, for H-alpha imaging and for high resolution imaging with long focal lenghts (slower f/factor).

Amateurs that prefer best sensitivity still have to stay with a monchrome cooled CCD with high quantum efficiency and they have to pay the higher price for it. From the economical and fun viewpoint the Canon 10D provides reasonable deep sky capability and serves as an almost perfect camera body for 24 hours a day!

To get decent deep sky results with the 10D you need good skill of image processing, working with darks, flats, DDP, deconvolution to get the best possible results out of the raws of this state of the art consumer product.

Information and literature helpful for digicam astro-imaging

Article in Sky & Telescope, June 2004 edition: D-SLRs for Astrophotography

!! FAQ - digicams for astronomical use !!
Al Kelly's guide to Acquiring and Processing
Photoshop for Astrophotographers by Jerry Lodriguss
The new CCD Astronomy by Ron Wodasky
Astronomical Image Processing (book and software!)
ImagesPlus (imaging processing software, video tutorials)
dslrfocus (Focusing software for Canon DSLRs)