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Old 06-04-2014, 01:33 PM
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jwoody (Jeremy)
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Join Date: Aug 2011
Location: Ormeau Hills, Australia
Posts: 374
HoTech field flattener for ED80/QHY8pro. Have I got this right?

Hello everyone.
I use a QHY8pro and a Skywatcher Evo 80ed scope but I am not happy with the misshapen stars in the corners. Looking around at field flatteners I have settled on the HoTech 2"SCA field flattener from here:
http://agenaastro.com/hotech-2-sca-field-flattener.html

It requires 56mm of back-focus to the camera CCD. According to the QHY8pro manual the CCD has 20mm of back focus therefore a 36mm spacer is required, no problem.
However, my QHY8pro differs from the one mentioned in the manual (maybe mine is an earlier revision, I am not sure). My camera doesn't have the tilt/centre adjustment or the hole for the desiccant tube.

So I am a little confused as to what extra spacing I require so maybe I should just get this :
http://agenaastro.com/baader-variloc...e-29-46mm.html

From what I can see the combination of these two should do the job. Have I got this right or is my understanding of back-focus completely wrong.

Thanks
Jeremy

Last edited by jwoody; 06-04-2014 at 04:24 PM.
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