you can use one 1.25" filter on the 294 with the help of 1.25-T2 adapter
Yeah I think we could, sometimes
. Other times we shouldn't
. And other times again, we can't
- Ok if the scope is not faster than f/4 or so, and there's enough room for the relatively high 1.25" cell filter plus adapter, and the sensor is not bigger than 4/3.
- Not ok with fast instruments like a f/2 Hyperstar setup, much more vignetting introduced in a case with relatively bad inherent vignetting.
- Many mFT lenses are of great value and quality, but could only be used, with a 1.25" filter and the 1.25-T2 adapter, if the filter cell above the threads are 4.0mm or less
. Have not come across anything lower than 6.0mm.
Sam, can I please have the exact protect window (glass) measurements?
I'd say ZWO is specializing in cameras, wouldn't expect that you have all kinds of filters!
(ASI camera body design housing a protect window based on standard filter sizes, like unmounted 31mm and 36mm, would be great)
It's only EUR 55 extra, plus long wait, to have custom size filters, as long as the thickness matches reasonably.