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Archive 2010 · An Ideal Astronomy DSLR? - Canon at NEAF
  
 
jimmy462
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p.1 #1 · An Ideal Astronomy DSLR? - Canon at NEAF


Hi All,

Thought I'd pass this along...

Canon was in attendance at this years NorthEast Astronomy Forum (aka NEAF...

http://www.rocklandastronomy.com/NEAF/index.html

...) and was asking its booth attendees to fill out a questionnaire for what they would like to see in a new DSLR geared for astronomy. (For those who remember, Canon did offer the 20Da a few years back which offered such niceties as a broader-spectrum CMOS filter and an early version of Live-View focusing.)

Now, I should have just grabbed a copy of the darned thing to post here, but I'll do my best to recall some of what they were looking for...

A question about size preference...Rebel, 50D/7D, 5D2 or 1D.

A question about features...ISO...NR...MP...etc....and then there was this interesting choice...mirror, no mirror...which prompted me to get into a discussion with the two reps about what they meant with that question. This lead to a discussion about whether the camera would have a typical optical viewfinder or whether it would be a Live-View-only camera, and would the camera be a dedicated astrocam or could it be used for normal photography, as well. The one rep mentioned that Canon "already has a transparent mirror" which could find its way into such a camera (which I thought was interesting to hear) and so I enquired whether they were referring to something along the lines of a pellicle mirror...to which they said, yes, they were looking at that and something else that would work the same way. (Hmm, interesting again.)

And, finally (though there were a few other questions that elude me) there was an open question regarding whatever else one would like to see in such a camera. Which led to another discussion about high-ISO capabilities, NR and video frame rates since the reps saw my responses for ISOs of 200,000, 400,000 and 800,000...improved NR and DR...and full-HD rates of 120, and 240 fps. As I explained to their questions...well, now that we have ISO 102,000, can we clean that up to perform like ISO 1600 does today...and since you're asking for a wish-list, why not double that and more, there are lots of applications for this with live viewing of aurora, and many other telescopic faint-fuzzies!...that it was "clean" who would want for an expensive, cooled CCD cam and all the gear one needs to hook up with that just to get some images...and for high-speed shutters there are lots of events from occultations to hummingbirds in-flight for which one could use real full-HD slo-mo. I told them that when they make a camera that I can use for existing-light photography of owls at 2 a.m. in the morning, I'll buy it! We all chuckled.

Which brings me to the point of my post...

I am curious, since Canon is asking, just what is it that you would like to see in a camera specifically designed for astrophotography, and, in a broader sense (or, narrower, depending how you look at it!), extreme low-light conditions?!

Great light,
Jimmy G



Apr 23, 2010 at 04:17 PM
BrianO
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p.1 #2 · An Ideal Astronomy DSLR? - Canon at NEAF


I'd like to see some kind of electronic cooling system to keep the sensor from heating up during long exposures. That would help reduce noise.


Apr 23, 2010 at 05:51 PM
ngc7789
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p.1 #3 · An Ideal Astronomy DSLR? - Canon at NEAF


Real bining would be nice to trade resolution for sensitivity.


Apr 23, 2010 at 07:05 PM
Andrew Welsh
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p.1 #4 · An Ideal Astronomy DSLR? - Canon at NEAF


The smaller pixels actually don't help much. Just means more magnification to reach nyquist sampling limit... and in most cases, 10" scopes or smaller the pixels are smaller than seeing or the scope allows.

A camera body that can handle dew/frost and wider temp ranges without flaking out. Mine hasn't flaked yet, but it does get dodgy around 10 deg F or less.

I like the 40D and live view personally.. although the XSi's (or XTi?) and later with live view do the same job as well. Lighter is better. Video mode is a must.

Debatable whether you'd want a clear glass cover on the sensor or a UV/IR blocker. The common astro-application would require a UV/IR blocker, but something could be said for using an IR pass filter and shooting planetary videos. I've used my 5D Mark II to shoot planetary, and it didn't do that bad. My only challenge was getting enough magnification (w/a 2x TC and 1.4x TC on an 8" SCT the magnification wasn't enough)

+1 for binning, esp. w/12+ MP cameras.

