Quote:
Originally Posted by alocky
Hi Josh - that's kind of what I'm getting at. If it is flexure in the optical train, the guide chip should be guiding it out. If the guide graphs are that good, then the guide chip isn't seeing the same movement as the imaging chip.
Only external-to-camera things I can think of are vibrations at a frequency higher than the guider will register, but they are unlikely to induce a linear error. Have you tried turning off the cooling fans?
Anyway - good luck!
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Andrew, yeah i will try it without the cooling fans on. interesting thoughts re flexure there. thanks.
Quote:
Originally Posted by PRejto
Hi Josh,
Well, you have a lot of input here! Why not take very short unguided exposures and check this out? Wouldn't that just eliminate one complication? With a mount like yours and good PA you shouldn't see anything except round stars in 5 sec or so! Obviously then if you don't see the error it leads back to guiding, no?
Perhaps a statistical analysis using CCDInspector would help by comparing aspect ratios at different points in the sky (with short exposures). With everything secure you probably shouldn't see any change in aspect as long as focus is holding while you slew.
Peter
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hi Peter,
Yes, although my 30 sec unguided exposures showed exactly the same results as my guided 60 sec exposures, i will definetly do some 5 or so sec unguided images when the clouds clear.
thankyou all.
Josh