36mm Filters

[TrevorW]

If you have a APS-C size sensor would using 36mm filters cause any vignetting ???

[Startrek (Martin)]

Trev,
Here ya go …..,

https://astronomy.tools/calculators/ccd_filter_size

Martin

[TrevorW]

Thanks Martin according to that calculator it should be OK

[Startrek (Martin)]

I use 2” unmounted filters in my ZWO 7x2 filter wheel with ZWO 2600MM and 2” filter drawer in ZWO 2600MC ( APS-C ) at 55mm BF and I have severe vignetting in both 8” and 10” Newts
Reason ?
My TS Optics GPU coma corrector shifts the focal plane by a good margin therefore at lest 20% of my field is not lit , mostly in the corners but marginally all the way around.
Vignetting is the trade off for a damn good coma corrector ( F6 to F4 ) which perfectly corrects coma to edge of field. ( cost as new $600 )
Calibrated Flats are worth gold in my imaging

Cheers
Martin