Re: Maximum Extension Tube Length

[Shel Belinkoff]

"Robert P. VanNatta" wrote:

> the classic 50 mm f1.7 reversed with 
> 3 extension tubes is said to provide
> a 1.54 magnification and required an 
> exposure compensation of 6.2 f stops.
> 
> A 28 mm f2.8 reversed with 3 extension 
> tubes is said to provide 3.78 magnification
> and require an astounding 19.1 f stops of 
> exposure compensation.

Where did you get that information?  Is there a formula for
calculating these results?  You mentioned a book in one of
your earlier posts - what book is that? Thanks! 

-- 
Shel Belinkoff
mailto:[EMAIL PROTECTED]
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