Discussion on Wide View Eyepieces

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elton
Posts: 255
Joined: Mon Oct 06, 2003 10:42 am

Post by elton »

Weixing,

I don't think your analysis is correct. The full aperture of the scope is collecting light but that light is not divided over the TFOV. Think of it this way : the full aperture of the scope is collecting light for each point within the TFOV. Each point in an image is made up of its own set of light rays hence there is no sharing and dividing up of light. More than one non-parallel light ray can pass through each point on the scope's aperture. Hence, at the same magnification, the wide and narrow FOV eps will give the same exit pupil --- same brightness. Light is wasted when the exit pupil>your eye's pupil size. Normally when obbing in Singapore, ambient light will limit our exit pupil. I think 5mm is reasonable as the max exit pupil we can regularly achieve.
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denebman
Posts: 461
Joined: Mon Oct 11, 2004 4:40 pm
Location: Clementi

Post by denebman »

Hi, Weixing,

I think my answer for your Q1 and Q2 is:

"both will be the same"

liu ming
10" Telekit with Zambuto optics~TMB 152/1200 (construction)~Takashi Mewlon 210~TMB 80/600
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weixing
Super Moderator
Posts: 4708
Joined: Wed Oct 01, 2003 12:22 am
Favourite scope: Vixen R200SS & Celestron 6" F5 Achro Refractor
Location: (Tampines) Earth of Solar System in Orion Arm of Milky Way Galaxy in Local Group Galaxies Cluster

Post by weixing »

Hi,
Oh... :idea: :idea: :idea: Understand now... got the concept mess up while reading some article on how eye and eyepiece work... and my mind got metal block and can't think straight... :oops: :oops: :oops:

Thanks guys. :P :P :P

Have a nice day.

PS: The more I read, the more confuse I get... :? :? :? Conclusion, better don't read too much... ha ha ha :P :P :P
Yang Weixing
:mrgreen: "The universe is composed mainly of hydrogen and ignorance." :mrgreen:
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Canopus Lim
Posts: 1144
Joined: Fri Jun 03, 2005 12:46 pm
Location: Macpherson

Post by Canopus Lim »

I have a book called "Telescope Optics: A comprehensive manual for amateur astronomers" by Rutten and Van Venrooig. It is a very good book and talks about all the types of telescopes, its aberrations and eyepiece design. It will explain how the eyepieces actually work and how it was designed. Eyepieces are designed differently then the normal achromat/ apochromat objectives. I feel it is much more complicated than an objective alone.
AstroDuck
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