First Canon EOS 60Da samples (Andromeda, Orion & Pleiades)!

[kdsand]

They look like black clipping was not done or done poorly, but then again I'm not familiar with how astronomy photographs are supposed to look... Might just be the nebulas, but to me it looks hazy.

Dude they're taking pictures of objects so far away it's hard to even comprehend the distance, I'd say they're pretty damn good for a $1400 camera. But then again I'd like to know what kind of telescope they were shooting through...

The kit lens.

 

[BobSanderson]

The photos posted here are amazing and beautiful. Thanks.

 

[mws]

They look like black clipping was not done or done poorly, but then again I'm not familiar with how astronomy photographs are supposed to look... Might just be the nebulas, but to me it looks hazy.

Dude they're taking pictures of objects so far away it's hard to even comprehend the distance, I'd say they're pretty damn good for a $1400 camera. But then again I'd like to know what kind of telescope they were shooting through...

5200mm f/14

http://www.popphoto.com/news/2010/01/canons-enormous-5200mm-f14-dslr-lens

I honestly have no idea, but I wonder what you could do with that lense.

 

[Lee Jay]

But then again I'd like to know what kind of telescope they were shooting through...

From the OP:

"They used a φ115mm ED Astronomical telescope..."

Maybe a Meade or Vixen?

 

[dstppy]

I wonder if back-lighting or sensor cooling would help at all.

I'm wondering why this isn't the 7Da instead.
Surely, we don't need 19AF points and 8fps for astro.
And the weather-sealing on the 7D probably makes the sensor heat-up faster. Or would the metal-body help with passive-cooling?

Seriously . . . they coulda dinged people for $2k if that were the case . . .

My questions is, can we get some SMALLER images to compare?

 

[whwang]

To begin with, back-lit CCDs are way more sensitive (no Bayer filter + higher QE => up to 5 times more sensitive for a given wavelength) but as important is that astronomical CCDs almost always are actively cooled to reduce the dark current. Dark current can easily be the most signicant source of noise for very faint sources that require long exposures. An additional problem is that the dark current fills up the electron well with time, reducing the dynamic range unless the photo-sites are periodically reset by making multiple shorter exposures, but the problem with multiple exposures is that each readout adds noise.

The advantage of the 60Da on the other hand is that you get all three colours simultaneosly, and at 18 Mpix, for a low cost. And you can easily use it with EOS lenses, something that can be a bit involved for astrophotography-dedicated CCDs.

Hi,

I happen to be an astronomical researcher and an astrophotographer who use Canon extensively. Here are a few of my recent photos taken with a modified 5D2:
http://www3.asiaa.sinica.edu.tw/~whwang/gallery/picutres/M42_2010.html
http://www3.asiaa.sinica.edu.tw/~whwang/gallery/picutres/M101.htm
http://www3.asiaa.sinica.edu.tw/~whwang/gallery/picutres/rosette-2011.htm

I would like to add a few words to the topic on DSLR vs cooled astronomical monochrome CCDs.

As epsiloneri pointed out, a big advantage of astro mono CCDs is their high QE. The fact they don't have Bayer filters allow them to adopt the LRGB color combination, in which they spend most of the time on L and only a little time on RGB. The L filter essentially uses the entire throughput range in the optical spectrum. Coupled with the high QE of the sensors, this produces very high S/N and high resolution in a short amount of time. This is proven to be an extremely efficient way of producing high quality color pictures, and DSLR just can't match this. Even if DSLRs have similar QE as mono CCDs, it will still take a Bayer-style DSLR 2x (or even 3x) more exposure time to achieve the same quality. In my opinion, the biggest advantage of mono CCDs is their flexible filter usage, which allows for the very efficient LRGB and other possibilities.

Many people also think cooled CCDs are good because they are cooled and they have low noise. Unfortunately, this is not correct. First, recent DSLRs produced by Canon and Nikon all have LOWER noise comparing to CCDs from Kodak and Sony. Here I am talking about readout noise. DSLRs' readout noise can be as low as 2-3 electrons rms per pixel (for example, 5D2 at ISO 1600 and 3200), but CCDs are still in the range of 7-10 (even > 10) electron per pixel. This is the same for dark current. Recent Canon and Nikon CMOS chips have dark current that's MANY TIMES LOWER than that of Kodak/SONY CCD chips under the same temperature. The low temperature produced by the cooling system in those cooled CCDs help to reduce their dark current from being miserable to better than DSLRs, but not much better. Plus, even when uncooled, recent DSLRs already have dark current that's comparable or even lower than sky photon rates in most astrophoto environments. So dark current is no longer a limiting factor for the performance of DSLRs on astrophoto, as long as one subtract dark carefully, which is not difficult and doesn't take much time.

