Before anybody wonder, how can the 35mm CMS20 film that resolved 240lppmm(with SUPER lens), enlarged 3.76 times, to make 5x4 print, for comparison with 5x4 triX/HP5 film ?Making 5x4 print from the 35mm SUPER system(enlarged 3.76 times) for fair comparison, the print will only retain 64lppmm, which is equal to what a modest LF system can achieve.
The system resolution equation, has been invented long time before any digital was invented.1) You are analyzing film grain size as if they are pixels. Film grain is not equivalent to digital pixels which have a defined sampling frequency. Film grain size is a distribution which is centered on a certain size but does not distinctly sample at that corresponding frequency. Early in my optical engineering career I used to try to do the same but it’s simply an incorrect way to analyze a film-based imager.
The quote above has enlighten me.your analysis is flawed because the spatial frequencies imaged with 35mm vs large format lie on different regions of the film’s MTF curve. This is important because as spatial frequencies increase, the contrast decreases until it reaches 0 at the sampling frequency of the imager. So for CMS20 the contrast is going to be very low at 300 lp/mm. Details in the scene that approach this value will be very low contrast on a 35mm print. The optics come into play as well. Those details will also be softer due to the optical MTF. When shot with a large format camera the sampling frequency for the same scene detail will be much lower (I think at a ratio of the lens focal lengths used but don’t quote me). Since it is a lower spatial frequency as imaged by the large format camera, the contrast of that detail will be much higher due both to the film MTF and sharper due to the optical MTF
Post number: 19Adox CMS 20 II, Spur Modular UR New or Adotech II developer: 240 - 260 Lp/mm.
It seems to me that the OP was asking a very specific question out of academic curiosity. If our aim each time a question is asked is to respond with answers that we hope will answer the questioner then we need to know if we have succeeded.
So Trondsi, have we answered your question and satisfied your curiosity? Thanks
pentaxuser
There are a lot more variables involved in real-world photography and printmaking than just this kind of hypothetical number crunching. Lots of people don't even know how to keep the film flat in the enlarger. Fewer still know how to keep film truly flat in a view camera. Even the specific developer protocol with respect to any film can affect perceived acutance. So can the type of paper surface. Often "grainier" large format films yield sharper-looking results than fine-grained films. I work in multiple formats and switch strategies accordingly. If someone simply enjoys number-crunching, that's fine with me. But it won't necessarily give you the kind of answers you are hypothetically seeking, certainly not by itself.
I am just curious. Say if you took similar photos with 4x5 and 35mm. For the 4x5 you used a grainier (probably ISO 400 or higher, I can't remember seeing 800 in large format lately) film, and for the 35mm you used, perhaps, ISO 100 or finer. Perhaps you need larger differences for them to be more comparable (50 vs 800?). How would the two photos compare? Would the formats vs grain "cancel out"?
hi trondsi
do you have a LF camera and a 35mm camera ?
why don't you burn 2 sheets of film and 2 rolls of film and compare your images ?
if you are going to scan your negatives it might not matter
but with physical prints and depending on the type of enlarger you have
and how you processed your film ( all of it in rodinal or xtol ) ..
you could probably do film and print and developer tests for weeks
its a long rabbit hole to crawl into .. and you would learn a lot about processing,
film and printing ... and comparisions between probably 70 different film and print developers
have fun !
john
I might do something like this. I usually scan my film though, and my flat bed scanner is not very good (it works best on medium format actually). I just do this as a hobby.
This started with a bad assumption, based upon the diagonal!Based my conclusion on the grain size of other films like Tmax400 and Velvia:
http://www2.optics.rochester.edu/workgroups/cml/opt307/spr04/jidong/
Tmax400 grain size= 2-3 micrometer
Velvia50 grain size= 0.8 micrometer
So, safe assumptions(as far as I understand) of grain size of 3.5 micrometer has been assumed for tri x/HP5 film, and 0.5 micrometer for CMS20.
Considered also, enlarging factor(of 3.76 times) between the 2 format sizes, obtained by dividing diagonal of 5x4 film by the diagonal of 35mm film to compensate for aspect ratios differences.
Another advantage of larger formats is less visible scratches and dust for a given print size.
Nodda, I do my homework when buying lenses. You obviously do it when engineering optics. I have many years of hard science in my background, in several fields. I also know how to make far sharper prints than the average darkroom worker (this being just one more tool esthetically, and not necessarily an end unto itself). And I've learned how to get from Point A to B pretty efficiently when designing my own equipment. Watched one of those PBS documenmtaries the other nite which was
related to just how precisely the Egyptian pyramids were built millennia before modern methods of calculation. There's more than one way to skin a cat. I don't attempt to make my own lenses or intricate solid-state circuits. But if I deserve an honorary phD it's in Jerryrigging and Cannibizing equipment and coming up with new ways of doing things more efficiently. Yes, I have my calculator too; and have even concocted customized math models for certain exposure situations where I basically had to write my own Owner's Manual to my own specialized equipment. But on forums like these, it's getting rather predictable for inexperienced people to get quickly lost in the woods by overthinking things. And it reminds of hikers in literal woods stumbling over logs and rocks, and potentially injuring themselves because they spend all their time staring at some stupid GPS device. Our own eyes are actually a far more sophisticated piece of equipment.
Thanks indeed wiltw for your interpretation.But 8.46x mag of 0.35 micrometer grain vs.
Please read the whole post.While a recent 5x4 LF APO lens can give 60% MTF(center) at spatial frequency of only "20" cycles/mm, an equivalent focal length MF lens produced 67% MTF(center) at frequency of "40" cycles/mm. It's double plus extra performance.
Review MTF of Schneider APO-Symmar L 210/5.6, and Zeiss Hasselblad Planar CF 100/3.5 .
Both lenses will show about the same field of view, but at roughly double size image on film, which could be compensated for by the great(double) difference in MTF performance.
At this specific example, if tmx100(or CMS20) was used in MF and on the other hand a trix/HP5 was used in LF, I think MF will give hard time to LF(if not out resolve it).
No wonder, I've seen MF prints that can be compared(NOT clearly exceeding) in sharpness, to 5x4LF prints at sizes up to 60x50 cm.
All this reminds me of an old RollsRoyce story, Someone wrote the factory and asked: I am interested in buying an "X" model of your cars. How many horsepower does the "X" model's engine have? The answer came back with one word: "enough". If my 35mm cameras can take "sharp" 11 x 14 prints, they are sharp "enough" for me. If I make a 4x5 picture and print it to 11 x 14 also and it is sharp also, then it is sharp "enough" for me. I am the only one those formats and lenses have to be sharp "enough" to please..........Regards!A grainy 4"x5" negative focused with a grain focuser will be much finer grain than a 35mm fine grained negative focused with a grain focuser for the same size print.
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