Hello Kent,
> your advise is very helpful but can you tell me how to adjust your
> tamron mount?
ONLY if the maximum aperture is not shown correctly in the viewfinder of
your Aria you have to adjust the lever which I've marked in the image.
> From your above-mentioned, it means that the floating aperture would
affect
> the result (as the camera indicated the largest aperture was f3.5 when
> the CZ len at the 85mm focal lenght and actually it should be f4).
The changing aperture of a zoom lens isn't recognized in the viewfinder
display. The Contax mount doesn't support such function. Your
Vario-Sonnor is loosing half an f-stop if zoomed. So you should see the following: the maximum aperture should be shown as 3.5 in the viewfinder and does not change while zooming. The exposure time should change from, lets say, 1/125 sec to 1/90 sec.
But there is another problem. The viwefinder and the engraving on the
lens show f-stops. F-stops are calculated by the diameter of the
aperture divided by the focal length (you can simply measure and
calculate this!). But a lens like the Vario Sonnar with 16 lenses in it
has got some more light loss. Correctly the t-stop must be shown where
this light loss is regarded.
> According to the aforesaid, the exposure time maybe be all under 0.5 -
> 1 steps when using the hand held light meter.
As I already said in my last Mail. It is quite difficult to compare a
handheld meter to a build-in camera meter 'cause of the different
measuring angles. My Gossen Lunasix 3 has got an measuring angle of
about 30°. The angle of the camera depends on the focal lenght of the
lens. If you don't measure an absolutly homogeneous area, you'll get
different readings. And then comes the before written about the t-stops
in account...
Take a sharp look to your slides. If they're quite good exposed with
each of your lenses I won't make me headaches about the readings!
Matthias