avoiding vignetting by checking the corners

Hi

an old 'trick' I use with my LF camera is to check on the corners of the ground glass (through the gaps) to see if the lens is shaped nicely or if I've gone and moved it too far. Naturally one needs to stop down to the taking aperture for this.

I was just fiddling around with a newly purchased Bessa I and found that when viewing the corners that I needed to stop down to f16 or so to prevent me seeing what I would think of as vignetting happening.

Is this technique valid in this format (can't see why not?) and does this mean that these cameras vignet at f11 and wider?

Thanks

This technique is valid with any format. If using a short lens, or if this is an original roll film Bessa it may very well vignette at larger apertures. The 45mm does so on the XPan - and is so noted in the owners manual.

I have used looking through the clipped corners on my 4x5 to do exact taping off of the lens shade. You would be surprised what a difference that makes with back lighting or white backgrounds. I looked though the back of my Rolleiflex recently to see how exact is the square lens shade I opened the lens in B and stopped down one stop and found that it is exactly to the edge at closest focus. Which of course means that at infinite it is a bit too large.

folks

thanks for the verification. The Bessa I is a 6x9 120 roll film beastie (Vaskar 105mm f4.5)

Its something that most young folk out there (I'm young) don't seem to know, and of course you can't even do it with a digital ;-)