New Camera – USB issues – Sweetman Astrophotography

The weather has been horrible for imaging for the last two months, so this site has been dormant. Last week I saw a good deal on a used astrophotography dedicated camera, made the purchase and it arrived coincidentally with a new moon and some clear skies, so I got to give it a run out on the first night. This comes close to completing one configuration of my rig, so now is probably a good time to run through the set up I have and discuss what more I’ll try to add to it.

This rig consists of:

Mounts: Celestron AVX

Telescope: Apertura FPL-53 with Field Flattener and guide scope

Main Camera: ZWO ASI 294mc pro

Guide Camera: ZWO ASI 120mm mini

Filter: ZWO filter drawer and 2″ L-eNance filter

Dew Heaters

Control software: N.I.N.A., PHD2, CPWI

Wishlist: AutoFocuser

One thing I’ve learned is that you need to keep your expectations low, new equipment is often complex and takes more than one night to set up and tune to the point where it’s working well enough to image. This night was no different. After setting up, adjusting the back focus and then taking some short test shots for focus adjustment, things fell apart. Guiding failed and the camera no longer downloaded images, tried the usual disconnect-reconnect, etc., but nothing seemed to get guiding working consistently or the camera downloading. I packed it in when a rather large bear came wondering by.

That at least gave me a starting point to search for answers. I found message board posts indicating similar struggles, which seemed to be related to the USB connection. That at least indicated part of the common error with the guiding, I was running several USB connections through a single USB hub. I first tried running the guide camera and the main camera directly to the controller PC directly, and it still didn’t work. I have a pretty ancient laptop, and not all the USB Ports were the same speed. I found that if I ran the main camera to the fastest port, then the guide camera could go either independently or through the USB hub, and the setup seemed reasonably stable.

Then it was time to start a test imaging sequence. I went with a 5 minute subs(sample below), and was quite pleased with the results. I’ll discuss the stacking and post processing in the next post.