Eyepieces - Exit pupil

[Sarge (Rod)]

I have a 12" collapsible Dob and am about to upgrade my eyepieces. I was considering purchasing a Televue Panoptic either 35mm or 27mm. My concern is the exit pupil of the 35mm in my scope is 7.1mm and the 27mm is 5.4mm. Is the 7.1mm exit pupil a problem and if so how much of a problem?

Rod

[koputai (Jason)]

Most people will speculate that it won't work, the exit pupil is too big, but I have a 12" Dob and the Pan 35 works great in it. A beautiful eyepiece.

Cheers,
Jason.

[ausastronomer (John Bambury)]

Hi Rod,

It depends entirely on the individual and how dark your skies are.

If you are younger, ie. <40 and observe from "dark" skies the 35 Panoptic should work fine. If you observe from less than perfect skies, are older (ie, over 40), drink a lot of pyss, smoke a lot of cigarettes or ingest a lot of chemicals, it is likely you will have less than 7mm pupil dilation and the 27mm Panoptic would be a far better choice, because of the darker sky background it would provide. When I refer to "dark" skies I am talking about objects like M4 and M22 visible as naked eye targets, not 50km out of Melbourne, which some people refer to as dark. In any case the 27mm Panoptic would be a far safer option for that scope and perfectly suited under all sky conditions and for all observers, not just some.

Cheers,
John B

[Sarge (Rod)]

Thanks Jason, Thanks John,

That's pretty much what my research has shown. I think I'll go for the 27mm. As you say John, it's the safer option.

Ta

Rod