Wayne wrote
> Just finished a short series of tests (now that's something digital IS
> useful for !) with the Tamron 90/2.5 on the E-300. Set the camera up on a
> tripod about .6m from a blank wall and changed the focus of the Tamron from
> 0.4m
> to infinity. The resulting images (just resized) are here:
>
http://lrh.structuregraphs.com/test/tamron_90_re_reflect.htm
>
> Obviously the rear element of the Tamron (which is concave facing the
> sensor) reflects a nice spot of light from the sensor back to the sensor.
> As the Tamron is focussed closer (rear element further from the sensor) the
> spot
> is less well defined.
Well, that is a very interesting piece of information. And by the way, did you
notice the colour separation at 10 and 4 oclock around the spot?
Some of you might remember I bought a Tokina ATX 24-40 f/2.8 from KEH a
couple of years ago, with the much appreciated help of Mr NSURIT to get
around the KEH practice of sending everything out by courier (VERY
expensive over seas).
This lens is heavy but sharp, which I why I bought it.
AND, in situations where I least expected it, where I had taken special
measures to avoid flare, the images had a *large* (10 - 15% + of image
width) bright blue round spot with no hint of aperture blades, in the middle of
the shot.
The different distance of the view-finder from that of the film must somehow
explain why it did not show in the view-finder.
I wonder how to avoid it?
Brian
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