OAG, Field Rotator, and PHD2

[Clayton Yendrey]

I think I know the answer already, but thought I get some input from the experts to make sure I wasn't assuming something that wasn't true.

I have an Esprit 100ED w/Moonlight Express Nightcrawler focuser/field rotator.

To this point I've always used a separate guide scope which has performed well.

I've been considering an OAG and have been trying to understand the ramifications this would have on my setup/workflow.  (MyT mount, TSX mount driver via ASCOM, NINA sequence management, PHD2 guiding).

I had almost convinced myself to go ahead with the OAG, but then started considering the effects of my framing of the targets (field rotation) vs PHD2 calibration.  If the calibration process works like I think it does, when using an OAG, PHD2 would have to recalibrate everytime the target framing changed (field rotation changing relative to mount axis).

Am I correct on this?

[bw_msgboard]

You're correct as far as you went :-)  In order to avoid having to recalibrate every time, PHD2 supports use of any ASCOM compatible rotator.  It's one of those "extra" devices that you see when you click on the expansion control in the Connect Equipment dialog and it's discussed in the manual.  Most of the available rotators are ASCOM compatible so you should be ok - but you should probably confirm before buying more gear.

 

Have fun,

Bruce

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From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of Clayton Yendrey
Sent: Monday, January 10, 2022 11:37 AM
To: Open PHD Guiding
Subject: [open-phd-guiding] OAG, Field Rotator, and PHD2

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[Clayton Yendrey]

Bruce,
When you say PHD2 supports the ASCOM rotators to avoid recalibration, what does that mean?  (FYI, the Moonlight Express Nightcrawler is ASCOM compatible as well has having native drivers in Windows and for TSX).  Is PHD 'seeing' the rotator angle information and adjusting the calibration orientation automatically?

[Brian Valente]

>>> Is PHD 'seeing' the rotator angle information and adjusting the calibration orientation automatically?

correct

here's my PHD setup for the planewave IRF90 rotator. I never think about adjusting for rotation, PHD calculates it for me

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Brian 

Brian Valente

portfolio brianvalentephotography.com 

[Clayton Yendrey]

Cool,

I may have to give OAG a try once I'm done with my RA/Worm assembly replacement/test.

[Bryan]

I reduced the RMS from 1"" to 0.4" - 0.6" switching from a guidescope (400 mm) to an OAG.  The biggest challenge is focusing when the pickup mirror presents such a small FOV.  If your guide camera is sufficiently sensitive, there will not be any problems.

Bryan