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
Lawrence Sayre
Abbe Normal
Reged: 10/16/04
Posts: 4912
Loc: N.E. Ohio
|
Re: Strange Results in Eyepiece FOV Comparisons
05/17/08 07:03 AM
|
|
|
Actually the RFOV of the 13 mm Ethos can be calculated, since TeleVue gives us the field stop as being 22.3 mm.
RFOV = FS/Eyepiece_FL * 180/Pi
RFOV = 22.3/13 * 57.296
RFOV = 98.28 degrees
This tremendous result would indicate that pincushion distortion (rectilinear distortion, or the bending of straight lines) is quite well controlled for the Ethos, and this means that by default it must have predominantly angular magnification distortion instead (whereby objects do not retain a common magnification [size] across the field if view). With a field that wide, one would likely never notice that Saturn for example is perhaps 5% or 6% different in size from center to edge, and since stars effectively do not change in size (having no effective size to magnify by virtue of being "point sources"), this effect would never be noticed for them.
--------------------
My philosophy, in essence, is the concept of man as a moral being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute.
Ayn Rand (in the appendix to 'Atlas Shrugged')
|
|
25 registered and 10 anonymous users are browsing this forum.
Moderator: Greg K., Jason B, csa/montana
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Rating:
Thread views: 1873
|
|
|
|
|
|
|
Previous
Index
Next
Flat
Edit
Reply
Quote
