Adjustable eye cup question.

[MilwaukeeLion]

Luminos 15mm / 82 deg.  Dumb question perhaps but adjuster ring to raise or lower eye cup, is purpose to just block reflections or also fine focus?  My good eye is not great but this morning viewing prom with pst seemed focus changed a bit from highest position to lowest.  Thanks!

[John]

It does not change the position of the optics so focus should not be affected. It does change the position of the eye in relation to the top lens of the eyepiece. The purpose is to allow different people to find a position where they can see the exit pupil of the eyepiece easily. People who wear glasses when observing usually find that having the eyecup in the lower position works best whereas those who don't wear glasses often find a higher position works for them.

 

[MilwaukeeLion]

2 minutes ago, John said:

It does not change the position of the optics so focus should not be affected. It does change the position of the eye in relation to the top lens of the eyepiece. The purpose is to allow different people to find a position where they can see the exit pupil of the eyepiece easily. People who wear glasses when observing usually find that having the eyecup in the lower position works best whereas those who don't wear glasses often find a higher position works for them.

 

Thanks, did not know that.  Always take glasses off, will try with glasses on if sun pops back out.

[RT65CB-SWL]

If you have a TeleVue Radian* and/or Nagler-T4** they included is this plastic disc --->

This disc is what they called a 'Pupil Guide'... (I have attached the instructions on how to use it and for the eyepiece). You can use the  e/p's with or without it. Basically it is to help you position your pupil, as the adjustable eye-guard is moved up or down the barrel. It does not help with focusing; but does help in masking stray light on the external glass surface or reducing internal glare resulting in better contrast, etc.

  * 60deg AFOV
** 82deg AFOV  

TV Pupil Guide Instructions.pdf TV Radian Eyepiece Instructions.pdf