|
|
|||||
|
Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place... The Space and Astronomy Agora |
Re: Negative Focal Length
Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To Posted by stevec/">stevec on February 23, 2000 07:34:09 UTC |
: How can the focal length of a negative lens be found without buying an expensive curvature measuring instrument? You can make a simple spherometer with a dial indicator,some ball bearings and aluminum plate for less than $25 i have made cassegrain secondarys and determined the negative fl by finding the fl of the concave tool used to grind the convex secondary, a good book which describes how to make several different spherometers is advanced telescope making techniques,volume 2. good luck. |
|
Additional Information |
---|
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy |
Unless otherwise specified, web site content Copyright 1994-2024 John Huggins All Rights Reserved Forum posts are Copyright their authors as specified in the heading above the post. "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" are trademarks of John Huggins |