Re: [Leica] Kodak versus Fuji: is that the issue?

["Tom Schofield" <tdschofield@email.msn.com>]

Erwin,

    Thank you for this enlightening post.  I just went through choosing a
film to take on an upcoming tip to Europe, and finally settled on Provia F.
My queston is whether in actual use the extra 1-2 stops speed advantage
overcomes this slight, comparative, softness.  Obviously, for hand held
pictures the reduced camera shake can be a big advantage, and even with a
secure tripod mounting, there still is subject motion, such as plant and
trees blowing in the wind.  Years ago, when A&I lab in California was the
leading slide printer, and advocated Kodachrome exclusively, They stated
that their printing results favored K64 over K25 for this reason.

A second question is whether you have noted a difference between the amateur
and professional versions of Kodachrome for the same speed rating.  On
Kodak's website, the gain specifications are significantly better for the
professional versions.

I look forward to your comments.

Tom Schofield

PS  I also enjoyed your report on the APO Summicron 180mm.  I adore this
lens, having obtained a used one in a trade deal at a camera show.  The
selective focus effects are fantastic - redefining Bokeh!  I have, however,
been successful hand holding this wonderful lens.  The mass seems to help
reduce shake.  Admittedly, my forearms were sore after the fist time or two,
but no pain, no gain, right?

- ----- Original Message -----
From: "Erwin Puts" <imxputs@knoware.nl>
To: <leica@topica.com>
Cc: <leica-users@mejac.palo-alto.ca.us>
Sent: Sunday, April 23, 2000 12:37 PM
Subject: [Leica] Kodak versus Fuji: is that the issue?


> The topic of which film has the better sharpness impression and/or
> lower graininess, and which measurement is the best merit figure to
> evaluate a film is an interesting one and could fill a book to
> elucidate in considerable detail.
> Let us first establish some baselines. A film has a number of
> measurable properties, like RMS values (for the random fluctuations
> of grain patterns), MTF-curves for a relationship between contrast
> loss versus spatial frequency, resolution value for the propensity to
> differentiate between closely spaced adjacent point/line objects and
> so on.
> At the other end we have perceived, that is subjective, qualities of
> a film. like the impression of sharpness or graininess.
> If all would be well, the measurable properties should correlate
> closely to the perceived qualities and more importantly a shift in
> magnitude in one dimension should be proportional to a shift in
> magnitude in the other dimension.
> Alas in our real world it is not that simple. Sharpness impression is
> related not to the fineness of the grain pattern, but to acutance,
> this being a property of an emulsion. Acutance can be explained as a
> rapid drop in contrast between two adjacent areas with different
> densities. A grain structure that diffuses the incoming light energy
> has by definition a higher propensity to scatter the light rays and
> so to lower the edge contrast. (= acutance). E-6 emulsions consist of
> dye clouds after development and while these clouds show a very low
> RMS value (low graininess), they also diffuse the light rays and
> lower the acutance. K-films are grain based and while the graininess
> impression is a bit higher they exhibit better edge effects and so
> enhance the sharpness impression. The perception of grain is lower
> when the very fine details are resolved quite good as in this case
> the randomness of the density patterns of the grain clumps or dye
> clouds reside behind the image structure that is recorded.
> Looking at MTF graphs we may note that the sharpness impression is
> enhanced if the contrast figures are very high in the 5 to 10 lp/mm
> range. If a film has a value higher than 100% (which should be
> impossible) than the edge contrast is artificially enhanced. But the
> recording capacity of a film is closely related to the contrast value
> at 40 to 50 lp/mm. BUT: differences in contrast value in the
> bandwidth of ±10 percentage points are not relevant. So a film that
> has an MTF value of 40 at% at 50 lp/mm is as good as one with a value
> of 45 to 50%. At the other end of the scale minor differences are
> important and a contrast transfer of 115% is significantly better
> than one of 110% at the same spatial frequency.
> When I did a series of tests with K25/64 and Fuji Velvia and
> Provia100F (disregarding the saturation issue here), I found that the
> graininess impression of all four films (when comparing homogeneous
> areas of equal density) was very low and any difference would be
> irrelevant for most photographic purposes with high quality lenses
> (Leica ) and 35mm film at large scale projection. At this level
> differences in graininess are most likely explained by slight
> differences in exposure and with all films every possible detail
> could be recorded.
> The K-films however recorded the same details with a better edge
> contrast and details were crisper and  delineated  with  engraving
> like edges. Provia 100F had a definitely softer look, but in all
> fairness had somewhat less detail definition, compared to Velvia and
> the K 25/64.
> We are however at a level of definition of details and a quality of
> recording capacity that is at the edge of what a lens can handle and
> the technique of the photographer is presumably the limiting factor
> here.
> The overall impression then is that all four films handle the
> recording of object details very well, grain of all four is beyond
> the level of perception, but the K-films record details with more
> edge contrast and   in doing so have a slight advantage. Velvia has
> the finest grain of all four, but as said above the difference with
> K25 and 64 and Provia F is so small as to be irrelevant, but to be
> fair again can be measured. As with speed of a car, you can measure a
> difference between 110 and 112 km/hour, but you can not experience it.
> For ultimate recording capacity the K-films still have the edge, it
> is not a very big  one, but in many instances a significant one and I
> would propose that we should not try to establish an absolute
> difference between these four but develop our technique to exploit
> the characteristics of our film/lens combination to suit our goals.
> My films of choice are K25 and 64, because of their higher fidelity
> when recording the reality in front of my lens. Comparing K64 with
> P100F at a large screen is no contest: Kodak wins on all visual and
> perceptual counts. In this sense the Velvia and Provia are not in the
> same league, but these films have really awesome capabilities and we
> should not indulge ourselves in an either/or discussion, but
> appreciate the differences as they are and use then when appropriate.
> It is really a pity that Kodak has lost all interest in these
> K-series as they could be the cutting edge in emulsion technology.
> But Kodak also has lost interest in the traditional B&W films.
>
> Erwin Puts
>
>
>