When acquiring any exposure, regardless of the duration of the exposure, the sensor will generate some noise. Some of that noise is electronic randomness which can be eliminated by subtracting bias frames. Some noise is actually signal generated by the chip. Dark frames are used to remove this unwanted signal. I immediately noticed how much of this thermal signal was present when I first started my deep sky experiments with the ASI174MM. I'd like to say that this is my original idea, but I actually saw people doing this hack with DSLR and other cameras. It was clear that I would be able to quickly and inexpensively come up with my own cooled ASI174MM camera hack.
One of the most demanding challenges any astrophotographer will face with every project is generating a sufficiently high Signal to Noise ratio (SNR). There are several kinds of noise in every sub-exposure and a detailed description of each kind of noise goes beyond this posting. My focus here is the method I used to quantify the ASI174MM sensor noise as it relates to long exposures. The simplest way to do this test is to accumulate a series of dark frames in a controlled setting.
Before I can get into DSO imaging with my ASI174MM and FireCapture I first need to learn how to use FireCapture! In my previous post in this series I explained my placement of the light pollution filter in line with the RGB filter wheel. So far this looks like it will be the most promising arrangement when attempting to use my ASI174MM for DSO imaging.
Ever since I got into doing astrophotography, I've been imaging with a DSLR. My very first attempts were with a Nikon D7000, and then I quickly switched to a Canon T3i. I was comfortable with it, largely because of Backyard EOS. Now, as I have grown in my skills, I'm ready for a new camera with specialized features. I'm ready for the ZWO ASI174MM Monochrome Planetary Imaging Camera. I'm ready to kick some ass!
For this review, I'm going to spend my time writing about my decision to buy the Canon T3i, how it performs as an astrophotography camera, as well as some other things I've used it for. I won't go into any of the technical specifications because there are probably a million websites out there that have the exact same information. Besides, I'm pretty sure that if you're reading this, you either don't care about the technical details, or you already know them. Either way, covering them would be a waste of your time.