Guiding Accuracy Doesn't Match PHD2

[Bill Richards]

[X ] Is the issue reproducible?
[X ] Are all prerequisites that are mentioned inside the manual met?

Which Version are you running? NINA version 1.10 HF3

Description

NINA displays very different guiding accuracy values than PHD2

Steps to Reproduce

• Use a NINA profile that includes using PHD2 for guiding
• Connect all devices, calibrate, and start guiding
• Compare the RA, DEC, and total guiding RMS values shown on the NINA display to those shown on the PHD2 display.

Expected behaviour

I would expect them to match, or be very close.

Actual behaviour

The differed by quite a lot, as shown in the attached screen shots. Have I overlooked a setting in NINA?

[Dale Ghent]

Can you spare us a larger screenshot that shows the NINA graph configuration which is completely cut off in the one you included?

Can you go to the Equipment > Guide screen and note the reported pixel size of your guide camera?

And which version of PHD2 are you running?

[Bill Richards]

Sorry - I failed to include the PHD2 version -my bad. I’m running 2.6.10.

I’ll have to wait until I have another clear night and set everything up again to capture the full screen shot you requested - I didn’t get the rest of it because none of it looked relevant. All it showed was y: +/-2”, x: 200 unit: ARCSECONDS.

Under Equipment > Guider, the Pixel Scale is shown as 4.98474. I have an ASI290MM (pixel size=2.9 um) attached to a 120mm guide scope so the image pixel size should be 4.98”/pixel. The imaging camera is an ASI2600MC-Pro (pixel size=3.76 um) attached to an Esprit 100 with an APEX 0.65 focal reducer, yielding a focal length of 358 mm and a pixel size of 2.17”/pixel.

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[Bill Richards]

I may have just figured out what happened. This is the first time I used this configuration (ASI290MM attached to a guide scope instead of an OAG). The way I configured it was to launch a similar NINA profile then go into PHD2 and modify the guide scope focal length. But that apparently doesn’t automatically update the Pixel Scale in NINA - you have to disconnect the Guider and reconnect it to get the correct Pixel Scale. I’ll try it again when I have a free night with clear skies.

[Bill Richards]

That was the problem - thanks, Dale!

[Bill Richards]

Wrong pixel scale from PHD2 (pilot error).