|
Hi Joe,
The general consensus is that 1.25" filters will not provide full illumination for an APS-C chip, so you will get some vignetting.
I found this thread from Stargazers lounge that may be helpful :-
You can calculate the minimum filter clear aperture required for full illumination using the formula:
minimum filter size = CCDdiag*(FL-DC)/FL + (DC/f), where FL is focal length, CCDdiag is the size of the chip diagonal, DC is the distance between the chip and the filter, and f is the focal ratio of your scope
Be aware that the minimum size here is the clear aperture not the overall filter size - a typical 1.25" filter has a clear aperture of around 28mm depending on manufacturer whereas the 36mm unmounted Baaders have a clear aperture of nearly 36mm
Cheers
Bill
|