I have many years of successful experience doing deep sky AP. These days I shoot mostly with the Hyperstar and an Atik 460ex on my edge14.
But having shot most of the targets I like, I thought it might be fun to dabble in planetary AP.....the conversion over has been bumpy.
Here's what I've done and where I'm at:
1. Removed the Hyperstar/FW/Atik and dropped-in the secondary.
2. Off the back I built the following train: Starlight crayford > 2.5 barlow > filterwheel > ASI174MM..there are 'rings and things' in-between but the back-focus is correct.
3. Then I moved the primary into rough focus and locked it.
4. Then I drew-back the crayford to 1/2 way, set the micro-touch controller to 1/2 way (30k) and moved the mirco-touch motor off the native focuser and over to the crayford.
6. At this point I'm just trying to to focus so I can perform a collimation.....here’s where I'm stuck.
I'm not used to CMOS imagers and these settings are foreign. The ASCOM driver for the ASI in SkyX gives me the following options:
- RAW: 8 or 16. I assume this is bit-depth so I've been using 16
- Gain: 0-240. I've been keeping it in the middle.
- Offset: 0-240. Again in the middle
- USB Limit: 40-100. I have it on 51
With these settings, I can ONLY get an image of Vega (or other suitable bright star) if the exposure if 4 seconds or greater. Anything less than 4 and no data. Bin 1x1 and 2x2 both require the 4 sec minimum.
This makes it very hard to autofocus as the @focus3 routine controls exposure time to get to the ADU it decides is best BEFORE moving the focuser.
In the included pic (img1) you can see it starts at 16sec, 8 sec 4 (which, so far so good) but as soon as it goes less no image returns. Both seeing and trans were average the night I tried.
So I put two questions to the group:
1. Any ideas on why the 4 sec limitation? I'd really like to be able to focus before trying to collimate.
2. Even when focusing manually I can't get a good result. Best I can do are these jellyfish stars. See img 2. Is this due to the mis-collimation?