Thank you for the quick reply.
We agree that it is about a compromise.
My compromise is as follows.
But a few important facts first.
1.a black and white slide needs a much higher contrast than a colour slide (the black and white slide lacks the colour contrast. This must be compensated by a high brightness contrast).
2. a high contrast favours the impression of sharpness.
3. a high contrast favours the representation of fine, low-contrast structures in the slide (example: fine texture in tissue, on stones and leaves, the skin ... This allows a slide to show more detail and convey more information).
For these reasons, a high contrast is essential for a black and white slide.
Figure 2.9 shows approximately the densities and contrast that I consider optimal for black and white slides.
You complain that with the high densities there is a loss of contrast in the projection.
I find that a pity too!
But let's examine together how great this loss really is in practice.
The following zones are affected by the loss of density: Zone I (strong loss) Zone II (moderate loss), Zone III (low loss).
According to the definition of the zones, zones I and zone II do not transport any (very little) information at all, as they no longer have any drawing. Consequently, the loss of density has no effect on the information content of the slides.
If you look at many black and white slides, you will find that many slides do not have any relevant zone I and zone II content at all. So for many slides, the compression of the high densities is without any relevance.
Summary: If the black and white slides have a maximum density of about 4.00, there is a loss of density in zones I and II (III) due to stray light. Only a smal part of the slides are affected by the loss of density at all and the loss of density does not lead to a loss of information.
It remains to be investigated what effect a low contrast of black and white slides has.
I will do that later.
Kind regards
Klaus
We agree that it is about a compromise.
My compromise is as follows.
But a few important facts first.
1.a black and white slide needs a much higher contrast than a colour slide (the black and white slide lacks the colour contrast. This must be compensated by a high brightness contrast).
2. a high contrast favours the impression of sharpness.
3. a high contrast favours the representation of fine, low-contrast structures in the slide (example: fine texture in tissue, on stones and leaves, the skin ... This allows a slide to show more detail and convey more information).
For these reasons, a high contrast is essential for a black and white slide.
Figure 2.9 shows approximately the densities and contrast that I consider optimal for black and white slides.
You complain that with the high densities there is a loss of contrast in the projection.
I find that a pity too!
But let's examine together how great this loss really is in practice.
The following zones are affected by the loss of density: Zone I (strong loss) Zone II (moderate loss), Zone III (low loss).
According to the definition of the zones, zones I and zone II do not transport any (very little) information at all, as they no longer have any drawing. Consequently, the loss of density has no effect on the information content of the slides.
If you look at many black and white slides, you will find that many slides do not have any relevant zone I and zone II content at all. So for many slides, the compression of the high densities is without any relevance.
Summary: If the black and white slides have a maximum density of about 4.00, there is a loss of density in zones I and II (III) due to stray light. Only a smal part of the slides are affected by the loss of density at all and the loss of density does not lead to a loss of information.
It remains to be investigated what effect a low contrast of black and white slides has.
I will do that later.
Kind regards
Klaus
