Telescope Reviews: DSI CCD Question

Hi, Thomas!

I've been doing deep sky imaging for a couple of years now and have gone from a Meade DSI Color to a Meade DSI Pro (first generation--like you are considering) to a Nikon D50 DSLR to an SBIG ST2000XCM and, most recently, to an SBIG STL-11000M. I have also gone through a progression of optical tubes and mounts. As a result, I think I can give you some insight into what the camera is capable of and what challenges you are likely to encounter.

First, the DSI-Pro is a very sensitive camera (a good thing) with a very low noise Sony chip. There are two downsides: the chip is quite small, so you will not get a very wide field of view, especially with your 8" SCT, and the monochrome cameras are relatively difficult to use. As a beginner, expect to spend two hours on the computer processing and fixing your photos for every hour you spend capturing them. That ratio is more like 1:1 if you are using a color camera (at least until you start to get really picky about your images, at which point it goes back to 2:1).

My biggest concern with the route you are taking is not the camera, but the telescope itself. An 8" SCT has a relatively long focal length, which makes it much more unforgiving of slight errors in polar alignment and tracking than, for example, a small refractor. I would definitely recommend an f/3.3 focal reducer if you get the DSI. That way you will be imaging at more like 600mm focal length--much easier to do. You will need to use the wedge, by the way, or field rotation will cause your stars to arc in as little as fifteen or twenty seconds.

One other choice I would seriously consider is a digital SLR rather than the Meade DSI. The camera wouldn't be quite as sensitive, but you get a much larger chip for approximately the same money (especially if you look at the used market). I would recommend a Canon DSLR simply because the user base of astrophotographers with Canon cameras is, I believe, larger than all the other brands combined. If you can afford something with Live Preview (or whatever Canon calls it) that will make focusing much easier. The DSLR will give you a much wider field of view with essentially the same spatial resolution. The major downside vs. the Meade DSI is a loss of red sensitivity in the DSLR. Plus, you won't be able to do emission line imaging with the DSLR. Obviously, neither camera is cooled so you will be limited in your exposure duration, but without autoguiding that is not likely to be a concern.

As has already been recommended, spend some time on the Beginning Imaging forum as there are lots of people who have been through what you are now going through.

If you want to look at a typical progression of images over time, you can see my gallery here. In particular, look at the Crab Nebula image (taken with a DSI Pro when I was just starting out), the older M51/Whirlpool (taken with an SBIG ST200XCM), and my newest M51. That will give you an idea of how your skills might progress. Like you, I have kids, so it has taken me two years to get to this point. I only manage to get out about once a month. You might do better if you can find more time.

Best of luck with your endeavors!

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- Jared Willson

Fluorostar FLT-110 w/ TEC optics
Vixen VC200L
Astro-Physics Mach1 GTO
Stellarvue SV80S
Takahashi Teegul SP Mount
STL-11000