So, be happy with the Canon DSLRs you have. They are great, maybe not up to the level of the best cooled CCDs, but not far behind too.

 

[kdsand]

To begin with, back-lit CCDs are way more sensitive (no Bayer filter + higher QE => up to 5 times more sensitive for a given wavelength) but as important is that astronomical CCDs almost always are actively cooled to reduce the dark current. Dark current can easily be the most signicant source of noise for very faint sources that require long exposures. An additional problem is that the dark current fills up the electron well with time, reducing the dynamic range unless the photo-sites are periodically reset by making multiple shorter exposures, but the problem with multiple exposures is that each readout adds noise.

The advantage of the 60Da on the other hand is that you get all three colours simultaneosly, and at 18 Mpix, for a low cost. And you can easily use it with EOS lenses, something that can be a bit involved for astrophotography-dedicated CCDs.

Hi,

I happen to be an astronomical researcher and an astrophotographer who use Canon extensively. Here are a few of my recent photos taken with a modified 5D2:
http://www3.asiaa.sinica.edu.tw/~whwang/gallery/picutres/M42_2010.html
http://www3.asiaa.sinica.edu.tw/~whwang/gallery/picutres/M101.htm
http://www3.asiaa.sinica.edu.tw/~whwang/gallery/picutres/rosette-2011.htm

I would like to add a few words to the topic on DSLR vs cooled astronomical monochrome CCDs.

As epsiloneri pointed out, a big advantage of astro mono CCDs is their high QE. The fact they don't have Bayer filters allow them to adopt the LRGB color combination, in which they spend most of the time on L and only a little time on RGB. The L filter essentially uses the entire throughput range in the optical spectrum. Coupled with the high QE of the sensors, this produces very high S/N and high resolution in a short amount of time. This is proven to be an extremely efficient way of producing high quality color pictures, and DSLR just can't match this. Even if DSLRs have similar QE as mono CCDs, it will still take a Bayer-style DSLR 2x (or even 3x) more exposure time to achieve the same quality. In my opinion, the biggest advantage of mono CCDs is their flexible filter usage, which allows for the very efficient LRGB and other possibilities.

Many people also think cooled CCDs are good because they are cooled and they have low noise. Unfortunately, this is not correct. First, recent DSLRs produced by Canon and Nikon all have LOWER noise comparing to CCDs from Kodak and Sony. Here I am talking about readout noise. DSLRs' readout noise can be as low as 2-3 electrons rms per pixel (for example, 5D2 at ISO 1600 and 3200), but CCDs are still in the range of 7-10 (even > 10) electron per pixel. This is the same for dark current. Recent Canon and Nikon CMOS chips have dark current that's MANY TIMES LOWER than that of Kodak/SONY CCD chips under the same temperature. The low temperature produced by the cooling system in those cooled CCDs help to reduce their dark current from being miserable to better than DSLRs, but not much better. Plus, even when uncooled, recent DSLRs already have dark current that's comparable or even lower than sky photon rates in most astrophoto environments. So dark current is no longer a limiting factor for the performance of DSLRs on astrophoto, as long as one subtract dark carefully, which is not difficult and doesn't take much time.

So, be happy with the Canon DSLRs you have. They are great, maybe not up to the level of the best cooled CCDs, but not far behind too.

Wow.

That's a interesting post with some good points.

 

[outsider]

It would have been nice if canon could have taken these same shots with a regular 60D to highlight the difference.

I wonder how much better the 60Da is over a stock 60D, or if this just marketing talk to market to the astronomer niche market?

 

[epsiloneri]

So dark current is no longer a limiting factor for the performance of DSLRs on astrophoto, as long as one subtract dark carefully, which is not difficult and doesn't take much time.

I'm very surprised to read this, but it sounds great! Do you have numbers for what the dark current actually is for modern DSLR sensors, e.g. in terms of electrons/hour?

 

[epsiloneri]

It would have been nice if canon could have taken these same shots with a regular 60D to highlight the difference.

They did that for the Rosette nebula, in case you didn't see it. See OP.

 

[M.A.S. Productions]

To me, the image from the 60D looks better. The image from the 60Da just looks more red.

 

[Heidrun]

Hope that there wil come some pictures of the milky way with a wideangle lens and 60DA. Because if im gonna get this type of camera. I would 999 times out of 1000 use it to get pictures of the milky way or maybe Aurora Boralis

 

[kdsand]

;D

Just a thought ( ouch )

These pictures were actually taken with a Nikon........



