Using the ZWO ASI174MM And FireCapture for deep sky imaging
I know it’s been a long time since I last posted an update. Some of you may have even forgotten that I was even here! I assure you, I’ve been around, and busy. I’ve been writing 5 posts about using the ZWO ASI174MM And FireCapture together. This one was the first to be completed. The others are nearly done – and I should be able to have them out over the coming weeks, as I don’t want to spam your inbox. If you follow my Facebook page, you’ve seen me working on various things, but I want to get back to my deep sky imaging experiments, and today I am discussing my efforts so far with the ZWO ASI174MM And FireCapture.
Before I can get into DSO imaging with my ZWO 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 ZWO ASI174MM for DSO imaging. In my home office, I was able to do quite a few tests of this setup with or without clear, starry skies. All I was really concerned with was my ability to acquire some data in the form of Flat, Bias, and Dark frames. However, before I could even collect these test frames, I had to learn how to use my ASI174MM and FireCapture well enough to do so!
Patience, practice, perfection
A lesson I learned the first few nights out with this camera was that I was a clunky users in the beginning. Transitions between filters, and the filter settings in FireCapture were sloppy, unpracticed, and generally unpleasant. Before I hauled my gear out under the stars, I wanted to make sure that I know what the hell I’m doing so I did not waste hours of my time, and in turn, miss out on dozens of sub exposures. In short, I don’t want to spend my nights learning how to use the ZWO ASI174MM and FireCapture. I need to practice my techniques with FireCapture controlling my ZWO ASI174MM for taking deep sky object photos. I did the learning in my own home, because getting an actual image is less important than getting the expected behavior that generates the images. I worked for several weeks to learn and devise my own workflow.
When I used my ZWO ASI174MM and FireCapture to do planetary imaging, my exposure times were just a fraction of a second. For imaging deep sky objects with my ZWO ASI174MM, I wanted to be able to expose a frame for a lot longer than one minute. I’d prefer upwards of five to 10 minutes, and the default planetary settings just wouldn’t allow me to go beyond one second. I spent about 30 minutes trying to figure out how to take an exposure longer than 1 second. I couldn’t seem to find much information from the FireCapture website that helped to guide me in the right direction. Ultimately I think that through brute force, I figured it out well enough.
Looking for an easy way to do a time consuming task
The key to being able to fluently use my ZWO ASI174MM with FireCapture was going to be the intelligent creation of profiles. I created a DSO profile, and I think that I’ll be able to toggle it on so that the camera and FireCapture will be ready to image with much less prep time in the field. A second profile for the various frame types could also be created, such as DSO_Dark, DSO_Bias, and DSO_Flat. The main reason for creating the profiles is so that the file data type (FITS) and the root file name can be specified.
With the profiles created, I still needed to work with my image capture software and become more practiced in navigating the interface if I want to seriously use my ZWO ASI174MM and FireCapture for deep sky astrophotography. In conjunction with creating comprehensive profiles for my ZWO ASI174MM and FireCapture, the attempted to learn more advanced techniques. I thought it was critical to learn the ins and outs of using advanced features like dithering with PHD2 and adding delays between exposures.
Missing features that I need
While learning how to do deep sky astrophotography with my ASI174MM camera, there were a few features that could not be easily found and may very well not even be a part of the package. Among those features is dithering sub exposures with PHD2. There is considerable noise accumulation in the ZWO ASI174MM and FireCapture needed to be able to help me correct for that. Dithering is necessary to help reduce the effects of the noise and the hot pixels that become apparent in the lengthy exposures. A second feature that I’ve not been able to build into my capture profiles is a delay or pause between exposures. In my experience with DSLR photography, adding a nominal pause of 10 seconds has been beneficial. Over the course of a night in North Texas, the temperature can be (but is not always) reasonably stable. Severe drops in temperature after sun set can happen, but sometimes the drop is more gradual. On these nights, a stable camera temperature can be achieved by allowing the camera sensor to cool down between exposures for a few seconds. FireCapture tends to want to execute exposures with no delay in between. For planetary work, this is very desirable. It allows several short imaging runs to take place in rapid succession with minimal planetary rotation between the sessions.
If I cannot add a delay between my sub exposures, there is no way to allow my ZWO ASI174MM to normalize its’ temperature between exposures – and by extension – I cannot dither manually. I fear that it is actually no longer viable to use my ZWO ASI174MM and FireCapture as a DSO astrophotography platform. Don’t misunderstand this as me saying that FireCapture is not a quality program. The ZWO ASI174MM and FireCapture combination work amazing for planetary photography. It’s only for deep sky photography that I will have to find an alternative.