Nagler T6 question

[sixela]

I think that those blackout areas that appear on the field of view due to your eye positioning can be considered a fault.

Spherical aberration of the exit pupil can be thought of as a fault, because no matter where you place your eye you can't have good illumination in the entire field if it's bad. But that affects T1 Naglers, not T6 Naglers.

Blackouts due to looking around in the field, though, are not a fault. They're inherent in the geometry of the problem: you can only have the exit pupil at one place, and you rotate your eyes around the middle of the eyeball and not your eye lens. If you look somewhere else you move the eye lens relative to the exit pupil unless you instinctively compensate with head movement or rotation.

Meanwhile, that doens't seem to be related only to the wide fields because the Epics I mentioned are only 55º

I didn't say it was impossible to design an uncomfortable 55° eyepiece with spherical abberation of the exit pupil (it certainly is).

I said it was impossible to avoid seeing at least some newer users of 82° eyepieces experience blackouts when they were looking around, even with perfect eyepieces.

and the Ethos are 100º and people don't complain about black outs...

Neither do I, and I also don't complain about them when using T6 Naglers. The Ethos doesn't exactly have the same audience; many people who buy them have a had wide field eyepieces before and have learned to cope with them.

But give me a star party and many people will complain about blackouts too in my Ethos once they start looking around. Even though I personally find pupil placement slightly easier than on T6s (because of the concave eye lens and the slightly higher eye guard on the Ethos).

Let's not forget that the point of the thread is not to complain the T6 fails to violate the laws of physics even though it's expensive. It's to answer the original poster's questions:

Do other forum members have any similar experience of this eyepiece or are blackouts with certain eyepieces very much an individual phenomenon? Perhaps viewing comfort will come with more experience in finding the correct eye position?

All I wanted is to provide context for the answers:

-Yes, I've seen others have similar experiences with T6s, not getting the hang of it immediately (and it even took me a couple of nights to get used to the T6, because the eye guard ,which is slightly too short for my face, makes it easy for me to place the eye slightly too close.)

-Yes, blackouts (at least the type due to looking around in the field) are very much an individual phenomenon.

-Yes, a long experience with 82° eyepieces improves the comfort in using all of them, because learning to keep your eye lens in one place while you rotate your eye is a skill you need in all of them.

The only "uncomfortable" 82° eyepiece for me is the UWAN, but that's probably because of the way I have to put my head to avoid the large eye dish. It interferes with the instinctive way I developed of using the other 82° eyepieces.

[West End Wendy]

Thanks again for all your replies. I'm much clearer about the whole issue now.

As someone said in another thread - you learn more about practical astronomy from this forum than any book.

Tim

[spaceboy]

Thanks again for all your replies. I'm much clearer about the whole issue now.

As someone said in another thread - you learn more about practical astronomy from this forum than any book.

Tim

Ditto

[Ags]

Another question... Is the blackout situation affected by dark adaptation? The problem is aligning the eye with a very broad light cone, so surely a pupil which is not yet fully dilated would make the task even more difficult?

[sixela]

Yes, but pupils dilate to (almost) their full size fairly rapidly, at least at night. In daylight, it's indeed usually blackout fiesta.

It does affect you at night when you look at very bright objects and especially the moon, of course.

[spaceboy]

I have been playing with me EP's today trying to work out how to move my head instead of my eye and it dose actually work. Just wish I could try it out at night on the sky. DAM you low atmospheric pressure!!!