Coverage of 300mm Symmar Convertible

Does anyone have any data on the coverage of the 300/500mm Schneider

Symmar convertible lens. I was testing the lens on 11x14 and I was

surprised to see that it covered the format. I was shooting at f22

with the lens focused at infinity and there did not appear to be any

significant light fall-off at the corners of my final print. Some

foreground elements were somewhat out of focus, but this may be a

function of the camera set-up and the fact that I did not use any lens

tilt. I knew the lens covered 8x10 and I had used it with success on

studio images at large magnification ratios (3:1, 2:1, etc.). I

normally use a 480mm Red Dot Artar for 11x14 but I was looking for a

wider angle. Is it possible that the Convertible Symmar covers 11x14

with little or no movements? Or am I just not seeing the limits of the

image circle. Thanks for your help.

<p>

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Check www.schneideroptics.com (knowledge : vintage lens data : large

format lenses : symmar).

Stephan:

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I looked at the Schneider site before but I only found a reference to

the the 300mm Symmar. According to the data chart, the lens covers

402mm at f22 focused on infinity. This would cover 8x10 but seems to

fall short of the 452mm I assumed for 11x14. This leaves me with two

questions: (1) Is the coverage of the 300mm Symmar the same as the

300/500 Symmar convertible? and (2) Does the 300/500 perform beyond

the limits of its indicted coverage? I recall reading that some

manufacturers provide conservative data with respect to coverage. It

also seems possible that with some lenses there might be two areas of

coverage. The first area would be an area of criticl focus where the

lens does not exhibit softness or light fall-off. The second area

would be characterized by increasing light fall-off, etc but may not

show the full limits of the lens, especially in a contact print.

Having said that, I also recall reading that this type of description

might apply differently to older and modern lenses.

<p>

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Schneider is fairly conservative with image circle specs, and it seems

that you have discovered that this lens can cover a larger format than

stated. At the 500mm focal length, you won't see much change in image

circle size.

Dave,

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The Symmar 300mm is the 300/500mm convertible. Apparently, most, if

not all lenses named Symmar are convertible (I now the 150, 180,

210 ,240, 300 and 360mm are). Schneider later recalculated these

lenses so they were no longer convertible, to give better performance

(the Symmar-S series).