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Re: [APML] sharp image with 5 mm lense



Title:
Oh, and what happens if i go over 225x (theoretically?) ?
blurry images? other things? and what is the negative effect that one does not want that is most present when going over the
20x (or 40-50x) the aperturesize in inches?


Bert Katzung wrote:
Hi Mango:
All of the things you mention can contribute to a fuzzy image, but probably
the most important is the focal length of your eyepiece. Unless you have
superb optics (both eyepeice and mirror), a 5 mm eyepiece is pushing the
magnification too high in this scope. Your 1000 mm focal length with a 5 mm
EP gives 200x and that's asking a lot! A reasonable rule of thumb is 20x per
inch of aperture, so with your 114 mm aperture, about 80-90 x is the maximum
magnification you should expect to give nice clear images. I know that the
books claim a maximum of 40 to 50x per inch of aperture, but that's assuming
perfect optics and perfect seeing conditions.
Hope this helps,
Bert

Bert Katzung
katzung1@comcast.net
www.astronomy-images.com

----- Original Message ----- 
From: "mango" <j.kolling@chello.nl>
To: <astro-photo@seds.org>; <videoastro@yahoogroups.com>
Sent: Monday, November 10, 2003 9:11 PM
Subject: [APML] sharp image with 5 mm lense


  
I have a new telescope, a newtonian 114/1000
and when i used it to watch the moon yesterday
when i put in a 5 mm lense the image wasn't clear,
could this be because of the quality of the 5 mm lense,
the weather (it was not very clear and a little misty, but just a
little), the mirrorsize, the focal length, or something else?






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