Hello Nikon-digest (nikon-digest)!
(1 április 99) You wrote:
nd> I tried to take pictures from slides using ISO 100 negative film
nd> with my F90-X and AF-D 105 mm micro-Nikkor
nd> set at f /2.8 aperture and matrix metering exposure mode.
nd> I used a home-made apparatus with a well diffused light source.
nd> I got catastrophic results!
nd> I took 20 pictures. I got just 2 properly exposed!
nd> The others resulted in extreme overexposure.
nd> It seems I should set - 3.0 EV to get them properly exposed.
nd> The subjects in the pictures are not so dark nor so light. So, I didn’t
nd> use exposure compensation in any picture.
nd> Why did the sensors fail to calculate the correct exposure with
nd> transmitted light through the object? Has it to do with the contrast?
nd> When I take normal pictures (reflected light) the matrix metering
nd> works well, even at reproduction ratio 1:1.
1) Slides often have more contrast then real life (gamma > 1). The matrix meter
algorithm exp. more on contrasty themes, to give details in dark shadows.
2) The 3dmatrix was correct, but you have done something wrong.
3) You used D lens. The 3D matrix meter algorithm use distance information for
correction. If you take the same picture, but more distant, matrix will exp.
less. If distance is close exp. more Why? Because the 30000+ picture
experience. In the data base there are more flowers and bugs then slide copy
pictures.
4) What was the position of your camera? I have experienced bad exp. with
upside-down camera. The upper and lower matrix areas are not symmetrical
in calculations!
5) Matrix algorithm use not only relative (transmitted through max. aperture
of lens) but the absolute brightness to recognize the situation. I guess that
your diffuse light through the slide was darker then the real situation. And
the algorithm like to compensate over in dark situations.
Budapest, 1 április 99 csütörtök 14:36:30
dMT alias medve
dr. Moso Tamas e-mail:[EMAIL PROTECTED]
