Quote:
Originally Posted by gregbradley
I looked at the Rosette Luminance. That's tilt. You don't have coma in all 4 corners but rather only 2 left and right top and bottom.
My advise is to get rid of the CAA. That's what the difference is between the EDX111 and the EDXiv. It was replaced with a solid casting. The CAA is not good enough.
An alternative is to replace the whole FSQ focuser with a Feathertouch 3515. They make a specific focuser replacement for the FSQ.
Tak brought out EDX1-4 in an attempt to fix these sorts of problems. If you send it back to Tak they are likely to tell you the scope is within design parameters.
Having a tilt adapter is not going to help if the flex is coming from the CAA in front of it.
Another point. The lock focus lever on the EDX scopes is defective. If you engage it you will get a shift of focus. You either don't use it at all or have it half engaged, focus then fully engage and it won't shift focus.
I have had an EDX111 myself I bought new and also an FSQ106N which had a much sturdier focuser and a simple but problem free focus lock.
Tak may be great for optics but they are no AP or Feathertouch for focusers.
Greg.
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Quote:
Originally Posted by gregbradley
The QSI sensor (KAF683) micro 4/3rds size is less than half the size of the ASI6200 -full frame 36 x 24.
So you the centre stars are always sharper than the outer stars. Star sizes get larger the further out from the centre you go.
Its not a focusing issue its a tilt/flex issue.
By the way Rodney the 178mm is the backfocus. FSQ is a flat field scope meaning there is no optimum spacing for the imaging components so long as its less than 178mm.
Greg.
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Thanks Greg, yep - I'm fine with the fact that the OTA should have a flat field at 178mm backfocus which is consistent with my observations thus far. This is why I was a surprised to see such an obvious radial pattern in the field.
From my review of the images, the radial pattern to me looks to be too consistent in the corners to blame tilt at this point. I am happy to be proved wrong of course. I even used the Dynamic PSF tool in Pixinsight to measure the ratio of x/y coordinates of the stars in the corners and they all looked to be the same to me.
Having said that, when I bought this scope I had in the back of my mind that I wouldn't be surprised if I finished up changing the stock focuser as I have been down this path with my TSA120. I fought with that scope for 18 months before finally buying a Feather Touch focuser for it and I have never looked back. I would really want to be sure that the optics are up to scratch first though before spending that sort of money on this one.
I do have a spare Moonlight focuser sitting around that I might try. I would just have to buy the adapter from them to match the FSQ. Would be a cheaper option to check it before taking the plunge.