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Picking Cameras and Lenses for Astrophotography

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I am new to the astrophotography (AP) part of star-gazing.  I am trying to get into it with a relatively big leap in a few short months.

I have a Canon EOS 80D that is modified for AP.  I am embarking on my AP career by getting into simply aimed, non-tracked, non guided AP with the EOS, a tripod, and BackYardEOS (BYE).  Just trying to get used to the concepts of prolonged (1 minute to 20 or 30 minutes), multiple exposures with "Lights, Darks, Flats, Biases, Calibration, Aligning, Stacking, Post-processing," and whatever other term I may have left out.  I'm presuming that I can play around with all that stuff with EOS images for the few months that my POD is in planning and construction (It's winter here now in South Dakota).

When the POD is built in the Spring, I will install a Celestron 11" RASA with autofocus and guide scope (all sitting in a corner for now) on a permanent pier and be ready with the EOS and BYE to try some tracked and guided AP with the RASA and all that other stuff with those captured images.  Hopefully by then I will have defined  a better idea of what class of objects I want to aim at.  If you asked me now I might say some like deep sky objects, but that may just be influenced by all the great material I see on the web (like here) and may prove to be beyond my ken or ability.


To answer my INTERMEDIATE TERM QUESTION I am trying to understand all the concepts related to field of view (FOV), pixel size, and pixel resolution.  Where to use an EOS-like consumer camera and where to use a more specialized CCD device and how all that relates to FOV and resolution and things like that.  I have attached an Excel spreadsheet that I put together that shows some relatively uninformed attempts to relate camera/scope FOV and appropriateness for observing different objects in the sky.

MY IMMEDIATE QUESTION :  AM I ON THE RIGHT TRACK with my understanding and approach to defining an appropriate dedicated CCD camera post-EOS?  Or at least when/if I need something different than the EOS.

Thanks for any advice, critique, etc.

Field of View Calculations.xlsx

Edited by rodmichael
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With a RASA you are looking at a setup where the camera sits in the light path (or at least in the middle of the opening). It also is optimized for large sensors according to the blurb. As such, it would be a waste to stick a tiny sensor on there, because at F2, the scope is a widefield instrument with a large aperture and your targets will be the larger nebula as opposed to the small galaxies. I don't know about budget, but going for an 8300 upwards in terms of size would be my recommendation. The pixel scale with the 11000 chips is 3"/pixel which for the size is pretty good, but the ~6 micron pixel chips would be a better technical fit. Filter drawer systems work best from my understanding to prevent a filter wheel intruding into the light path, so imaging sessions need to be a bit more hands on than more automated setups, unless there is something fancy I am not aware of for automated filter swapping in these types of configurations.

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Probably the most important single factor in planning an image is knowing the field of view. This is governed by only two parameters, chip size and focal length. The easiest way to work things out is to obtain a software planetarium into which you can plug these parameters and then place a 'vrtual chip' over any target in the planetarium to see how it fits. I use SkyMap Pro but other planetaria can do the same thing. Here's an example in which the Horsehead and Flame nebulae are shown at two focal lengths, 1015mm for our TEC 140 and 530mm for our Tak 106.

Planetarium FOV.JPG

This is a very accurate method. The resulting image from the TEC is an excellent fit with the prediction...



The RASA is a strange beast because if its extreme F ratio and front location of the camera. As a general 'real world' rule in telescope operation 'extremes' and 'easy' don't go together but the RASA is producing pretty good results. At very fast F ratios astro modded DSLRs do good stuff. This might also be a scope well suited to the newer technology cameras like these: https://www.firstlightoptics.com/zwo-cameras/zwo-asi1600mm-cool-usb-3-mono-camera.html

I can imagine the slide drawer approach to filtering a mono camera might be a hassle (with flats, for instance) but I haven't tried it so can't comment.




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Thanks for your thoughts and ideas.  especially thanks to Olly (ollypenrice) re: using planetarium software to figure out camera and telescope combinations and FOV.  I have used Stellarium as suggested and come away believing that I am on the right track with my spreadsheet calculations for FOV.  With Stellarium there is good correlation with predicted FOV from my spreadsheet.

From an FOV perspective, for M42 the camera suggested by Olly (ZWO ASI 1600M) appears to be optimal, although, the EOS 80D is not far behind.  With the QSI 6120, the object may be just a bit large for the FOV available; although, better orientation of the camera would help a lot and could make it the best of the three.

For Barnard 33, the QSI 6120 may be the best imaging solution with the RASA.  The ZWO ASI 1600M is just behind that and the EOS 80D comes up a bit small in the FOV.

For M31, the ZWO may again be best with the EOS 80D just behind.

With a little bit of information now, it almost seems that the best camera option (combination) with the RASA may be either the ZWO or the QSI ( about 3X $$ compared to the ZWO) + the Canon EOS 80D.  The square frame of the ZWO is attractive.

Let me know if you think I'm missing anything.

The visualization tool in the planetarium software suggested by Olly (and probably well known to most of the people on the forum) is great.  It's just gravy that it seems to correlate with the spreadsheet.  Thanks!!


I can imagine the slide drawer approach to filtering a mono camera might be a hassle (with flats, for instance) but I haven't tried it so can't comment.

I'm not sure what you meant by that comment Olly.


 I don't know about budget, but going for an 8300 upwards in terms of size would be my recommendation.

I'm trying to limit my first camera to something less than $5K.  I would rather be much less than $5K, perhaps in the $1K to $3K range.  The guy I'm working with at OPT says he prefers QSI cameras.  He doesn't like QHY and is  a bit qualified in his comments about ZWO.

Any thoughts out there?

M42 With ZWO 1600M +RASA .png

M42 With EOS 80D + RASA.png

M42 With QSI 6120 + RASA.png

Barnard 33 with QSI 6120 + RASA.png

Barnard 33 With ZWO ASI 1600M +RASA.png

Barnard 33 With EOS 80D + RASA.png

M31 With ZWO ASI 1600M + RASA.png

M31 With EOS 80D + RASA.png

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