I can confirm that both by the results of my scientific film resolution tests, and by the talks with Kodak at the introduction of Ektar at Photokina 2008.
Portra 400, Ektar 100 and Ektachrome 100 have all a measurable lower resolution at medium and higher object / detail contrast ratios in comparison to their forerunners. That is clearly visible when I evaluate the test results at medium to high magnification.
Kodak has put the priority on finer grain. The main reason for that is that today the huge majority of colour films is scanned. And most current scanners have two characteristics:
- they are sensible to grain, grain is most often visibly enhanced (exception: real drum scanners)
- they are not able to record the full resolution of film; the resolution capabilities are relatively weak: depending on the scanner type and film type you loose 20-80% of the original film resolution (I have tested that with many scanners up to the best drum scanners).
If you want to use the full resolution of film optical enlarging with excellent enlarging lenses and projection with excellent projection lenses are the way to go, by that you surpass even the best drum scanners significantly. And you can use almost the full resolution potential of film.
That's only a part of the story. The high frequency information transmission capacity of a given emulsion is effectively limited by the granularity (quite severely) and/ or where the MTF response falls off (as that enhances the visibility of the granularity). Therefore if you design an emulsion that has extremely high low frequency MTF response, and a slightly faster roll off at high frequencies it'll look both much sharper and finer grained than one that has a less strong MTF response at lower frequencies and a longer roll-off at higher frequencies. In the real world, despite what high contrast resolution tests might suggest, there are very real limitations as to how much useful resolution a given opto-mechanical system can record on film, but getting the highest possible MTF below 40 cyc/mm will look dramatically better perceptually than any of the claims over whether an extra 10 lp/mm at high frequencies makes a difference. The really severe limitation with scanning is that scanners (and for that matter, all digital sensors) cannot deliver 100+% MTF response at low frequencies, whereas fully optical/ chemical systems can add quite significant MTF boosts with each neg/ pos/ neg/ pos step, to the point that the industry literature has long warned about the problems this presents for emulsion designers if the resultant print is not to look rather strange - that effect, combined with a faster fall off of MTF on a print will again combine to make a fully optical print look seemingly often finer grained and sharper in a cleaner way than one that has been digitally sharpened.
And that is what really matters in making convincing big enlargements - not whether a film can resolve a high contrast target at 110 or 120 lp/mm (the micro-fine detail difference is of no matter to viewers who aren't aerial recon analysts), but an enlarging lens that's up to resolving the visible granularity of the material at 30x (average viewers can see a difference between a very high res scan and a fully optical print, though because of social conditioning, they usually make the wrong differentiation) - and even here, the low frequency characteristics matter a lot. The much worse low-frequency MTF response of most transparencies is a real problem here unless the original transparency is the final imaging stage with no further reproduction steps.
And I then started the tests together with the SCALA expert at Photostudio 13. And the result was quite astonishing and very positive, with very nice results. The only significant restriction was the minimum development time of the FD in the special Refrema dip-and-dunk processing machine for the SCALA process (3:15 min.). Therefore a pull-development was not possible for this film. But that was a limitation by the machine, and not the film.
You can see the effect I summarised in your results too - while the midtone gradient is being brought down to a reasonable level, the toe and shoulder remain very sharp - very much a fundamental function of the emulsion - and not something that process alteration is probably going to alter significantly. In the right circumstances it can be aesthetically successful. With neg/pos, it's possible to get round that problem more effectively (squeeze more on to the straight line), but for reversal it's a problem.
In other words: I wound't waste my precious eFKe films (or any other not-produced-anymore films) to try to reverse them, although I know they will reverse very well...
I would be very wary about putting a Fotokemika emulsion (or anything with that level of hardening through the Agfa Scala process - the fact it seems to have sulphate in the FD indicates that it's exerting a fair amount of stress on the emulsion with the PEG, never mind the carbonate. There was no emulsion damage with the last surviving version of the Agfa Scala process and Agfa, Adox (Scala 160), Ilford or Kodak emulsions in my experience, though it did show the extent to which Scala 200x was ageing. Was mainly interested to see if it could be used to eliminate a step in making enlarged internegs for various processes, but it did become obvious why neg/ pos has advantages (sharper, finer grained), just as all the research from the big manufacturers showed...
Are you stating that the finest grain a film has (or a developer imparts to a film - it comes to mind Perceptol for example) the less sharp a film is?
Dilute Microdol was apparently the reason Kodak never made a Rodinal clone, if you want to spend an afternoon cross-referencing some of Henn's commentary with pH/ sharpness distribution curves. Improving sharpness without worsening grain remained an area of active B&W product (vs basic) research for a long time at the big manufacturers - especially after DIR couplers in C-41 appeared. Without giving too much away, there are good reasons why fairly solvent PQ developers (and revised emulsion structures) all appear quite close together. The route to Ilfosol 3 seems to have been different, but not sui generis (earlier ideas on parallel and much more chemically advanced lines relating to cross-pollinating from C-41's non solvency but very fine, sharp grain had been discussed by Haist and Mowrey).
For the record, Ilfosol 3 is much sharper than Rodinal, and finer grained - but because of the heightened sharpness the grain is more visible than something like D-76.
I always thought that sharpness could be related to how much the gelatine swells.
This is probably also of interest to
@Ivo Stunga
Emulsion thickness is a big part of it - and how much 'stuff' has to be packed in. Agfa fortuitously gave the data for their films - Scala 200x (and APX 100) was a 7 micron emulsion layer, whereas RSX E-6 colour transparency was something like 25 microns total in multiple layers (by way of comparison, the C-41 films were under 20 microns and APX 25 was something like 3 microns). I recall that Fotokemika's single layer emulsions were something about 12-14 microns (thin for 1950), so Foma R100 is probably somewhere in the middle. The really instructive bit of data though is the MTF and RMS
granularity for APX 100 and Scala 200x (they seem to have been essentially the same emulsion in all but silver/ m
2 (at least one reviewer seems to have befuddled themselves with this) - this is part of why technical films will often reverse well - they are designed to deliver high contrast, so they have higher silver/ m
2, which specifically aids reversal characteristics - it's of no benefit for regular moderate contrast usage in neg/ pos) which rather clearly shows the impact of reversal process (the higher contrast outcome of reversal does compensate somewhat) on overall sharpness and usable data transmission of the two processes - which you can very clearly see when you print from both of them.
@Ivo Stunga one other characteristic that Fuji apparently achieved with some of their E-6 materials was enacting a form of DIR coupler in the 1990s, which Kodak never managed/ tried to do - R&D seems to have been much more invested in C-41. There were some components that had to be changed across almost all films in the late 2000's/ early 2010s that seem to have been plasticisers/ gelatin extenders - they may have had an impact on aspects of sharpness in E-6 materials. As we have seen recently, it seems Fuji guessed wrongly about the market and got caught on the hop with some of their products needing environmental changes - which they'd clearly decided not to do on their own (wrong) guesses that demand would continue to decline.
, Chris.
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