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Re: Why Longer Focal Length for Planetary?

Subject: Re: Why Longer Focal Length for Planetary?
From: "CLT"
Date: Thu, 14 Jul 2005 20:41:28 -0700
Newsgroups: sci.astro.amateur
Assuming all else remains the same, correction will be better in a longer
focal length. Additionally, you are looking at tiny objects that call for
higher magnification. With a longer FL scope, you can use longer FL
eyepieces, with better eye relief. It also works out better for photos,
again because of the small size needing magnification. Additionally, the
steeper light cone of a fast scope is more demanding on eyepieces. A longer
focal length allows you to use simpler eyepieces.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try http://groups.yahoo.com/group/lunar-observing/

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"Mij Adyaw" <mijadyaw@xxxxxxxxxx> wrote in message
news:x8FBe.31449$8o.1177@xxxxxxxxxxxxx
> Why do many serious planetary observers choose longer focal length APO
> refractors over shorter length APO refractors for planetary observation?
> Assuming a very well corrected APO like an AP or a TMB, what is to be
gained
> by the longer focal length assuming that you have a full compliment of
> excellent eye pieces in all available focal lengths?
>
> -mij
>
>



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