Title: An Exercise in finding Backfocus on New Gear!
Description:
I Purchased an Optolong L-Ultimate 2" 3nm filter with a 2" Filter Tray.
This was the first time I used it on my 480mm scope with a X.8 Reducer.
I set the bvackfocus to 54mm as close as I could get to 55mm. After stacking
I noticed the backfocus was way off. All stars at the edge of the frame were
very elongated pointing to the center of the frame, which indicates the
camera is too close to the reducer. So on this 2nd image I shot 32 x 90 second
frames at 59mm backfocus. It was better but still the same problem so on the
next clear night I'll increase backfocus to 64mm and give that a try. Note: On
Image A I used an Optolong IR/UV Cut filter and that brought out the yellow stars.
On B Image I used the L-Ultimate and the blue stars are now more dominant.
Both filters have the same focus point.
Uploaded: ...
Title: An Exercise in finding Backfocus (found at 65mm)
Description:
This is the final image my Back-Focus is 65mm or that's as close as I'm getting with my
80mm with the reducer. I have a total of 3 hours 20 minutes integration time with both
65mm and 59mm backfocus images used.
Uploaded: ...
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