A comparison of fine grain
black & white film and digital images.
Except for artistic
reasons, when shooting film, most photographers are concerned about excess
grain and try to eliminate it as much as possible. Unfortunately, that cannot be achieved all
the time. It is an accepted fact of
photographic life that faster films do display more grain than their slower
counterparts. Obviously, we have to
match the films we choose to the lighting conditions under which we take
photographs.
Grain is also very closely
associated with sharpness and detail in a photograph. A coarse grain film simply cannot show as
much detail as a fine grain film. Fine
grain films are therefore inevitably sharper and for that reason more
desirable.
The slowest black &
white films on the market used to be Kodak Technical Pan, Agfapan APX 25, Efke
KB 25 and Ilford Pan F. The Kodak Agfa
and Efke films had a standard rating of ISO 25, while the Ilford had a rating
of ISO 50. All three of them were outstanding
examples of modern, fine grain films, and must be considered the best the
market had to offer.
Kodak Technical Pan
basically was a slow, high contrast film with extended red sensitivity, meant
for copying of documents etc. In the
appropriate developers, the film would display extremely high contrast as is
necessary for such work. However, when
developed in Kodak Technidol or similar developers, the film would display a
continuous tonal range with near normal contrast. If we go strictly by published specs, there
is nothing comparable on the market.
Technical Pan had finer grain and a higher resolution than any other
film readily available. This should make
it the undisputed leader in the fine grain film field.
Technical Pan could
deliver negatives of incredible sharpness.
However, since the film was basically a very high contrast material, it
did suffer from relatively high contrast, even when developed in
Technidol. When used in bright sunlight,
the results were fairly contrasty, too much so for a lot of photographers. The
film also had a low exposure latitude and required a very specific developing
procedures to make it useful as a standard, pictorial film material.
While the performance
potential of the film was unquestionably very high, it remained a special
purpose film with considerable limitations.
The Ilford Pan F is
certainly a tremendously capable film, but by virtue of its higher speed, it is
not quite capable to deliver the performance of the Kodak Technical Pan or that
of the Agfapan APX 25 and Efke KB 25.
The Ilford film therefore has to be considered to be on the bottom of
this list.
As far as published
specifications go, the Agfapan APX 25 and Efke KB25 are not quite as sharp and
don’t have quite the fine grain of the Kodak Technical Pan. On the other hand, the films easily allow
adjustment of contrast by changes in exposure and development times. In addition, they do not require special
developers. Any good black & white
developer can do an outstanding job with these films. One such developer is Agfa Rodinal. Rodinal is not a particularly fine grain
developer, but it displays a very high acutance, which yields extremely sharp
negatives. Agfapan APX 25 and Efke KB
25, developed in Rodinal, have proven to deliver negatives of exceptionally
fine grain. Enlargements of 15 times
have proven to be virtually grainless, and even enlargements of 30 times are
still quite acceptable. Of course, this
is also very much dependent on the quality of the camera equipment.
The question is often
asked if APX 25 or Efke KB 25 couldn’t deliver even finer grain if a so called
fine grain developer was used. The
answer is certainly “yes.” But why? If 15 or 20 times enlargements from these
films, developed in Rodinal, show virtually no grain, why try to reduce grain
size? It wouldn’t make any visible
difference. However, the coarser grain
structure of high acutance developers usually renders a greater apparent sharpness. A finer grain developer therefore might have
the effect of less apparent sharpness due to lower acutance.
Reduction of development
times in Rodinal will lower the contrast of the negatives while an increase in
development time will result in the opposite.
In addition, the film can quite successfully be pushed to a rating of 50
and still yield very good results. The
film can also be pull processed at a rating of 20 or 15, to yield even finer
grain. This will also result in a
noticeable reduction of contrast.
It is this versatility
which ultimately made the Agfapan APX 25 and Efke KB 25 more desirable films
than Kodak Technical Pan. Given the
right lighting conditions, they are without question some of the best black
& white films ever made.
This photograph shows
approximately the entire negative area.
It was scanned from an
enlargement which was carefully adjusted
during printing to render
an exact 8X magnification.
This cropped section of
the original negative was scanned
from an enlargement,
adjusted during printing to be an
exact 16X enlargement
A section of the same 16X enlargement, scanned
from the original print.
This portion of the
negative was scanned from a 35X enlargement.
The very fine eye lashes
in the upper left corner have an approximate
Diameter of 0.007mm
(0.00028 inch) on the negative which translates to a
resolution of over 140 lpm
(lines per millimeter) on the enlargement
which means that the
on-film resolution is even higher.
