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ZWO FF107 poor star test

ZWO FF107 107mm f/7 Petzval Refractor Refractors Troubleshooting
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Paul Degtyarev avatar
Paul Degtyarev avatar
I recently acquired this scope. Frankly not super impressed with visual image quality, given the price. When doing a star test I see well formed airy disks on in-focus star, but mushy barely any disks on out-focus side. This seems to indicate  a major spherical aberrations, under-correction.
Can anybody confirm  on his FF107 that it is a problem?
Thanks.
AstroShed avatar
AstroShed avatar
This is the exact same scope as the Askar 107PHQ I believe, and I have read a few similar issues with that one, and it seems to be due to some slight mis collimation of the built in flattener, but not something you can put right yourself…☹️
Ed Dixon avatar
Ed Dixon avatar
Not seen any issues with the one I have.
powdermillphotography avatar
powdermillphotography avatar
I have the FF107 as well and have been frustrated with seemingly out of focus stars as well, always attributing the problem with my own lack of focusing skills and ineffective way of keeping the focus (that little focus tensioner at the bottom of the focusing assembly). Your report is concerning to me about how much of this problem is correctable.
Harold Soto avatar
Harold Soto avatar
Hello, I have the identical scope and have used it with both the native focal length and the reducer. When utilizing the reducer, it is critical to have the correct back focus. I used a back focus adjuster to make it nearly perfect. Is the sharpest scope I currently have. It is the same as the Askar PHQ Series. You can see some of my photographs from this scope. If the item is still under warranty, you may wish to return it.
Concise
JanHeremans avatar
JanHeremans avatar
I do not have any problems with mine. I am not using a reducer.
CS, Jan