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.
I think I'll try this on a film camera over the next few days and see what
happens.
...Wayne
>
> More playing with the E-300 + Tamron 90/2.5.
>
> When the Tamron is stopped down to f22 and I take a shot of a
> blank wall I get something like this:
>
> http://lrh.structuregraphs.com/images/e-300-tamron-1.jpg
>
> Notice the bright spot roughly in the middle of the frame !
>
> This behaviour starts to become noticeable at around f11.
>
> The problem doesn't occur with the 14-45mm or the Zuiko 85/2 !
>
> I have heard of flare problems (Nikon context from memory)
> with light bouncing off the sensor to the rear element of a
> lens and back again. Could the geometry of the Tamron be
> just right to show this effect ?
>
> ...Wayne
>
>
>
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