I want a 90mm lens for my Cambo Legend setup. Vingetting?

I fear it because I can't afford to spend $500 on a center filter for the

camera.

 

Which 90mm lenses will show the least vignetting for shooting at f/22?

 

What kind of DOF should I expect from a 90mm lens on 4x5? Would f/22 be

excessively small or about right?

 

thanks

I have a MC 90 Super Angulon and have shifted 1.5 or more inches into the long side of 4x5 without a problem using f22.

Modern LF wide-angles use an optical technique to improve off-axis illumination. These

method is used by the Super-Angulons (but not the plain Angulons), Grandagons, Nikkor-

SWs, and Fuji-SWs. Any of these will give you improved off-axis illumination compared to

older designs. Very few 4x5 photographers find a center filter necessary for a 90 mm.

 

Typical apertures are probably f16 to f32, but it depends on the subject distances and

what you want to accomplish.

 

Here are two past discussions:

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00FhGt and

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=005gK2

A theoretically perfect 90mm for 4x5 will have a loss of more than

1.5 f stops in the corners. This is called the cosine of the fourth failure and it is physics, not optical design!

 

The shorter focal lengths are even worse, but that failure frequently improves the look of the photograph. Even if you enlarge full frame, the corner losses will largely balance the cosine failure due to edge reduction in these instruments.

 

Lynn

If Mr. Lynn Jones speaks, listen. If he is the same LJ, he helped worked for Calumet/Caltar designing among other things, wide angle large format cameras.

Optical designs exist that have improved

illumination than cosine to the fourth, including the lenses that I listed in my first answer.

Cosine to the fourth is theoretically perfect under certain assumptions. If the lens designer

violates those assumptions, they can do better. This is explained in one of the past

discussions that I linked. Datasheets available on the web from Rodenstock and Schneider

for Grandagon-N and Super-Angulon lenses show off-axis illumination that approximates

cosine to the third, which is better than cosine to the fourth.

Light drop-off is inevitable and as noted gets worse the wider the lens perspective, but its impact is also in part relative to the film and the amount of camera movement used (keepin in mind that your worst problems will ALWAYS be at infinity focus). Low contrast film and little camera movement will reduce your risks, and of course using a polarizer may well destroy the image if great care is not used.

 

It's always nice to avoid using a center filter, but if you are using Velvia or other contrasty film, and worse yet with a polarizer, you may find a filter greatly improves the final image. Or not.... :-)

Hi Steve,

 

Yes you found me, feel free to email me. lynn@austincc.edu

 

Lynn