PHD2 Settings for iOptron HA:R43EC Mount

Hi Don,

I just grabbed a screenshot of settings I use with my CAT91 rig.

📷 HAE43EC Settings.jpg

I run multiple rigs on my HAE43EC mount from the CAT 91 to larger Stellarvue 4 and 5 inch refractors. Sometimes even my EdgeHD 11 and it works fine. I’m just not comfortable with that large of a scope on the HAE43EC mount. Sometimes I use an OAG and sometimes guide scopes. The only thing that changes with the main scopes or OAG vs Guide Scope in the PHD2 settings is the Min Move amount and focal length. I calculate MinMove for each rig I use. You can use this site for a guide on calculating your Min Move setting https://www.myastroscience.com/minmoveinphd In all cases I use 1 sec guide pulses because that gives the best result for me in terms of lowest RMS error. Up to 3-4s guide pulses have given acceptable results with my gear. RMS error values for me are typically 0.05 - 0.15 pixels or 0.3 to 0.5 arcsec depending on what number you wish to use for reference.

My HAE43EC is one of the first built that requires PC connection through the hand control. If you connect directly to your mount you may need to enable the “Reverse Dec Output after Meridian Flip” button. I’m actually not certain on that for the HAE43EC but it is the case for my newer HAE69EC mount that does not use the hand control.

An issue I found initially with mine was belt tension was too loose on both axis. Here is an iOptron document you can reference on that if adjustment is needed. HAE_Backlash_ADJ.pdf

Two more things I just thought of to check. Make sure you have initially calibrated the RA encoders. Also make sure that RA guiding is enabled in the mount settings. I believe it defaults to off. Directions for both of these can be found in the manual.

Hope something here helps. There are actually a ton of things that can cause you grief guiding. It would help to know the actual gear you are using as well as the issue you are seeing as detailed as possible. This is a great site for help.

Good luck and clear skies,

Jeff

I added a couple comments possibly after you first read my post sorry. Did you do the initial calibration on the RA encoders and is RA guiding turned on in mount settings? If you saw those already I apologize. Might explain the error you are getting especially if RA guiding is off.

Jeff

Don Norwood · Nov 27, 2025, 03:29 AM

Here is the link to the logs. Thank you.

https://drive.google.com/drive/folders/1YJo63Pc6jYmonAXbXtHlm2HSOD6JLSKU?usp=drive_link

Don, have you had success with your PHD2 settings? I am looking forward to trying Jeff’s settings next time I get some clear skies. It's really hard to find many posts about the HAE43EC, so I appreciate what you started here.

That’s a little better than what I get. I think these mounts can do better, though. I notice you're doing 3s exposures? Have you tried lower? It seems counter intuitive to me, especially with 2.1as seeing, but when I went from 3s to 1s, guiding improved quite a bit for me. I've never tried low pass on the RA axis. Gonna give that a shot if I ever see clear skies again.

Tom Utendorf · Feb 6, 2026, 06:13 AM

That’s a little better than what I get. I think these mounts can do better, though. I notice you're doing 3s exposures? Have you tried lower? It seems counter intuitive to me, especially with 2.1as seeing, but when I went from 3s to 1s, guiding improved quite a bit for me. I've never tried low pass on the RA axis. Gonna give that a shot if I ever see clear skies again.

I purchased this mount with the goal of being able to use longer guide camera exposure to help ensure enough stars for off axis guiding in my often, less than optimal seeing conditions. Many say that any exposure less than 3 seconds causes conflicts with the RA encoder. That being said, if it works it works. I do now understand why some people choose the non-encoder version.

Don