| View previous topic :: View next topic |
| Author |
Message |
Les
Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI
|
 Posted: Thu May 08, 2003 3:42 am Post subject: |
 |
|
| Bahgdad. |
|
| Back to top |
|
 |
45PSS
Joined: 28 Sep 2001
Posts: 4081
Location: Mid Peninsula, Ca.
|
| Posted: Thu May 08, 2003 6:36 am Post subject: |
|
|
and Bahdgdad gets its supply from the CIA.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU. |
|
| Back to top |
|
|
Dan Fromm
Joined: 14 May 2001
Posts: 2144
Location: New Jersey
|
| Posted: Fri May 09, 2003 12:33 am Post subject: |
|
|
| Quote: |
On 2003-05-07 20:11, RichS wrote:
Dan: Is there a simple equation you use to find out the vignetting in such a case? I know I could get out the graph paper and old geometry books, but asking is a whole lot easier 
|
Rich, I usually just draw a picture.
|
X______________|_____|
N A B
X marks the position of the lens' rear node.
The single pipe marks the position of the front standard.
The double pipe marks the position of the film plane.
Call the radius of the hole in the front standard r. The radius of the circle covered at the film plane is r* distance N-B/distance N-A. And there you are.
Long lens, short bellows, small front standard make for a small circle at the film plane.
As I said, similar triangles. Doesn't take graph paper, a scale model isn't required. You just have to get the idea.
Cheers,
Dan
|
|
| Back to top |
|
|
RichS
Joined: 18 Oct 2001
Posts: 1468
Location: South of Rochester, NY
|
| Posted: Fri May 09, 2003 3:17 am Post subject: |
|
|
Thanks Dan! Another one I'll have to save and try to remember where I put when I need it. And I'll have to run a few numbers through it to see what kind of lens I can hang in front of a 4x5.
But for now, I'm off to Baghdad 
|
|
| Back to top |
|
|
Dan Fromm
Joined: 14 May 2001
Posts: 2144
Location: New Jersey
|
| Posted: Fri May 09, 2003 11:22 am Post subject: |
|
|
| Quote: |
On 2003-05-08 20:17, RichS wrote:
Thanks Dan! Another one I'll have to save and try to remember where I put when I need it. And I'll have to run a few numbers through it to see what kind of lens I can hang in front of a 4x5.
But for now, I'm off to Baghdad
|
Going to eBay costs less and is less hazardous. |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
