Big scope eyepieces

[Jim!]

Hey guys and girls, quick question.

The longest focal length eyepiece that I can find is the 2" Meade 56mm 4000.

If I have a monster sized newtonian, 30" F6 (f/l 4.5m) that'll give a magnification of x80ish.

Is a lower magnification achievable with 2" eyepieces, or will I be limited with 3" or even 4"?

Thanks very much, Jim

[oceanheadted]

Jim,

even at 80x won't you end up with a massive exit pupil (a typical dark adapted eye is 7mm at 80x you will have an exit pupil of 9.5mm if my numbers are right) with a 56mm focal length eyepiece, so you will be wasting the light/ not seeing the whole image,

regards

Alan

[John]

Jim,

Alan is right - a 56mm eyepiece is not a great idea in an F6 scope. 40mm would be OK - the Panoptic 40mm would be very nice !.

I've seen a few 4" eyepieces being discussed from time to time on other forums but they are very specialised bits of quipment - Zeiss do one but that costs $thousands. Siebert Optics also do larger occulars:

Siebert Optics - Observatoy series

[Jim!]

Thanks guys, I forgot about exit pupil size

So in effect the F ratio limits the minimum magnification of the instrument due to the exit pupil size.

I guess the instrument is still ok to use with a 10mm exit, but you may as well use a smaller

scope becuase the eye can't collect all the light.

[yesyes]

WOW, those are massive eyepieces... ;-)

but their website looks rather retro, like hand coded HTML... :-/

Regarding exit pupil, wouldn't that also depend on the AFoV of the EP? If they would make the long focal length EPs with a narrower AFoV, it should reduce exit pupil size, no?