ASI Air Calibration, Please Help!

calibiz

Hello.

So I've been having a lot of trouble trying to get my setup calibrated with my ASI AIr Pro.

I have a William Optics GT 71, an ASI 294 MC pro. an ASI 174mm mini, and a WO 50mm mini guidescope (200m FL), with an HEQ-5 Pro.

A week ago, my setup miraculously calibrated perfectly and ran perfectly all night. The calibration steps basically stayed perfectly in line with the calibration distance. 1 step per 1 calibration distance, north south, east and west. it was beautiful. The calibration step would finish right alongside the calibration distance.

But the past 4-5 times I've taken my setup out I cannot get my setup to calibrate to save my life. I checked the balance, it seems about as perfect as I can get it. I adjusted the focus on the guide cam, seems good to go.

When I start the calibration, the "east west" Distance to Step ratio is about 1:1. It eventually settles both back at 0 in time to start the North/South calibration step. Seems perfect. Crosshairs right on the star as it begins the North South. All is well.

THEN, everything goes to hell during my North/South calibration step.... Heads north to about 52 steps, 26 distance. Then for some reason, every time as it comes back to the star, the "south step" speeds past the "south distance". Steps go from 51, 50, 49...Seems fine, but when I check the distance, the distance is barely moving. So it will go from (51 step, 25 distance)...(45 step, 24.9 distance). (40 step, 24 distance), until eventually it's at (1 step, 7 distance.) It then "completes" the calibration with a distance of 7, and the crosshairs are nowhere near the star. My guiding afterwards is of course, horrible.

Any idea on what's causing me these issues? Below is a screenshot of my guide view.

https://imgur.com/b4RvODS

w7ay

calibiz Steps go from 51, 50, 49...Seems fine, but when I check the distance, the distance is barely moving.

"Step" counts are simply a count of how many pulses are issued from the software to the mount. Distance is the actual measured movement in the capture guide frame.

It almost sounds like your declination axis has a huge backlash at certain declination angles. I.e., declination (north-south) pulses are being issued after the reversal, but the mount hadn't actually moved. Check the declination gear and belt, perhaps?

To check, try going somewhere else (at least somewhere with a diffrent declination angle) and calibrate there (you actually should calibrate at declination = 0º) to see if this problem goes away.

Chen