No my bad its the other way around.
That is me being sarcastic

 

[whwang]

[I'm very surprised to read this, but it sounds great! Do you have numbers for what the dark current actually is for modern DSLR sensors, e.g. in terms of electrons/hour?

My own measurement on 5D2 is 0.86 electron per second at 20 deg C, and 0.051 electron per sec at 3 deg C. These are ambient temperature, not sensor temperature. The sensor must be much hotter after continuous operation of several 10s of minutes. The full report I wrote is here:
http://www3.asiaa.sinica.edu.tw/~whwang/misc/Canon5D2.pdf
It is oriented for astronomers.

In general, this page of Roger Clark's is an excellent source for sensor performance that amateur astronomers care:
http://www.clarkvision.com/articles/digital.sensor.performance.summary
Unfortunately Roger's page does not contain much information on the dark rates.

 

[lol]

I wonder how much better the 60Da is over a stock 60D, or if this just marketing talk to market to the astronomer niche market?

See following link for an indication of the possible difference, as they show the sensitivities of a 40D before and after modification. Note the increased red sensitivity, particularly around 6563 angstroms, which is where most of the "red glowy stuff" from nebulas sits. Assuming they haven't radically changed their colour filter since the 40D, then a similar gain is possible. Also note it doesn't significantly change the green or blue sensitivities.
http://www.astrosurf.com/buil/50d/test.htm

Hope that there wil come some pictures of the milky way with a wideangle lens and 60DA. Because if im gonna get this type of camera. I would 999 times out of 1000 use it to get pictures of the milky way or maybe Aurora Boralis

The IR filter modification only gets you a benefit in the deep reds. So for broader spectrum objects like galaxies (including the milky way) there isn't much benefit over a standard camera. I'm not familiar with the causes of the Aurora glow, so I'm not sure if the Da would or would not help there. If it did, it would only be from increased red sensitivity.

Note both the above assume Canon only changed the colour filter, and didn't make any other changes which may improve the image output.

 

[epsiloneri]

My own measurement on 5D2 is 0.86 electron per second at 20 deg C, and 0.051 electron per sec at 3 deg C.

Thank you for doing this, very useful and interesting reading. Did you also characterise the variation of the flat field and the static dark current image? I.e., how much noise you would introduce by not correcting for flat field and dark. I've been impressed by how flat the dslr sensor appear compared to CCDs, so I've wondered if Canon actually has some first-order built-in flat fielder.

 

[whwang]

Thank you for doing this, very useful and interesting reading. Did you also characterise the variation of the flat field and the static dark current image? I.e., how much noise you would introduce by not correcting for flat field and dark. I've been impressed by how flat the dslr sensor appear compared to CCDs, so I've wondered if Canon actually has some first-order built-in flat fielder.

For pixel response, modern sensors in the visible light are all very flat to begin with. This is true for both CCD and CMOS. I think, the most important flat field effect is introduced by the optics (vignetting) rather than by the sensors. Personally whenever I do astrophoto, I try to get a good flat field image to correct for the vignetting (and dust shadow).

For the dark part, as I mentioned in the PDF file, it is not possible (at least to my knowledge) to measure the real dark current in Canon CMOS. I can only measure the frame-to-frame variation of dark images, which is dark noise, and use that to infer what the dark current may be. The frame-to-frame variation is very small as long as temperature is stable. This means that a proper dark subtraction can remove thermal effect very cleanly and leaves very little trace of noise in a dark subtracted image.

 

[epsiloneri]

For the vignetting, I assume you would only have to take a "master flat" for the lens/camera combination once and for all, and then keep re-use it (much like is done in DPP and DxO). Dust may move around of course. I was more interested in the pixel-to-pixel variation of the flat field - how flat is very flat? If you haven't measured it - no problem I can do it myself when opportunity presents, I was just curious if you already had the data. Same thing for the dark current static structure - how much is the pixel-to-pixel variation? I understand it's a differential measurement, but one should anyway be able to measure this (otherwise one couldn't calibrate for it).

0.05 electrons/pix/sec is great performance, 1 electron/pix/sec not so much. The dark current seems to be (surprisingly) temperature sensitive in this regime. That means one needs to match the temperature of the sensor fairly accurately for the dark. Alternatively, optimise the dark subtraction by scaling it with the help of a bias frame.

The 5D2 sensor is also famous for some "band" structure in the dark that unfortunately is not stable in between exposures, and so very difficult to properly remove. Have you made any progress in this area? It will be interesting to see if the 60Da improves in this area.