DSLR for astrophotography

[pequod]

I would like to buy a 2nd hand Canon Rebel DSLR for astrophotography . I do not wish to modify my Nikon DSLR. I have read that the Canon is a suitable candidate for modifications and obtainable 2nd hand relatively cheaply. How far back in models do I need to go to get something suitable?

[Mick J]

I would say the 450d would be a good place to start. There is a 450d & a 600d for sale in the classifieds.

[endless-sky]

If you already have a Nikon and some lenses for it that you could use to get started in astrophotography, I would consider getting another Nikon.

When I started back astrophotography with a digital camera, in January of this year, I was in the same boat: I already had a D90, which I didn't want to modify, because I wanted to keep using it also for daytime photography. It's also a very old camera, so not worth modifying it, in my opinion. I started using it for a couple of months and was never satisfied with the results: very noisy, no H-alpha or very little being captured. I felt like I was wasting my time out there for hours and not capture any significant data. So I started reasearching what to replace it with. My research wasn't limited just to Nikon, I looked into Canon as well.

At the end, I chose to buy a used Nikon D5300 (the price was very nice and it only had 2000 shots taken, so basically new). From all the graphs I have seen, the dynamic range, noise levels and overall quality, the D5300 was a lot better than the 60D or the 600D or the other Canon choices that popped up in the forums. So I bought it, used it for a couple of sessions stock: the noise was very little, compared to the D90, the colors popped up more, and being "ISO-less", I could shoot at 200 ISO instead of 800 ISO with the D90. After a couple of sessions, I opened it up, removed the stock filter and replaced it with a UV/IR cut filter that I bought in a 2", round variant and I cut it myself to the exact dimensions of the one I removed (I couldn't find any pre-cut filter that suited the dimensions I needed). Opening the camera and removing the stock filter was very easy. Cutting the other filter was the hardest part, for me. If I could go back, I would probably send it to a professional store that would modify it for me.

Anyway, the modification turned out great and the camera is now very sensitive to the H-alpha emission line and I can capture a lot of nebulosity even in a Bortle 5 zone, with 2-3 hours worth of integration time. I plan to go a lot longer once the nights start getting colder and longer, in a couple of months.

Another thing that I read over and over is how Canon is more supported by the many astrophotography softwares (expecially the free ones). This might have been true in the past, for the older Nikon models, but the D5300 works perfectly fine with AstroPhotography Tool, EKOS and N.I.N.A.

Edited July 28, 2020 by endlessky

[pequod]

Thanks for the replies. I can still use the Nikon for astrophotography but will never modify it. It is out of warranty but still fairly new and immaculate, and of course used for terrestrial. I will keep watch for a canon (modified even better) for future use. I have seen U-toob videos of the conversion - a bit scary, but I could handle it. Is it neccessary to add an additional filter to maintain the focus - and what about the IR focus being different. This is where it gets complicated for me. Can you point me to any reports on this?

[endless-sky]

The advantage of doing it with a Canon is that some models actually have two stock filters: one that blocks UV/IR (good) and one that blocks most of the red, including H-alpha (bad). If you remove only the second one, you are good to go and you don't need to add anything else (unless you want to keep autofocus, which doesn't work and is basically useless for astrophotography - you'll have to focus using live-view or your laptop screen, anyway, which is exactly what the sensor sees).

If you remove the stock filter(s) completely, you'll have to add a UV/IR cut filter somewhere in the imaging train (closest to the sensor is better). This is because lenses do not focus all the light spectrum in the same focal plane. UV is on the far blue end of the spectrum, IR is on the far red. Without a filter, these "unfocused" parts of the light will create bloating in your stars and purple/magenta halos - same as if you would use an achromat instead of an apochromat refractor.

So, my advice is: modify the camera, but leave in the UV/IR cut stock filter (if the camera has one) or add one (if it doesn't).

Edited July 30, 2020 by endlessky