Click here if you are having trouble logging into the forums
Privacy Policy |
Please read our Terms
of Service | Signup and
Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User
David E
Carpal Tunnel
Reged: 05/25/06
Posts: 1922
Loc: North Carolina
|
Re: Binoviewer Noob- Please help put me out of misery!
05/19/08 09:11 AM
|
|
|
Vignetting is when something reduces your field of view before it reaches the eyepiece. For example the baffles may be too large, or the focuser tube too long. The best way I know to describe it is to look through an empty cardboard tube. The opening at the far end is smaller than the opening at your eye. If you buy a premium brand like Denkmeier or Televue, they have clear apertures big enough that you don't have to worry about vignetting. They have clear apertures around 26 or 27mm. The import (~$200) binoviewers have a clear aperture around 20 or 21mm. If you happen to have both a 32mm and 25mm plossl (any brand) you can turn them upside down and look through them and see how the aperture (called the field stop diameter) is much large in the 32mm. If you measure it with calipers, the 32 will be about 27mm wide and the 25 will be about 21mm wide. So you can see the 32mm will be wider than the 21mm of the import brands, causing vignetting. Now, with the imports, it's not really a bad thing, you just have to know that you won't see as large a field of view with a 32mm plossl through these binos as you will looking through one eyepiece in "mono" mode. But as I mentioned, since you want the Denk Big Easy, you won't have to worry about this issue with any 1.25" eyepiece.
David E
--------------------
David E
So when at times the mob is swayed
To carry praise or blame too far,
We may choose something like a star
To stay our minds on and be staid.
-Robert Frost
|
|
0 registered and 2 anonymous users are browsing this forum.
Moderator: EdZ, jrcrilly
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Rating:
Thread views: 1454
|
|
|
|
|
|
|
Previous
Index
Next
Flat
Edit
Reply
Quote
