Re: Horseman SW 612 & also 47mmXL

[Willem-Jan Markerink <w.j.markerink@xxxxx>]

On 23 Jun 99 at 18:29, Joel Seaman wrote:

> Mitch,
> 
> The 6X12 Horseman back produces a nomial image size of 56 X 112MM.  The Rodenstock
> catalogue does show an image cirlce of 131mm, but when the cirlce is drawn over a
> rectangle 56X112MM one does see overlap, as they illustrate in their catalogue.
> Yet they claim that with a 6X12 back (56X117MM) one should still have 4MM vertical
> and 2MM horizontal adjustment!  

56x112mm means a diagonal of 125mm (SQR (56^2 + 112^2)), so you have
roughly 3mm play in each direction.
I believe both 35mm and 45mm have an image circle of 
131mm....however, it all depends on HOW this image circle is 
established....it varies with focus (infinity is worst, close up 
inherently better) and aperture....and it also requires a method of 
qualifying the 'edge', as not all lenses drop dead within a single 
millimeter....I believe especially older lenses show a very gradual 
fall-off.

> Now the shift doesn't interest me as I don't have
> that feature on my camera, but I don't understand the claim (since I don't have an
> education in this area).  

Don't forget that with the 35mm and the 6x9 back, you have a very 
interesting super wide angle constellation, and in that case, all 
the shift you need. That in fact would be my only reason to prefer 
the shift version....and the Horseman brochure doesn't hide the fact 
that you can't use shift on either 35mm or 45mm in case of the 6x12 
back....
Btw, I also heard rumours about a 135mm lens....
 

--                 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]