Please note: All black and white image were scanned from actual enlargements on photographic paper, not from the original negatives
Unfortunately, the
overwhelming popularity of digital photography has influenced the photography
market to the extent that many films have been discontinued. Of the fine grain black & white films,
only the Ilford Pan F remains at the moment and therefore has to be considered
one of the best currently available.
Of course this brings up
the question if digital cameras are capable of delivering images of equal
quality and the answer is; definitely, providing we are talking of camera
equipment and especially lenses of equal quality. As a matter of fact, given a sufficiently
large sensor, especially full 35 mm frame sensors with sufficient resolution,
the same lenses might deliver even higher quality images with a digital camera.
The limiting factor of
maximum resolution on film besides grain size is the fact that light will
scatter within the emulsion. This
definitely reduces overall resolution and it is the very reason why films will
never be capable of delivering all the resolution, all the detail that a high
quality lens is capable of. In
comparison, most digital sensors do not have this scatter effect, meaning that
a less quality reduced image can be produced.
Of course the ability of the digital camera system to suppress noise and
other image degrading phenomena are a factor also.
Following is a photograph
taken with a digital camera that shows that comparisons to even the best 35 mm
films present no problem. I purposely
chose the Leica Digilux 2 which has a modest resolution of only 5
megapixels. However, it should be noted
that compared to consumer cameras with similar resolution, the Leica Digilux 2
has a relatively large sensor that allows for larger individual pixels. The result is a higher image quality,
especially if the camera is used at lower exposure indices. It is obvious that in spite of the relatively
low resolution, the resulting images compare quite favorably with the above
black & white images taken with exceptional camera equipment and
exceptional film.
Image uncropped
Image cropped from the original file
Image cropped from the original file,
equivalent to a 27 x 36 inch full frame
image
The sharpness of the
images shown is such, that some of the small detail is so fine that it wouldn’t
show on an enlargement unless enlarged to approximately 16 x 20 inch. This is for instance the case with the above
black & white images. On an 8x10
enlargement, the very fine lashes are invisible.
Needless to say, a full frame digital camera with the same quality lens would have rendered better results.
Technical Data
Black & White Images
Camera: Leica M3
Lens: 50mm Dual Range
Summicron f/2
Film: Agfapan APX 25
Light Source: Broncolor Impact with 25” soft
light reflector
Developer: Agfa Rodinal 1:100, 68º F,
16 Minutes
Enlarger: Leitz Focomat V35 with
Leitz Focotar, 40mm f/2.8 and color head module
Technical Data
Color Images
Camera Leica Digilux 2
Lens 7-22.5 (28 – 90 equiv.)
Leica DC Vario-Summicron f/2 – 2.4
Exposure Index ISO 100
Light Source Speedotron Brown Line D402 and
D802 both at 200 ws with umbrella and reflector fill
________________________________________________________________________________________
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The big problem, it seems to me, when comparing film to digital is that the influence of the scanner on the results is usually not mentioned. I have read comments by supposedly competent photographers that they find photographs they have taken with film have as much resolution as a 6 megapixel digital camera. On the strength of this they go to say that digital images are better than what you can get with film. What they should have said is that their scanner is only capable of producing images comparable to a 6 megapixel camera. Scanners do not reproduce faithfully the full range of detail contained in a slide or negative, and so the comparison is false. If one wants to make a fair comparison I think the scanner needs to be eliminated from the image chain. Let's see the results from film when a proper V35 Focomat enlarger is used instead. An even better way to do it would be to project side by side on large wall screens a slide and a digital image and see which is better. So far I have never seen any digital projected image that can even remotely compare in quality to what a beautiful colour slide shows.
ReplyDeleteYou are correct that a scanner is incapable to show the entire image as it is on film. Any time you produce a second generation image, there will be certain losses in quality. But the same is the case with negatives when enlarged, even with a high quality enlarger like the Focomat V35, and it is the same when projected. subsequently, regardless how we arrive at the final image, it will inevitably incorporate those losses. We also have to look at the influence of the receptor, be it film or a digital sensor. The image, as produced by the lens, will deteriorate within the emulsion of the film because of the scattering effect, as pointed out in the article. This is more noticeably the case with color films because all of them do have three emulsions layers compared to just one for black and white film. Some sensors do have an advantage in this respect because this is not the case here. But as I also pointed out that the electronic processing of the signal or image does have negative effects as well. This is reduced to a minimum by eliminating the anti aliasing filter or, as in the Leica M Monochrom, by eliminating the bayer filter. Given a high quality sensor of the same size as a 35mm negative can ultimately achieve a higher quality image than film. If the final result will show that is entirely dependent on how we arrive at the final image.
DeleteFabrice SA wrote:
ReplyDeleteVery interesting
and very good démonstration