Will a 17mm ethos and 30mm Pentax xw vignette with a 35mm baader t2 diagonal

[GavStar]

Hi all,

My biggest fov eyepieces are a 17mm ethos and a 30mm Pentax xw. I have a baader t2 Zeiss prism diagonal which at 35mm is bigger than a standard 1.25 inch diagonal (about 30% bigger I think). However I'm not sure whether this is big enough to avoid issues when using the ethos and Pentax. If anyone could confirm how to work this out, that would be great.

Thanks

Gavin

[Stu]

The field stop on the 17mm Ethos is 29.m so should be fine. I'm fairly sure I've used a 31mm Nagler with mine and the vignetting is not really that noticeable visually.

[GavStar]

Thanks Stu. I've just found out that the field stop of the 30mm Pentax is 36.2mm (identical to the 21mm ethos). So it will vignette a bit but I guess pretty limited?