So does anyone else not even think about exit pupil? In my world, it isnt even a consideration. I am so seeing limited that getting to the perfect exit pupil for my scope just doesn’t happen all that often. What i worry about is magnification or eyepiece choice. Far and away i spend most of my nights using a 13 or 21mm eyepiece in my 16 inch which is 140 or 90x. That is all the math I really need to know. Anything else is just more math that isnt really necessary
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I have exclusive eyepiece sets for each of my scopes . On the barrel cases I have the focal length of the eyepieces and the magnification of what that eyepiece will yield in that particular scope . Then I made up a laminated card that gives the eye relief and exit pupil of each eyepiece in the set for that particular scope . Not that it’s a big deal but it’s kinda nice to have that pre calculated information at hand . The only time I’ve ever had a problem with exit pupil is with my 32mm Plossl in my 8” f4 Schmidt Newt which IIRC is at 7mm . If my eyes aren’t fully dilated due to starting to view earlier than full darkness , the shadow of the secondary mirror is on full display . Once my eyes are fully dilated , that phenomenon disappears .
@Starrancher i have everything written down on one sheet of paper. Sounds like it is the same info you have except i add a mag limit. The only eyepiece i have, well that i notice a secondary blackout on, is the 56mm and it is exclusively used on my SCT
So when you see that , the exit pupil of the eyepiece is larger than your eyes pupil .
With a SCT I’m assuming it’s f10 . What magnification is that yielding in your scope ?
@Starrancher . First i am one of the lucky people who’s pupil gets really big. The last time i was at the eye doctor I had him measure them. I am just shy of 8mm at normal dark adaptation. So i can use about any eyepiece i want and be good to go, the only exception i notice is the 56mm, i only notice it during the day. At night it is gone. The SCT is F10 and while it can go to 500x I rarely take it past 200x because my skies generally suck. I spend a lot of nights between 80 and 140x
So what magnification are you at using the 56mm in the SCT ?
@Starrancher it only gets me 45x. Its my low power and go wide eyepiece in my SCT
I use a 26mm Plossl in my 8” f4 Schmidt Newt and get 31x . Under a dark desert sky I get the entire Andromeda galaxy in the 52 degree apparent FOV . The far reaching faint edges might spill over ever so slightly . With a 32mm Plossl I can get down to 25x but the exit pupil exceeds my dark adapted eyes some .
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@Starrancher yeah i guess I am one of the lucky people that have freaky large pupils at night. It does explain my exceptionally good night vision in general
Right . If you can get to 6mm you’re doing pretty good . Last I checked I could get there but last I checked was 15 years ago .
@Starrancher i have mine checked every year or two when i have my eye doctors appointment. Last November he measured me at a strong 7mm, bot quite 8mm. So i am doing good
Is that with the drops they put in your eyes to dilate them ?
@Starrancher no chemical additives required. That is my normal dark adaptation without any assistance.
Now that’s pretty amazing .
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@Starrancher i have had it measured every year for the last three years. Just hangs between 7 and 8mm.
8mm is like the maximum with young healthy eyes . At my age I might still be able to get there . Even if not , the only problem I would have is a couple long focal length eyepieces in my short focal length scope and at powers down in the Sub 30x magnification range . At that point it’s time for binoculars . But what do you get other than being able to fit M45 into the FOV . That and maybe a few other open clusters is about all I’d use binoculars for in the celestial realm .
@Starrancher i don’t really get that eyepiece out unless i have to. When the SCT is up i usually also have something else out that goes wider