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IEXOS-100 can't get round stars due to RA erros? #iEXOS-100


NewAP
 

Have IEXOS-100 for over a year, used for unguided imaging, and noticed that I could not get round stars, it was always elongated along RA.
Thought moving to guided imaging will resolve this issue so did the move recently, still can't fix egg shaped stars.

Imaged with Canon 6D at 300mm, 600mm over 30 sec, 60 sec. Tried to tweak the pulse rate from 0.4 to 0.5 and 0.6 without any major improvements.
Still get elongated stars, for bright stars the trails are so obvious.

I removed the motor covers and noticed that the DEC pulley seems to be more smooth than the RA pulley, which is definitely not acentric so well, but not sure if that could be the cause.

PHD2 reported RA peak-peak 30-50 seems to be OK. RA RMS errors seem to be reasonable as well (1.x arcsec/s), but the drift limited exposure was very low in the 0.3-0.7 second range.
PHD2 logs have been uploaded, so are some sample pictures.

Please help and suggest. Quite confused and thought maybe I am unlucky the unit has problems with RA tracking?

NY
--
Canon 6D, Sigma 150-600mm, IEXOS-100


brian skinner
 

Hi there, I may be wrong here of course but it looks to me that your problem could be bad focusing??
--
Brian Skinner
iEXOS100
Canon 1300d dslr
Various lenses
ES Polar scope
Sequator image stacker
PIXR image editor


NewAP
 

Hi Brian, thanks for the input, I thought about it a bit, the focusing was not perfect but it always showed up along RA direction, so I suspect the RA movement has some impact, and it is true we can't rule out the possibility of lens or focusing.

Yi  

On Fri, Jan 8, 2021 at 10:02 AM brian skinner <brianjimskinner@...> wrote:
Hi there, I may be wrong here of course but it looks to me that your problem could be bad focusing??
--
Brian Skinner
iEXOS100
Canon 1300d dslr
Various lenses
ES Polar scope
Sequator image stacker
PIXR image editor


Wes Mcdonald
 

Yi

1.  I saw PHD recommended you focus your guide camera.  PRobably should do that.

2.  MAke sure your guide star is not saturated.  

3.  Dont use PEC algorithm, ust go with the normal ysterisis and resist switch I believe.

4.  MAke sure your PA is pretty go so you do not get field rotation.  Field rotation will make the stars look like this even though the guiding is good.

5  What did you say your RMS total guide error was?  1.x arc seconds?  This is excellent.

If your RMS guide error is low like that then you have terrible PA.  

Ask PHD to evaluate your PA.  How are you polar aligning?

Just some thoughts.  

Wes.




--
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired