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.
The biggest challenge with deep sky astrophotography I have is light pollution. Where I live, and depending on the night (Friday night football games are very common in my area) the light pollution limits my sub exposures to less than two minutes. Anything exposed over 90 seconds is even questionable with the amount of sky glow that can saturate my image sensor. Because of this, I can benefit from the use of a light pollution filter.
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.
I’m working through some equipment tests before I use my ZWO ASI174MM for Deep Sky Imaging. Using RGB and a UHC filter, this camera can do well. The video above shows some of the simple