Re: [Leica] Exploring the limits (part 1 of several)

[Stephen Gandy <Stephen@CameraQuest.com>]

Your results are very interesting, and bring up very worth while questions, but
I think you may be jumping to conclusions without sufficient data (based upon
the information you supplied here).   One set of test data only proves the
result for that particular test series.   Many similar test results, from many
different photogs, on the other hand, would seem to prove your points.

Since your results are so different from the film manufacturer's, why not
contact them, explain your methods, find out the basis of their claims, and
hopefully determine together how the results could be do different?  Surely they
would be happy to hear from you, it would give them a chance for independent
confirmation of their claims -- IF they are correct of course.

Your three lens choices listed below are so different I don't see how much can
be learned from the comparisons:  the highest priced current production 135
manual focus lens vs the highest priced 28 to 50 vs a Canon 50/1.8 that often
sells for $50 or even less here in the US.   The caps on the Leica lenses you
tested cost more than the Canon lens.  BTW the Canon 50/1.4 FD generally has a
better reputation  than the 50/1.8 FD, which was Canon's least expensive 50 mm
SLR optic in FD mount.

Why not compare Leica vs Nikon vs Canon of the same or nearly the same
approximate age, focal lengths, apertures,  and price ranges (ie the best that
Nikon, Canon, Leica offered in a particular focal length?     perhaps three
50/1.4's,   or the 90/2 vs the Nikon 105/2.5 or 85/1.8  vs the Canon 85/1.8 or
105/2.8  if you want to compare each manufacturer's approach to resolution vs
contrast ?

The issues you bring up here are important an useful.   I especially look
forward to the reply from the film manufacturer explaining how the two test
results could be so different.

Regards,

Stephen

imx wrote:

> I have been testing the new Gigabit high resolution film since several
> months and what began as a simple filmtest, has now been expanded into a
> fresh exploration of film and lens capabilities. My results surprise me as
> much as I hope it will surprise the readers of this report. An open mind is
> necessary, however, as many established ideas have to be discarded!
> The Gigabit film has been promoted as a new dimenson in Hi-res BW
> photography and a useable resolution of 600 to 900 lp/mm (every line pair a
> black and a white line or space) has been quoted. In several usergroups this
> claim has been discussed to the extreme: could it be possible theoretically
> and if so could there be lenses that can use this capability.
> First the basic fact: the resolution of the eye: under ideal circumstances
> the eye can resolve at a distance of 25cm at most 6 to 10 lp/mm and here we
> take the absolute limit, which is reached when the eye is using its vernier
> acuity resolving power. Six lp/mm would be according to all ophtalmic
> handbooks a good average. This means that any detail which is smaller than 6
> lp/mm cannot be detected as separate lines and will be seen as a grey patch.
> A simple calculation shows that to be able to see details that on a film are
> recorded with 600 lp/mm, we need a magnification factor of 100 times.
> I started using a high quality microscope with a magnification of 40, 100
> and 400 times. Then I used a testchart with lines and circles (as the
> pattern itself will influence the resolution limit). I set up the Leica in
> front of the testchart at a distance that gives a negative magnification of
> 100 times. The idea was that when using the microscope at M=+100, I would be
> able to see the resolution pattern that is closest to the 600 lp/mm. I used
> the Apo 135 as this one is capable of resolving at least 300 lp/mm at a
> acceptable contrast and even 450 lp/mm at a very low contrast (less than
> 10%).
> To ensure optimum results I used of course the center portion of the
> negative and to make sure film flatness and focussing errors are not a
> problem Iused the following setup. A Siemens Star was used to check accurate
> focusing (a phase shift in the pattern will indicate a focus error) and I
> did extensive focussing bracketing by marking the distance on the lens and
> taping scaled paper on the mount to accurately make my bracketing.
> Result one is that the lens and the camera focussed extremely accurately
> even at 13,5 meters with a 135mm lens, which is reassuring in itself.
> I shot three films and checked every negative under the microscope to find
> the best results. As resolution tests always involve errors in viewing, I
> used the best 10 results and averaged the numbers to get a result that is at
> least in principle reproduceable by anyone.
> To my utter surprise the microscope revealed at most 60 lp/mm!! (IN one
> instance I read off 90 lp/mm, but that is the extreme case, which I could
> not reproduce later on). So 60 lp/mm is the practical maximum resolution?
> But: what is the limiting facor here: lens or film and where are those
> mythical 600 lp/mm?
> Back again to the testchart, now with a Summicron 50 of latest design.
> Repeat the whole procedure and I got somewhat lower figures, around 50
> lp/mm.
> Now some people assert (wrongly, but it is common view) that leica lenses
> are optimized for contrast and not resolution. To counter this (you see what
> you have to do to get a reliable test with meaningful figures) I used a
> Canon F1 with a 1.8/50mm lens, reputedly a high res lens. Results did not
> differ: no significant and statistically relevent difference in resolution
> between the Leica and Canon lens. I used as a third test a TriELmar at the
> 50 position and got again results around 50 lp/mm. So obviously the lens is
> not the limiting factor and so the results found (60 lp/mm) must be film
> based.
> Could the spectral composition of the light be a factor.
> I used all light sources, flash, daylight sun and tungsten halogen light to
> look for differences: none found.
> Then we need comparison films to investigate further.
> APX 25, APX 100, Delta 100, Pan F, TMax100 and Technical Pan were selected.
> As Gigabit film is standard Agfa Copex Microfiche film (no new emulsion this
> Gigabit! Only new is the developer, but wait and see later) and TP is also a
> micro-film, which are "forced" to go for continious tone negatives, I
> wwanted to use films designed form the start as continious tone film as a
> comparison.
> Surprise two: using the same procedures and testing developer-film combos
> with D76, FX39, Rodinal, TMax, the best film combo for resolution is TMax100
> in FX39, which even surpasses the APX25!
> To be continued!
> Erwin
> The first check