My tests show that stacking the additional ISO 3200+ shots you'd get in the same timeframe over ISO1600 doesn't reduce noise. It does reduce dynamic range though. And it really ends up being about total integration time anyway. You could shoot ISO400 and stretch it.. of course the practicalities of how well your mount tracks and airplane/meteor streaks etc. factor into what constitutes an "ideal exposure time".



Apr 23, 2010 at 07:18 PM
Mike V
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p.1 #5 · An Ideal Astronomy DSLR? - Canon at NEAF


Wow, some of the things have huge potential for video.

Maybe Canon is producing a camera that is more suited to video as well as an astronomy edition?






Apr 23, 2010 at 10:09 PM
ragebot
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p.1 #6 · An Ideal Astronomy DSLR? - Canon at NEAF


I have a 1d4 and consider it the best camera Canon has ever made, but don't consider it the best digital astronomy camera I have. First off most astronomy sites divide astronomy photography into at least three different types.

I have a SO <.3A HA filter and a Baader 90mm ERF mounted on a 120mm achromatic OTA, which is basically a setup to view the Sun with. The ERF is an Energy Rejection Filter that reduces the light intensity by well over 95%. The Solar Optics filter only lets in Hydrogen Alpha wave length light with a sub .3 Angrstrom band width, which basically means an APO does not buy a lot because of the narrow red bandwidth means no CA. I also have a Lunt 60 CaK OTA, and a DS SM40 filter setup mounted on an ED80.

But enough of the nerd talk, capturing solar images means very fast shutter speeds and low ISO settings and noise is not really a problem. Seeing (a measure of how bad stuff like air currents, thermal cells, and clouds and dust in the air) normally limit magnification to fairly low levels. Bottom line for this type of imaging is a 3-4 MP camera can capture all the detail the stuff in front of it provides. As with almost all astronomy photography you are attaching your camera to a hole in the back of the telescope that ranges from 1.25 in to 2.25 inches across so a physically small camera is a plus. I have two of the older Nikon Rubic Cube bodies (CoolPix 995 and CoolPix 4500) and these are the cameras that consistently produce the best images for me. Runner up would be the 7d with live view being a big plus, but its size and weight being a down side.

Next up is moon photography. Even with a huge slow OTA (Optical Tube Assembly, something lots of peeps call a telescope) like the the pier mounted scopes in a shuttered dome you still have what most of us would consider fast shutter speeds, especially considering you often have a support system (tripod) that costs more than the OTA did. I often shoot 1/125 or 1/250 even with filters and ISO 100 or 200. A small light DSLR like the my xti works well for this type of shooting, and the minimal mirror slap on Rebels is a big plus. But I just have a 350 so I often choose the 7d for its live view.

Moving along planets and their moons are next. But shooting a big bright (relatively speaking) planet like Venus is different than something like Pluto (don't get me started about it being or not being a planet) which is always going look like a star than a planet. While the only thing you can photograph is the cloud cover on Venus (but you can use filters to get more detail) planets like Mars, Jupiter, and Saturn do have detail that can be captured, especially with wise filter choice. Shutter speeds vary a lot, but most peeps are using video and stacking lots of images at the start of the post processing, and the work flow can get long and complicated. You really don't see super long shutter speeds or super high ISO settings for capturing images of planets closer than Saturn. I have had good results with the Nikon Rubic Cube bodies and small light DSLRs. But quite frankly the key to this type of photography is the mount the OTA is on. Many peeps are stacking thousands of video images shot over minutes of time. There are software programs designed to select the best video frames for stacking so this is not as hard as it seems.

Last is capturing images of what most peeps call DSOs (Deep Space Objects). Some like Orion's Nebula can be seen with the naked eye and normally need shutter speeds of 10-30 seconds with ISOs of 800 or less; but filters can add to exposure time. While M42 (Messier object 42, the Orion Nebula) is a bright DSO many require exposure times measured in minutes or hours, and quite frankly specialized cameras are much better than a DSLR for this type of photography.

