Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 03/20/2020 - 14:41
Has anyone used a peltier cooler for DSLR photometry? I've seen on sale and some videos on making one for a DIY project. Has your experience been positive or negative and would you recommend it over a dedicated astronomy camera?
Tim,
No-one has posted a reply to your question after a week. Although I have not used a cooled DSLR and cannot answer your question directly, I have done a lot of DSLR photometry over several years, and now have used a 12 bit dedicated cooled CMOS astronomical camera (CMOS astro) for nearly a year. Even with a cooled DSLR the following comparison would be relevant. Almost all of it is, I suspect, general knowledge or could be found without too much difficulty. Please just ignore if obvious.
A DSLR may limit the user to one shot colour, whereas CMOS astro allows a choice of OSC or mono. However CentralDS in South Korea http://www.centralds.net/cam/ according to their web site will modify OSC DSLR to cooled mono.
Each make of DSLR has its proprietary RAW format. CMOS astro saves high resolution files as FITS. The latter, of course, particularly with software that picks up astrometry from the field of view, records a large amount of relevant information in the FITS header, more than is possible with DSLR RAW.
DSLR RAW for photometry requires software that handles the proprietary formats, whereas FITS is generic for photometry software. I used to use AIP4Win for my DSLR preprocessing and photometry, and that software operated directly on the DSLR RAW files. They did not have to be converted to FITS, and everything worked very well and pretty fast. However, a while back a lost or corrupted file on my Windows 10 computer prevented opening AIP4Win. I had the file re-instated (at a cost) but the file became lost/corrupted again. I gave up. My current processing for DSLR photometry, which I still do from time to time, is to use IRIS for preprocessing and channel separation, and AstroimageJ for aperture photometry. This is not entirely convenient, although I realize there may be alternative strategies. In contrast AIJ handles the entire processing of my CMOS astro FITS files.
Peltier-cooled DSLR is not mainstream, whereas the market for CMOS astro is expanding.
Peltier-cooled DSLR will limit the user to 14 bit ADC. The first tranche of CMOS astro were 12 bit cameras, but already there are CMOS astro cameras on the market with greater bit depth. At the moment, therefore, anyone in the market for a CMOS astro has a choice which I assume will broaden with time. Someone like me interested in bright star photometry might choose a low bit-depth instrument. I did that and am very happy with the results.
Admittedly I am not overly familiar with Peltier-cooled DSLRs, but looking at the offerings of modified cameras on the CentralDS web site (link in the 2nd paragraph of this post), it seems to me that the cameras are somewhat bulky, with the Peltier cooling module built on to the DSLR body. If a cooled DSLR mono were chosen, the already bulky setup with added filter wheel would be even more so. CMOS astro in contrast are sleek instruments.
Unless someone comes up with a direct answer to your question after finding from experience that a modified cooled DSLR offers other real benefits in practice in comparison with a CMOS astro, my personal choice from the above would be to go with the latter.
Roy