From: "Jan van Gastel" 
To: "Jack Schmidling" , "ATM"

Reply-To: "Jan van Gastel" 


Jack,

The smallest diagonal for this scope would be about 42 millimeters. The
fully illuminated field is then 1.5 millimeters and the edge illumination a
bit more then 70%, given a 2 inch eyepiece with an apparent field of 68
degrees.
For the 46 millimeter diagonal I find a fully illuminated field of about 8
millimeters (not 12) and an edge illumination of 80%. The total field (in
both cases) has 16 mm radius.

Jan
http://home.wanadoo.nl/jhm.vangastel/Astronomy/


----- Original Message -----
From: "Jack Schmidling" 
To: 
Sent: Tuesday, June 17, 2003 5:16 PM Subject: ATM Diagonal Help


>
> I would appreciate it if someone would go over my numbers for the diagonal
> in my 4.25" astrograph.
>
> I do this by laying out a scaled drawing and measuring what I come up with
> but it would be nice if someone could crunch the numbers in one of the
> equations that I don't understand for a second opinion.
>
> Here are the numbers in mm's:
>
> Aperture................................................106
> Focal Length..........................................413
> Focal Plane to center of tube................. 160
> Fully Illuninated Field (diameter).............  12
>
> I came up with............  Diagonal Minor Axis =  46
>
> Actually, that was a bit too big but a readily avaiable size.
>
> How did I do?
>
>
>
> PHOTO OF THE WEEK http://schmidling.netfirms.com/weekly.htm
> HOME: Astronomy, Beer, Cheese, Sausage, Videos
> http://schmidling.netfirms.com
>
>
>
>
>

--- BBBS/NT v4.01 Flag-4