New Equipment Configuration Learning Experience

Even small changes in an equipment configuration, can create the opportunity for learning...

SH2-132 Lion Nebula with ZWO ASI2400MC & Big Bertha

This image is the product of three night’s imaging from the front patio (29-31 August 2023 – YES in the midst of August’s full Blue Moon).  This is the first time I’ve used my ZWO ASI2400MC camera on the RC-8” telescope. So, it provided me the opportunity  for three lessons learned over the three nights of imaging.  

sh2-132 lion nebula

Three lessons and a wonderment...

First lesson – I’ve successful imaged (and focused) with Big Bertha and my Canon EOS Ra for the last two years.  I learned on the first night, replacing the Canon EOS Ra with the ZWO ASI2400MC, I need another extension tube.  There isn’t enough backspacing with the RC’s 4” of extension tube to achieve focus.  Not to be defeated – I ended up pulling the attachment tube (that attaches to the camera and slips into the telescope throat) out by about ¾ of an inch and was able to focus. It felt a bit precarious and when I had to rotate the camera to frame the target, I had to redo the focus because there’s nothing holding in its “pulled out from the stops” position! I spent some time searching for another extension tube piece, starting with Orion.  They don’t have any in stock (due to supply chain issues) but had me send an email with the request, so they can see if their warehouse can cannibalize extension tubes from a telescope there!

Second lesson – Although I need the field flattener for the RC-8” and my Canon EOS Ra full frame, I do NOT need it with the ZWO! I imaged the first half of the first night with the FF and the coma on the stars was horrible! I took the FF off when I did the meridian flip (yes, and had to redo the focus!) and didn’t use it on the subsequent nights.

Third lesson – When the car battery you’re using for power to the mount and camera fails – it gives you no warning, NONE!  On the second night of imaging (30 August), everything was going well until I went out to do the meridian flip.  I came out to the patio to find the telescope in the pre-flip position (as if it was still imaging), but when I opened the laptop, I found that all the software had shut down.  I parked the telescope and attempted to do the meridian flip.  The EQ6-R mount was acting weird.  First, as it was taking the plate solve images the first one would be fine, but the second one would be filled with star trails, that it couldn’t resolve. I tried three separate times – no joy. The last time, the mount was acting especially weird – stopping and starting, and moving really slow – and again with the star trails, then everything locked up.  At that point, I noticed the DC splitter I had the mount and camera plugged into was flashing – as was the light on the mount. I looked down at the LED display on the splitter – the battery was at 10.5 volts! Hmmm, no wonder it was acting weird…you try to heft around and precisely point a 20 pound telescope when your battery is drained!!  I figured I’d go in and get the gel battery that Paul’s been setting up for the Chile trip and use that – he hasn’t completed the wiring (I won’t go into the why of his wanting to make it extra secure – so that ended imaging for that night.  The next morning we got a new battery, charged it up, and I imaged that night, for the third session in this image.  There were some clouds in the area so I lost about 2 hours throughout the night when the autoguider lost its star and terminated the sequence. But I still got the best data (57x5minute) subframes of all three nights.

…and a “wonderment” – Why is the ZWO ASI2400 seemingly disregarding my gain settings?  Frequently, I forget to check the gain before I start a sequence and end up with the gain that SGP decides upon.  On 31 August, I was very intentional about setting the gain=300 (high) before each time I started a sequence.  All to no avail, as all the resulting images were captured with gain=158 (medium)! The camera control panel in SGP was showing the right number, but the number line green bar seemed stuck on 158 regardless of the setting I input. I communicated with Nico Carver ( about this issue and he told me: “One of the frustrating things about SGP is there are many places to do the same thing, and so it can be hard to troubleshoot. The upside to that complexity is it makes the program more flexible, which is part of why I still use it. My guess is the gain setting you are picking is getting overridden by either the equipment profile or the sequence profile at some point. Check the gain under: Tools->Equipment Profile Manager and under Control Panel->Camera and also under the Event settings within the sequencer. Hope you can figure it out!” I didn’t and haven’t yet – so that will be a lesson to learn for another time!