Archived posting to the Leica Users Group, 1997/11/07

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: 35mm/2 light falloff question
From: Bob Parsons <>
Date: Fri, 7 Nov 1997 20:58:04 +0000

Mike Gardner wrote:
> rardinge@KUHUB.CC.UKANS.EDU wrote:
>> Aquestion about light falloff,
>> I noticed a different (than expected) result last night when looking at
>> some new proof sheets.  I have a new to me, actually  "preowned", 35mm/2
>> summicron (#35x,xxx , non asp., has notches for lens hood) that I am quite
>> happy with but on the last set of proofs there are several frames with
>> noticable corner vingnetting.
>> Robert,
>  Take that filter off and your problem will disappear.  Been there, done
>  that.  The bigger your aperture the more pronounced the vignetting.

A very quick way to find out if the rim of the filter or lens hood is
causing vignetting is to do what the large format guys do. Open the camera
back, set the lens at full aperture and open the shutter. With a white card
a few feet from the front (or use the sky) look through the lens from the
back of the camera.

Now twist the camera or move your head until the bright area of the lens
aperture is in one corner of the frame. If the area goes dark before it gets
to the corner then you have mechanical vignetting. As a check you can put a
finger just over the edge of the lens hood or filter rim to identify this

Using this method I've found that most Leitz/Leica hoods just, but only
just, start to vignette showing the design is optimum.

Bob Parsons.