Re: ATM 8" Achromat

["Kreig McBride" <kmcbride@memes.com>]

Dave,

First you might try and look at the edges of the lens. Most Opticians
usually write information such as f/#, focal length, date, or other
important information on the edge. This can be accomplished without taking
the cell apart.

Once you have the instrument mounted up you will find just how nice it is to
have an adjustable cell. Getting the achromat dead on center will make a
noticeable difference in performance, especially on brighter objects.

Hope this helps.
Kreig McBride
Bellingham, Wa
www.wwu.edu/~skywise/optics.html

-----Original Message-----
From: David Simons <hmsimons@hotmail.com>
To: atm@shore.net <atm@shore.net>
Date: Tuesday, August 10, 1999 5:18 PM
Subject: Re: ATM 8" Achromat


>
>I finally received my R. E. Brandt 8" f? achromat objective lens. It has
>come in a very strange long cell that I can't tell which end is the front!!
>
>There is one side that appears to have push-pull alignment screws. I am
>guessing that is the front of the lens. This side appears to be convex
while
>the back side seems to be concave. Does this sound right?
>The spacing between the lenses is the thickness of a folded stamp.
>
>Also I need a way to verify the focal length of the lens, I have a ~1/2
wave
>mirror I was thinking of reflecting the light of the sun or moon using this
>mirror through the lens and then using a tape measure to verify the focal
>length. Does this sound reasonable? Or is there a simpler way to do this?
>
>My plan is to fold this design into something transportable. I haven't
>decided which optical path to use yet. I'm favoring a single mirror at the
>bottom to fold the FL in half.
>
>Dave Simons
>San Jose, CA
>
>
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