Lens contrast can mean two things: one is the amount of flare.
Flare is a diffuse light scattered from the interior surfaces of the
lens over the entire image. It affects shadow density more than
highlights and, essentially, puts a toe on the film curve. Lens
coatings significantly reduce flare. Single coatings are most effective
at one wavelength while multiple coatings can be effective over a fairly
wide band of colors. In color flare also affects saturation and purity.
A bright area in one color can cause a flare of that color all over
the image. Multiple coatings can nearly eliminate this effect. The
amount of flare is dependent on the number of glass-air surfaces.
Lenses with few surfaces, like the famous Dagor, have inherently low
flare. Lenses like the many element ones use on 35mm cameras can have a
very large amount of flare if not coated. Lens coating dates back to
the 1930s but did not become general until after WW-2 when methods of
hard coating were developed. Nearly all lenses made after the 1950s
are coated. The presence of coating can usually be told by a residual
color in the reflection from the lens surface. Theoretically a perfect
coating would not have any surface reflection at all but practical
coatings are far from that good.
The other kind of "contrast" associated with lenses is edge
contrast. This is a little more complicated to explain. It has to do
with the nature of the lens aberrations. Some lenses can reproduce
sharp divisions between light and dark areas with excellent contrast
even though they may not have very high resolution. Other lenses may
have high resolution but leave the divisions somewhat soft. A similar
effect can be produced by the development method and choice of developer
which can produce edge or border effects on the film. This edge
enhancement is often called sharpness since the eye interprets high edge
contrast as sharpness even when there is little actual detail in the
image (low resolution). High sharpness developers have often been used
to compensate for low sharpness and resolution especially in 35mm images.
If you are shooting B&W a film with a very long toe, like the
old Plus-X sheet film, may reduce shadow contrast enough to approximate
a lens with more flare. I think currently Tri-X sheet film is about the
only very long toe film on the market. Adjustment of negative contrast
by means of exposure and development adjustments can help but do not, in
general, affect the shape fo the films transfer curve.
For color there is not much to be done although there is some
degree of contrast control available through exposure and development of
negative materials. One effect of very low flare lenses is to
exaggerate the vividness of the color, sometimes not desirable.
On 5/15/2015 9:53 AM, Dennis wrote:
That is what I am having trouble getting my head around. I do use a
densitometer and have very controlled process always using a spot meter and
developing my Z7 density to 1.2 over base fog and my Z1 density to .1 over BF.
So if I adjust my process as I always do to get my zone densities right the
contrasty lens will still be contrastier than the lower contrast lens.
The next stage after film process for my roll film is direct duplicating film
which doesn’t have the same type contrast control of VC paper and the final
stage of my process is pt/pd printing.
Just hard to get my head around overall contrast and lens contrast.
thanks Dennis
On May 15, 2015, at 9:32, Tim Daneliuk <tundra@xxxxxxxxxxxxxx> wrote:
On 05/15/2015 11:28 AM, Tim Daneliuk wrote:==========================================================================================================To
On 05/15/2015 11:13 AM, Dennis wrote:
Hello group.Yes. You can underdevelop to reduce negative contrast. You will also
I am thinking of acquiring a camera with a notoriously contrasty lens. (Fuji
GW 690 type) and my question is this, can the contrast of a lens be controlled
or lessoned (in black and white) through softer film process?
If I have a lower contrast European lens and a higher contrast Japanese lens
can I adjust either to look like the other through film processing?
thanks for the opinions and help
DennisTo unsubscribe from this list, go to www.freelists.org and logon to your
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typically experience some loss of effective film speed when you do this.
The most complete way to figure out how much underdevelopment you
need and how that affects your film speed is to use a densitometer.
However, you can probably get close enough by reducing development about
20% for every stop of contrast you want to pull in, and expose your
film at 1/3 stop less. This is a guestimate, but it will get you going.
I should also mention that my consistent experience *using* a densitometer
is that - if your meters and thermometers are reasonably accurate - most
film needs be exposed at 1/2 rated ASA and underdeveloped about 20%
for *normal* contrast.
Now then, I'm not sure why any of this is necessary in the case of the GW 690.
Modern VC papers have more than enough range to be able to pull in the
contrast of the lens to where you want it to be. If you're not printing
silver, but scanning, the same applies to digital manipulation.
Expose your negatives to capture the widest possible range of light appropriate
for the subject then manipulate in the darkroom/computer for effect.
IOW, get it on the negative and throw it away later.
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