FSQ85 radial star elongation - Fixed!

[SyedT]

Hi all,

I recently made a thread regarding my FSQ85 showing radial star elongation in the corners: 

I'm very appreciative of all the input I received, and it's why I say SGL is simply the best forum for astrophotography. It was suggested that I try the dedicated 1.01x flattener, and Ian King suggested this too, stating that the FSQ85 was primarily designed for cameras with larger pixels (I use a QHY163M which is 3.8 microns and high-resolution). I ordered the flattener and have put it through its paces. I've noted a very significant improvement on initial testing; there's some tilt on one side but I suspect that's the focuser, which I find in my case is poorly built. It has lateral slop and a rather rough action as I'm unable to autofocus properly due to image shift. May think about a Feathertouch, but that's yet another hefty investment (if anyone has a spare one going I call dibs!). I've attached an example of a sub without the flattener (top), and then with the flattener.

Thank you all for your help!

 

[Skipper Billy]

It's a bit much having a premium scope that needs a focuser upgrade to work properly. I must admit that I would be more than a little upset! 

 

 

 

[SyedT]

7 minutes ago, Skipper Billy said:

It's a bit much having a premium scope that needs a focuser upgrade to work properly. I must admit that I would be more than a little upset! 

 

 

 

Completely agree, there isn't really an excuse. I did get it second-hand for a reasonable price (which of course still doesn't excuse anything), which is why I'm mulling over a Feathertouch. I was very surprised about the lateral slop, and the image shift is a pain as it throws off the focus significantly. I had the same Lakeside motor attached to my RC6 and GT81 previously and they both worked perfectly with minimal shift.

[nicoscy]

Syed,

I found this somewhere - it may help. Your stars by the way do show massive improvement with the flattener

CAA adjustment.pdf

[ollypenrice]

23 hours ago, Skipper Billy said:

It's a bit much having a premium scope that needs a focuser upgrade to work properly. I must admit that I would be more than a little upset! 

 

 

 

I entirely agree.

I'm at a bit of a loss to know where pixel size comes into the story but will be happy to read an explanation.

Olly