Mon, 05/18/2015 - 01:25
Would like to give this mode a try! I plan to use it with an 8" f/3.7 scope on equatorial mount, so probably up to 60s exposures unguided. Have been checking a few cameras, and would like to get some recommendations. I read the unmodified Canon's are probably the best. The 40D, 50D, 450D, 1100D all seem to be in my price range.
Which of these cameras have the best software and would work best remotely via USB control from my PC?
Which are lightest weight?
Which have mirror lockup, or is that really necessary to control vibrations? (My mount is fairly lightweight GP-DX).
Which have the easiest, trouble-free interface to "free" photometry software for their RAW formats?
Or any other camera suggestions? Thank you!
Mike
Hi,
Assuming 10 microns the size of the pixel on the sensor, then that corresponds to an angle of about 2.7 arcseconds for your 200*3.7 = 740mm focal length. Those 2.7 arcseconds will be drifted during 0.2 seconds of Earth rotation.
You will need to track, so consider a good mount.
Alex.
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or a lighter, and shorter (focal length) scope.
I'm just a beginner, but following the course of Mark Blackford on variables DSLR, Now, I'm currently testing several setup ...
For now, the best setup I've done is:
Canon 450D unchanged with 300mm.
EQ-3 with synscan goto (it's old but I can make 40-50 sec without guiding)
MaximDL to take picture (to standard "fit" easier to Treaty)
AIP4WIN for treatment.
For now, it's work well but I want to make many test before start to make report
Soon, I want to test MPO Canopus for photomery...
JBD
[quote=JBD]
For now, the best setup I've done is:
Canon 450D unchanged with 300mm.
[/quote]
The 450D seems a good camera, and very reasonable priced. Its even used as an example in the DSLR manual. A few other questions come to mind:
The specs I see say 30s is max exposure, is that it?
Is this camera fully control-able remotely from the PC?
Can the mirror be locked up manually before exposing? Some thread I found on a forum someone said a "glitch" prevents mirror lockup when you operate by remote software?
Is 0C the lowest operating temperature?
Mike,
After taking the DSLR course, I have been doing photometry on bright stars (especially Nova) that are too bright for my CCD set up (16 inch scope). I am using a 50D. Most of what I have been doing is a 50D, 85 mm, f/1.8 lens with 30 sec exposures on an iOptron Smartseries Cube mount. It is a little portable mount that can run in EQ or Alt/Az mode. I am tracking even though at 30 secs I can probably not track. With this mount I have the ability to lock up the mirror but have not had a need to. I have run it a few times from computer with the EOS utility and Maxim. A 30 sec image with this setup can comfortably get down to 9th mag in 30 secs. I have also intended to use it at prime focous on my 80 mm f/6.25 refractor that is piggybacked on my Meade 16 on an AP1200 mount but just haven't gotten around to it yet. It's just easy to take the little iOprton mount out, plop it down and take a few images then I am done.
I know you said that you are planning on using it with an 8" f/3.7 but you may want to consider a camera lens and just piggybacking it to use the mount for pointing and tracking. You will get a wider field of view and more comp stars with a camera + lens setup and if you need to go deeper than 9th mag then go with longer exposures.
Anyway, I am very happy with the 14 bit Canon 50D for photometry.
Barbara
Hi Mike,
I've used a number of Canon cameras, including the 450D and 1100D, and all have been fine for photometry if a few basic setup steps are taken. I've never used mirror lockup since my focal lengths have always been quite short (480mm and less) and the camera is securly attached to a sturdy mount.
Someone in the last DSLR Photometry course mentioned that the 1100D did not have mirror lockup but a quick google search indicates the 450D does. Both cameras are quite light, the 1100D possibly a little heavier than the 450D.
I'd opt for the more recent model. The 450D is quite old (released in 2008) compared with the 1100D (2011).
Focus should not be sharp, you need to spread each star image over lots of pixels (FWHM >8 pixels).
For computer control of the camera function I've used EOS Utility (comes with Canon cameras) but it is quite basic. I haven't had much success focussing camera lenses via EOS Utility.
BackyardEOS is not free but isn't expensive, has lots of features. Canon electronic lenses can be focussed remotely with BackyardEOS.
The RAW images produced by different Canon DSLR models are not the same. AIP4Win is a very good program for processing DSLR photometry images. Not free but comes with a very fine book on astronomical image processing.However 1100D RAW images cannot be opened directly in AIP4Win, they need to be converted to DNG format with a free program from Adobe.
IRIS is free but has a number of limitations and I don't recommend using it.
Another free program for Canon RAW images is Munwin which has some nice features, a logical work flow and good documentation. I'm leaning toward using Muniwin in future DSLR Photometry courses instead of IRIS.
I hope this helps. Cheers,
Mark
Hi Michael
I pretty much agree with what Mark and Barbara have said.
I took Mark's great course and now do both visual estimates and DSLR photometry. Both suit my budget and time constraints.
I bought a second hand Canon 1100D (half the retail price) and a (new) Canon EF 100mm USM lens. So for less than $1000 I was able to get started.
I use a tripod for short exposures and piggy-backing on an alt-az LX-90 for longer exposures. As Mark said, you need to defocus. Combined with a wide field, this works well.
I do use the free Canon EOS Utility and am able to (de)focus my particular lens with this. It has a basic image sequence automation feature so is OK to start with. I use IRIS for processing and photometry. I run both on my Mac, with IRIS under WINE. I agree with Mark that IRIS has limitations and I'm also looking at alternatives such as Muniwin (and others). Having said that, I have been reasonably happy with it. I have also written a Python script that allows me to automate some FITS header updates at various points during the processing but that's not essential. Happy to share that.
I do like to use free software where possible, probably unsurprising since I develop VStar.
Many of us use Excel spreadsheets that came out of Citizen Sky and are in the process of being improved by people like Mark.
I agree with others that wide field DSLR photometry is a good option and I have found it to be a nice transition from binocular visual estimates.
The community of DSLR photometrists is slowly growing and with it, the experience base, so keep asking questions, and we'll tell you what we don't know yet.
David (BDJB)
Thanks to everyone for their very helpful comments! I decided to get a used 450D, could find a refurbished one "sin lente", but with all accessories for well under $200 on ebay. Even if it's not the best most modern one, I have little to lose at this price :)
After I play around with it, I'll get back to this thread if any issues come up.
Mike