Biggest true field for a 2" ep

What ep will deliver the biggest true field in a 2" focuser ? Maybe the 40mm Meade SWA ? (67degres)

Thanks,
Andre

According to Uncle Al, it's the 41 Panoptic.

Don W

When it comes to determining the true field of view of an eyepiece, one needs to measure the field stop, which actually determines the true field of view. Of course one can also use the drift method or measure starfields.

The formula TFOV = AFOV/Mag is a first order approximation with several assumptions that are not necessarily valid so even if the manufacturer is honest and does not exaggerate the AFOV, the actually TFOV may be significantly less.

The ID of the filter threads on a 2 inch eyepiece is about 47mm so this is the limit of the TFOV.

As far as which eyepiece actually provides the greatest TFOV, I cannot say, I haven't measured them though I think the 41mm Panoptic and some of the 50+mm plossls are competitors..

Jon

Any of the following will be very close:
41 Pan
40 Pentax XL or XW (XW a bit closer than XL)
55mm Plossl (watch for exit pupil issues)
40mm erfle variants (GSO, Konig, etc.)
40mm SWA

In a fast scope, I would stick to the Pentaxes and Panoptics - the others will have astigmatism.

In a slower scope, the erfles, SWA, or even the plossl may be cheaper alternatives.

Jarad

Andre: In another thread you indicated one of your scopes is an 80ED. Last year I also wanted a big field of view for my 80ED in order to have a true field of view that would take in the entire Veil Nebula or the entire Andromeda Galaxy. Not having any desire to pay hundreds of dollars for any of the high-end TeleVue eyepieces, I bought a BW-Optik 30 mm Ultrawide (APOV 80º) for less than $100 from Anacortes. It gives me a 232 arcminute TFOV in the 80ED and works fine, if you can accept something less than perfect performance around the edges.

41mm Panoptic I believe.