Hello! I’m checking to see if anyone uses a ZWO EAF on a Meade LX200 classic. I’d like feedback on the parameters used in the SGPro autofocus routine.
I updated the Robofocus to an EAF. I use SGPro4 and Windows 11. I deforked the 8” LX200 tube and attached it to a Ioptron HEM44 mount housed at Starfront Observatories in Texas.
Autofocus is erratic. The half flux diameter does not seem to move for several moves of the EAF before finallyu engaging. I’ve gone through the AF routine to try to identify the HFD change with defocus in order to set the step parameters, but there is no consistency. I also tried setting different moves settings (9 in total as recommended) from 50 to 400, all with the same results
I’ve asked Starfront observatories to check the connections for slippage since they installed the focuser. However, if anyone is using an EAF on and LX200, I would appreciate guidance as to what parameters you use. Thank you.
I have imaged with a Meade OTA (mostly the ACF format) for many years and while the optics are excellent, the internal focusing mechanism leaves a lot to be desired. Based on your post, I assume your EAF is directly attached to the internal focusing knob. I have also used an EAF focuser but it was attached to a Feathertouch Rack and Pinion focuser.
You have two issues here. The internal Meade focuser has a large amount of backlash and the EAF has a rather large amount of movement per step. So, first off, configure the EAF or SGPro to use a lot of backlash – perhaps 60 to 80 steps. Try using just 7 focus frames. On a failed focus, examine the focus images to see what is happening. If donuts are present, those must eliminated. Also, use the ASTAP focusing software, as it is quite accurate.
Before trying an autofocus run, be sure to get an excellent focus manually. Then examine the autofocus frames to see what the autofocus routine does.
The most reliable way to use a Meade OTA for imaging is to NOT use the internal focuser. Use the internal focuser only to position the back focus and then lock the mirror. For focusing, you really need to use an external, low profile focuser as the Meade has an optimal back focus of only about 6.5”. The low profile, 2” focuser from PrimaluceLab would be a good choice.
I use the Optec Gemini Focusing Rotator on my 12” Meade LX850 ACF with very low profile adapters to get the camera to that 6.5” optimal back focus point.
Also, I seem to have the problem others have noted - the autofocus retry seems to fit well, but is below the 90% accuracy level, so autofocus fails. I see the new beta version may have corrected this. Thanks.