Hi Miha,

I'm jumping late in this one... ;-)


> So I think we've solved my puzzle. Now I know for sure (not just from
>   theory) that my underxposed slides are due to the nature of Evaluative
>   metering. As someone noted.
>

The problem is not the extension tube nor the evaluative metering  but the
nature of the shot you're doing. You're using extension tubes to get closer to
your subject, right? Then your subject is filling the frame or almost, right?
Then, what you're doing is using a big matrix meter for the same you would use a
spot meter if you were a tad further away from your subject... and we all know
that when you use a spot meter, you should compensate for the subject tonality.
++ for light subjects, -- for dark ones. Bracket when you're not sure
(sometimes, even if you are ;-)  ;-) .

I used once extension tubes to shorten the focus of the 75-300IS to photograph
some ducklings. I could fill the frame from about 1mtr ( the closest mother duck
would allow me to get,  (min focus distance of the 75-300IS all alone is 1.5m) )
and I used evaluative metering with good results (it's a pitty I don't have them
scanned... :-(


> Did not cover the viewfinder.
>

As Julian pointed out, I think here is the clue. When light enters from the
viewfinder, the meter tends to show the highest value between this intrusive
light and the light coming from the lens (thanks Canon it doesn't "ADD" them!).
The pretty uniform exposure values you're getting could have been because the
meter was giving you the reading of the lamp behind you and not the subject
itself.  It's always a very good idea to cover the viewfinder. My favorite
method is using the cap of the 28-135IS, since it 'clips' on the rubber borders
of the eyepiece.  Removing the eyepiece to fit the plastic cover provided on the
strap is only calling for trouble. The clips of the eyepiece are very fragile.

Have fun with your macro shots!!

(I'm just playing inversing the 28-135IS... a zoom macro lens with IS: can it
get any beter?... well, I'll have to do some shoting to answer myself, since it
was just few hours ago since I picked up some step-down rings to screw the lens
on the adaptor that bridges  the EF connection )

Regards,

Gerard.

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