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PHD star did not move enough

Veracocha

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Veracocha

Veracocha

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This is a concern but I hope I may have answered my own question. Is it possible to be so accurate with PA that PHD cannot calibrate due to good tracking? For three weeks I have been tailoring my PA procedure and I believe it is true as can be and with a reticle 10mm eyepiece the stars just haven't moved for at least 30 minutes into the current session.

I am tempted to put my moded 350D on but without a much needed CLS-CCD filter it's not going to help much. Any idea's?

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Zakalwe

Zakalwe

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AFAIK, PHD commands the mount to move so it can calibrate which way is "up", which way the camera is orientated etc. So if the star hasn't moved, then I'm with Glider...you have selected a hot pixel. I find that whacking the exposure or screen gamma up quickly shows which are hot pixels and which are stars. or, you can give the mount a nudge using EQMOD and see if the "star" moves.

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Veracocha

Veracocha

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Guiding on a dead/hot pixel?

Definately not a hot pixel, various stars to choose from but result is the same. I will ramp up the calibration steps but if the star in the imaging scope remains so central in the eyepiece does that not mean the tracking is working well? Thanks for the help guys.

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rocketandroll

rocketandroll

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nope... good tracking won't result in failed calibration. During calibration it slews the mount a set distance in each axis to confirm the mount is receiving guiding commands and to check orientation. The star is MEANT to move... if it doesn't, something us wrong.

Try upping the max duration, see if that helps...

I had this problem and ultimately found it was because there was a fault with my guide port. hopefully your issue is less serious.

Ben

Sent from my GT-I9100 using Tapatalk

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Zakalwe

Zakalwe

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nope... good tracking won't result in failed calibration. During calibration it slews the mount a set distance in each axis to confirm the mount is receiving guiding commands and to check orientation. The star is MEANT to move... if it doesn't, something us wrong.

Try upping the max duration, see if that helps...

I had this problem and ultimately found it was because there was a fault with my guide port. hopefully your issue is less serious.

Ben

Sent from my GT-I9100 using Tapatalk

^^ This^^

Good polar alignment will result in a very flat PHD graph, as the application is not having to make many adjustments. The star will still move it's position in the window during calibration.

Make sure to use an exposure lentgh of 1.5 seconds or above, otherwise you are chasing the seeing.

Also, you have selected ""Camera> On mount" in the PHD menu amd plugged the ST4 cable from the guidecam into the mount port?

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Zakalwe

Zakalwe

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Another thought....what are you using as a guidescope? I used to use an 80mm frac but moved to a finderguider. i had to changes some details in PHD as the widefield of the finderscope wasn't working during calibration.

If you are using a finderguider then a search on here or on Google will get you the correct settings.

HTH

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riklaunim

riklaunim

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You are spawning cases like crazy :icon_confused: Usually is that on low focal lengths the pulses on calibration must be long for the star to move sufficiently - that's why long calibration step duration is needed.

ST4 disconnected or other bad settings would show up much sooner than this one :rolleyes:

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Veracocha

Veracocha

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Went up to 2000ms, tried everything but still star does not move enough. I intentionally tried upsetting my PA by a small margin and the star would move enough for it to calibrate W.E.N.S after a count of 15 steps but as it started guiding the star would drift well out of the square. So frustrating.

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riklaunim

riklaunim

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At 2000 ms pulses at calibration the star should easily move by 1/3 of the guide camera FOV. Listen to the mount when it's calibrating - if the signals go to the mount the motors sound should change per every test PHD makes during calibration (if it does then - the problem will be in the mount like backlash or not locked axis... or something like a very big hot pixel)

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Veracocha

Veracocha

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At last, almost there and here's my first half decent graph. After trying every setting possible in PHD I switched to pulse guiding. I went into EQMOD and unchecked/rechecked the "pulse guide perameters" and here;s what I achieved. Tomorrow night I will revert back to ST4 and try unchecking the ST4 settings as above. I can't tell you how happy I am atm.

post-23287-13387770305_thumb.jpg

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Uranium235

Uranium235

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Did you "nudge" the mount before calibration? What works really well is if you nudge North before starting calibration (it removes the "clear dec backlash" step). If your ST80 is in adjustable guide scope rings, make sure its all nice & tight - or swap to fixed rings.

You can increase your max dec to 200, I usually run at 250 as im on a finderguider. Another thing that works well is one of those cheap 1.25" 0.5x reducers, you can reduce the ST80 to give you a bigger choice of guide stars.

But if you can nail your PA to start off with, it will give PHD a lot less work to do.

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