SharpCap Forums

I have a refractor (Apertura 72 EDR) - 72mm F/4.8. ASI533MC Pro - FOV of 1.88 degrees.

I just received the EAF and need some good settings for it.
I measured the backlash roughly @ 25+-5steps by monitoring the movement of the fine focus knob, so I set it in ASCOM properties panel.

I set the gain to 550 and exposure to 3sec. Average 2 samples (/2 seconds, whatever that means.)
The problem is that 100 steps away from perfect focus in either direction, Sharpcap focus assistant can no longer detect any stars. So I have about 200 steps of total range where the graph makes sense.
1) Does this result make sense?
2) Are there any settings that I can use to increase the range where stars are detected?
3) Should I use goto best position or go to best score?
4) Overall, what's your best fast procedure to refocus a slightly out of focus EAF due to temperature change?
5) Please give any other useful settings in Sharpcap.

Thanks.

Hi,

SharpCap's focusing is designed to get you from 'close to focus' to 'in focus', so it's not surprising that there is a limit to how far away from focus you can operate. That being said, detection of badly out of focus stars is much improved in SharpCap 4.0.

In general, goto best position is fine if your focuser moves in a reproducible way - that is if it is in the same place every time you go to position 12345.

If you want to refocus then a scan from -50 to +50 (or so) from the current position seems about right based on your info. This can be automated in SharpCap 4.0 using the sequencer as a single 'autofocus within XX points of current' operation - see https://docs.sharpcap.co.uk/4.0/#Focus

The combination of 'Average Over' and 'Samples to collect' determines how many frames at each movement step. I would recommend setting the 'Average over' to 1 frame and the 'Samples to collect' to 2 or 3.

cheers,

Robin