Agnus's blog/

I have now had some more opportunities to further test my manual focus lenses with M42 screw mount. Now that my autofocus-confirm adapter has arrived I moved from the focussing issue to the next problem: light metering and erronerous exposure aswell as milky pictures when shooting backlight photos.

The first part seems to be a known issue and apparently relates to an exposure compensation algorithm that EOS-bodies apply to compensate for non-linear light metering. Look here and here for further information. (Hier auf Deutsch.) My AF-confirm adapter emulates the presence of a 50 mm lens at aperture f/2.0. All lenses I tested seem to exposure correct when set to this aperture. The lower the aperture the higher the degree of overexposure (up to + 2 EV @ f/16) and that ssems to be true regardless of which lens I have screwed on. I tested this behaviour on the following lenses (M42-mount) on my EOS 400D:

• Carl Zeiss Jena Flektogon 35 mm f/2.8
• Helios-44M-4 58 mm f/2
• Hanimar 55 mm f/1.4
• Auto Revuenon 55 mm f/1.4
• Porst Tele MC auto D 135 mm f/2.8

It seems as if I have to live with the overexposure and as far as I am aware of the issue and shoot in RAW I can deal with it.

But last weekend another issue showed up: when shooting backlight photos all of the above lenses show not only flares (reflections of the aperture ring but the whole picture looks milky, misty, glaring, contrast-poor and whatever else you might want to call it. Further down you will find some samples.

I agree these pictures were shot without lens hood but I never before in my short photo-career have produced such pictures with one of my new Canon-, Sigma- or Tamron lenses and I didn't use lens hoods in the beginning. The horse was even shot with the built-in lens-hood extended!

Has this to do with coating? Has anyone made similar experiences and/or has an explanation for that behaviour?

backlight 3

backlight 2

backlight 1