Olympus-OM
[Top] [All Lists]

Re: [OM] Zooms at Dawn - the 50mm shootout - Teaser

Subject: Re: [OM] Zooms at Dawn - the 50mm shootout - Teaser
From: Moose <olymoose@xxxxxxxxx>
Date: Tue, 20 Apr 2010 21:33:17 -0700
On 4/20/2010 4:28 PM, usher99@xxxxxxx wrote:
> ...
>
> Moose's  comment about the relationship between MFD, FL and mag at 1:1 is 
> quite cool--never seen it expressed that way---clearly is correct and a 
> really neat thing to know.  Thanks!!
>    

I thought everybody knew that. ;-)

> Closest I got to the algebra to prove it is 2F=G at 1:1 but g is only the 
> distance form lens to subject and doesn't include MFD from focus plane to 
> subject.

1/S1 + 1/S2 = 1/f  - The thin lens formula
M = 1 = S1/S2      - The magnification formula applied to 1:1
.: S1 = S2
2/S1 = 1/f
S1 = 2f
S1 + S2 = 4f


> Too tired to  try right now, it is clearly correct.  Must measure with Big 
> Foot at 1:1 as it uses a combo of standard extension and floating 
> elements--down side of straight extension is loss of light of course.
>    

I agree with Wayne. It doesn't matter how the magnification is achieved, 
the inverse square law applies.

Moose
-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz