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EdgeHD 8" w/Celestron Focal Reducer - Stars Distorted in OAG

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#51 michael8554

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Posted 28 September 2022 - 06:26 AM

Hi Domer

 

Looking at your grabs in post #44.

 

Your Cal problems are probably not due to the OAG, but due to the comments in the PHD2 message:  PA, Dec Backlash etc.

 

Because in my experience at 1400mm FL, and other's, PHD2 will cope well with misshapen OAG guide stars.

 

Post the GuideLog.



#52 tomb18

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Posted 28 September 2022 - 10:06 AM

Which zero OAG are you using? If it's the large one, it will never get in far enough.
Been there done that.

#53 Domer

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Posted 28 September 2022 - 11:14 AM

Hi Domer

 

Looking at your grabs in post #44.

 

Your Cal problems are probably not due to the OAG, but due to the comments in the PHD2 message:  PA, Dec Backlash etc.

 

Because in my experience at 1400mm FL, and other's, PHD2 will cope well with misshapen OAG guide stars.

 

Post the GuideLog.

The discrepancy in RA and Dec guide rates and backlash are artifacts of the guide star center of mass jumping all over the place due to the guide star being misshapen.  I can see the little red crosshairs in the PHD2 display jumping every which way during calibration, causing it to think the star is moving in ways that it is not.

 

When I replace the EdgeHD with my Esprit 100 and ZWO OAG, I get near perfect calibrations with the same mount (and very similar payload weight).


Edited by Domer, 28 September 2022 - 12:51 PM.


#54 Domer

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Posted 28 September 2022 - 11:17 AM

Which zero OAG are you using? If it's the large one, it will never get in far enough.
Been there done that.

I have the "Celestron 93648 Deluxe Off-Axis Guider".  Is that the wrong one to be using?  That's the only one on the Celestron web site.



#55 Peter in Reno

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Posted 28 September 2022 - 01:23 PM

I have the "Celestron 93648 Deluxe Off-Axis Guider".  Is that the wrong one to be using?  That's the only one on the Celestron web site.

I think he meant "ZWO" when he typed "zero". Must have been auto corrected to "zero".

 

You picked the correct Celestron OAG.

 

Peter



#56 Domer

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Posted 28 September 2022 - 01:27 PM

I think he meant "ZWO" when he typed "zero". Must have been auto corrected to "zero".

 

You picked the correct Celestron OAG.

 

Peter

Ah, that makes sense.  I almost purchased that large ZWO OAG a few months ago and realized that it was too large to accommodate my filter drawer so I didn't buy it.



#57 hornjs

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Posted 29 September 2022 - 08:02 AM

It does boggle the mind how many problems there are with the celestron 0.7x reducer, especially for the $400 price tag.  Mine has bad chromatic abberation.  Probably gonna try the f/10 route next as mentioned above.


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#58 schellaj

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Posted 29 September 2022 - 08:37 AM

It does boggle the mind how many problems there are with the celestron 0.7x reducer, especially for the $400 price tag.  Mine has bad chromatic abberation.  Probably gonna try the f/10 route next as mentioned above.

I totally agree. I just switched back to F/10. I sent my reducer back to Celestron and they are shipping me a new one (even tho they say the images I sent them are within spec). I'll give the new a try when I get it. It really comes down to the blue channel and the aberration there. I can mange nice round stars to the corners of my QHY268M (APS-C) with LRG but the B sucks.

 

I wish Starizona would make a reducer for the EdgeHD 800.  They are supposed to be releasing a F/4 reducer for the Edge at some point.

 

Jason


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#59 DirtyRod

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Posted 29 September 2022 - 11:28 AM

I totally agree. I just switched back to F/10. I sent my reducer back to Celestron and they are shipping me a new one (even tho they say the images I sent them are within spec). I'll give the new a try when I get it. It really comes down to the blue channel and the aberration there. I can mange nice round stars to the corners of my QHY268M (APS-C) with LRG but the B sucks.

 

I wish Starizona would make a reducer for the EdgeHD 800.  They are supposed to be releasing a F/4 reducer for the Edge at some point.

 

Jason

Celestron told me Monday they are going to replace mine for a tilt issue but told me they won't have any more in stock until April 2023. Amen on Starizona. 


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#60 hornjs

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Posted 29 September 2022 - 11:37 AM

Just out of curiosity, is your reducer still under warranty?  I am well beyond mine and purchased mine on the classifieds here since there was a huge backorder time when I was purchasing (start of pandemic)

 

Wonder if it would be much harder to find a guide star at f/10

 

I totally agree. I just switched back to F/10. I sent my reducer back to Celestron and they are shipping me a new one (even tho they say the images I sent them are within spec). I'll give the new a try when I get it. It really comes down to the blue channel and the aberration there. I can mange nice round stars to the corners of my QHY268M (APS-C) with LRG but the B sucks.

 

I wish Starizona would make a reducer for the EdgeHD 800.  They are supposed to be releasing a F/4 reducer for the Edge at some point.

 

Jason


Edited by hornjs, 29 September 2022 - 02:59 PM.



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