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FSQ-85 imaging distance

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Hello all,

Somewhere hiding in a corner of my house is a 6.8 mm Precise part adapter which was made to connect my FSQ-85 via the CA-35 to my QSI 683.  I can't find the danged thing.


If I'm not mistaken, the PP adapter was only necessary if using the FSQ-85 Reducer, which I am not planning to do at this time.  My understanding was that the FSQ-85's native petzval system wasn't as fussy about imaging distance as the reducer is.  Please humor me and tell me this is the case, or if I am incorrect, break the awful truth to me gently.  Odds are it will turn up any year now.

PS...as a fallback, I do have a 5mm PP adapter.  Close enough?


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You are absolutely right - If no reducer is used then no spacing requirement :)

If the spacing is 6.8mm for the reducer, then 5mm in my opinion won't cut it if you want round stars. I have found the spacing to be 0.1mm critical

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