Friends. I purchased a F8 fixed apeture 500MM mirror lens and am a little confused as to how to meter for exposure. I am using a Canon Elan 7 camera. Which mode should I use? Manual-time-or apeture? And Why? THanks

-- John Nagle (tjn318@erols.com), September 19, 2001

Answers

Mirror lenses do not have adjustable apertures. So you can't shoot in P mode or Tv (shutter priority) modes, since both of those modes rely on the camera's ability to alter the aperture of the lens.

So you have to shoot in M or Av modes in stop-down metering mode. For more info on stop-down metering have a look at my page on the original Canon Elan:

http://www.grocible.com/photo/elan-instructions.html

-- NK Guy (tela@tela.bc.ca), September 19, 2001.

Actually...this depends on the camera.

If the camera displays "00" as the aperture, then it is safe to use P and the camera will not attempt to change the aperture.

If the camera appears to be setting apertures as normal, switch to Av mode, and set the aperture to 1.0, and then it will not attempt to stop down the lens at all. Also works for manual mode.

-- Isaac Sibson (Isibson@hotmail.com), September 19, 2001.

Sorry - Isaac Sibson is right. Got myself confused between the old and new EOS behaviour - the Elan 7 obviously using the new behaviour.

Look at my Elan and 10s manuals on my Web site for the longer explanations.

-- NK Guy (tela@tela.bc.ca), September 19, 2001.

Just to clarify, the "new behaviour" is the aperture display of "00", which allows you to use P to shoot with fixed aperture lenses.

-- Isaac Sibson (isibson@hotmail.com), September 20, 2001.