So what is my dream Canon DSLR for astrophotography. Well it needs to have a small, light footprint. Hanging a big heavy body like a 1d4 off the end of an eye piece holder at the end of a diagonal at the end of focusing tube puts lots of stress on the tubes that make up the light path, requires stops on the focuser to keep it from moving, and requires more counter weight to keep the OTA in balance. Because seeing and other factors limit the detail you don't really need lots of MP, I would say 4-6 MP would be more than enough. Probably 2 MP would be enough. I would like to see binning however because that really cuts down on the exposure time. True hardware binning is not that easy (or good) for Bayer sensors like Canon (and almost everyone else uses); so I would like to see a Foveon or BW sensor in the camera. Keep in mind that lots of astrophotography is done using filters of some flavor, and they are often narrow band filters so BW is not that much of a problem. It is also common to take a RGBL image using a Red, Green, Blue, Luma filter and then stack all four images if you want color. There are however software programs to put false color in these images based on things like temperature (cloud bands on Saturn are blue at the colder poles and red over the hot equator). Both the Foveon and a BW sensor use similar binning methods, much different than Bayer binning. As you may have noticed I have mentioned filters a lot. My Sigma SD10 has a nice feature, when you remove the lens there is a user removable IR cut filter you can pop out. I have a set of 6 IR pass filters of varying strength I can put in the IR cut filters place for IR imaging. I would like to see Canon do something like this that would allow standard 1.25 or 2in astronomy filters. Both live view and video are a must. I would like HD video with live view out at HD resolution.

For the time being my last request is this camera should be at a price I can afford.



Apr 24, 2010 at 01:58 PM
 

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jimmy462
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p.1 #7 · An Ideal Astronomy DSLR? - Canon at NEAF


Hi Tom (ragebot),

You, of course, bring up quite eloquently the difficulty in designing an ultimate astrophotography camera. The needs of astroimagers are very broad depending upon the application, and I did spend some time discussing these issues with the Canon reps. My take on their interest at NEAF was to get feedback from folks who are currently using their DSLRs for astroimaging as to features they would like to see incorporated in a future model geared more towards their needs.

Sort of along the lines of...Gee, this stinks trying to see the LCD display when the telescope is slewed to this angle, I wish they made this camera with an articulating screen...Gee, those Hutech Ha filters are nice, wouldn't it be great if they gave us a model with interchangeable sensor filters...Gee, it stinks that I can't image the earth shadow on the crescent moon without blowing the sunlit highlights, I wish they would offer a camera with a greater DR...etc.

I don't think they were necessarily looking to break new ground by creating a camera that would suit broader range of applications, but rather to improve the utility of their cameras for how they are currently being used...e.g. deep-sky imaging, planetary videography and nightscape photography...but, I could be wrong on this.

In fact, I could be very wrong on this. I recall stumbling upon a Canon patent a few years back that could address a variety of photographic applications...and not just those dealing with astrophotography. How would a camera with an interchangeable sensor suit you?...

Image sensor - US Patent 6292272 Full Text:
http://www.patentstorm.us/patents/6292272/fulltext.html

...How cool would it be to have a camera where you could swap out a Color sensor card and slide in a Black & White sensor card, instead? Could use low resolution today?...slip out a 24MP sensor card and slip in a 10MP one. As for astrophotography, why not a sensor card for Ha bandwidth, one for solar calcium lines, and one for infrared?

Who knows what the possibilities are here? As I said to the Canon reps, "today's ISO 102,000 is where film ASA 1600 was ten years ago, so why shouldn't I request a clean ISO 102 or 204,000 with a usable ISO 800,000? We're only talking a few more stops here! I'd love to capture the upward flowing currents, that I can see with my naked eye, rising up through an aurora's curtains...in real-time HD!" (That one got a chuckle!) And they said, "Put it down!"

Just some food for thought! Thanks for that great reply!


Jimmy G



Apr 25, 2010 at 02:30 AM
dwweiche
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p.1 #8 · An Ideal Astronomy DSLR? - Canon at NEAF


I'd love to see someone post an example here of what can be accomplished by stacking HD video frames from a DSLR.


Apr 25, 2010 at 04:00 AM
Andrew Welsh
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p.1 #9 · An Ideal Astronomy DSLR? - Canon at NEAF


dwweiche wrote:
I'd love to see someone post an example here of what can be accomplished by stacking HD video frames from a DSLR.

I have used the 5DII to shoot HD video- I shot the ISS and Jupiter- like I mentioned above, the main barrier is achieving a good image scale. Even with a 1.4x and 2x teleconverter stacked, it wasn't enough to get the most out of the camera for my f/10, 200mm aperture (8 in) scope. I can't easily hook up a barlow lens to the camera body (without doofy adapters, flexure + trying to keep focus fixed, etc etc)



Apr 26, 2010 at 03:17 PM
ragebot
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p.1 #10 · An Ideal Astronomy DSLR? - Canon at NEAF


Andrew Welsh wrote:
I have used the 5DII to shoot HD video- I shot the ISS and Jupiter- like I mentioned above, the main barrier is achieving a good image scale. Even with a 1.4x and 2x teleconverter stacked, it wasn't enough to get the most out of the camera for my f/10, 200mm aperture (8 in) scope. I can't easily hook up a barlow lens to the camera body (without doofy adapters, flexure + trying to keep focus fixed, etc etc)


This is why I mentioned a small footprint for the ideal camera. While the IQ and hi ISO performance of my Rubic Cube Nikons is no where close to that of my xti they still consistently produce better results for me, mostly because they are so easy to use. The 4X zoom is also a big OK.



Apr 26, 2010 at 03:30 PM
ragebot
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p.1 #11 · An Ideal Astronomy DSLR? - Canon at NEAF


dwweiche wrote:
I'd love to see someone post an example here of what can be accomplished by stacking HD video frames from a DSLR.


Don't know anyone posting a lot of that type of image; but this guy is my choice for the guru on dslr astrophotography

http://www.pbase.com/samirkharusi



Apr 26, 2010 at 03:36 PM
ragebot
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p.1 #12 · An Ideal Astronomy DSLR? - Canon at NEAF


jimmy462 wrote:
Hi Tom (ragebot),

You, of course, bring up quite eloquently the difficulty in designing an ultimate astrophotography camera.

SNIP .Gee, this stinks trying to see the LCD display when the telescope is slewed to this angle, I wish they made this camera with an articulating screen...Gee, those Hutech Ha filters are nice, wouldn't it be great if they gave us a model with interchangeable sensor filters...Gee, it stinks that I can't image the earth shadow on the crescent moon without blowing the sunlit highlights, I wish they would offer a camera with a greater DR...etc.

SNIP

Just some food for thought! Thanks for
...Show more

Hi Jimmy,

While I like the articulating LCD on my Rubic Cube Nikons even with those bodies I use the live view out to a monitor for a bigger image for my old tired eyes to focus on. I normally image on a c14 mounted on a pier inside a shuttered dome with plenty of table space and electric outlets. Since I already have lots of narrow band filters (mostly 1.25 but some 2in as well) I really like the idea of no IR/UV cut filter on the camera, and think Sigma is way ahead of the game with their design on the SD10. Unfortunately the Sigma SD14 was a step in the wrong direction for this feature. I am also of mixed minds about micro lens and Bayer sensors for astrophotography cameras. True hardware binning is such a big plus that I am willing to give up the great RD already done on Bayer sensors for the advantages of binning. I am also of mixed minds about the DR issue. It is nice to have great DR, but for something like M42 it is very common to expose for the bright center and make a second exposure for the dimmer edges. Not to mention it is common to expose with narrow band filters as well and then stack the two luma and various narrow band filter images to create a final image. So while I like great DR in my day to day shooting for my astrophotography shooting style it is not that big a deal.

Which brings up another point, which is the shooting style of the astrophotographer. I do understand the upside of an articulating LCD, but for me it is sorta yawn and move on feature. On the other hand I also understand for some one with a smaller collection of narrow band filters a band sensitive sensor might be attractive. Since I have access to a pier mounted OTA in a dome, or my Atlas mount for solar observing tracking is not a real problem. But for someone with a less capable support system 100k ISO capability is more important.

And finally my last comment is that the camera should be something I can afford. I look at some of the research level SBIG stuff and think WOW, I would like that. But at prices higher than the new Canon 800/5.6 they just don't seem cost effective.

YMMV



Apr 26, 2010 at 03:54 PM





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