How does a grainy large format photo compare to a finely grained 35mm?
Ok, I missed my post due to bad connection. Tried to answer directly to the above quistion with real field examples and calculations.
Will try to summarize what I can recall.
For grain, the only example that can produce finer grain from 35mm film compared to LF, is CMS20.
LF film should be a grainy film like tri x or HP5 or equivalent for comparison, otherwise LF film can sometimes show finer grain.
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.
For fair comparison, 35mm CMS20 film should be enlarged 3.76 times(to make a print equivalent to 5x4), to be compared with 5x4 tri x/hp5 film.
At 5x4 print from 35mm CMS20 film, the grain size will not exceed 1.9micrometer(0.5x3.76), compared with 3.5micrometer for 5x4 tri x/hp5 film.
The CMS 35mm film, can be enlarged 7.5 times, before it shows grain size equal to the grain size of 5x4 tri x/hp5 film.
So, as a conclusion(for grain and for related films and formats), 35mm CMS20 will continue to show finer grain at any print size, compared with 5x4 tri x/hp5 film.
If I proved the obvious, I'm sorry, but it was not obvious for me before finding specific knowledge about grain size of different films(link above).
.
But, a query like that above, usually assume sharpness also implied within!
To answer this, I assumed 2 systems, one for each format, using the same films above.
A decent LF 5x4 system composed of ordinary lens that can resolve 92lppmm and 5x4 tri x/HP5 film, that also can resolve 92lppmm only. This system is not what the best quality LF can provide, also it's NOT the worst.
Another SUPER optical system, that composed of a highly corrected lens that can resolve 300lppmm, and 35mm CMS20 film, that is capable of resolving 400lppmm, for pictorial purposes. CMS20 is claimed to resolve up to 800lppmm, but I do not think for usual photography purposes. More, decent 35mm film lenses, will resolve just a little above 100lppmm:
http://www.takinami.com/yoshihiko/photo/lens_test/pentax_normal.html
I do not think these resolving power numbers from 35mm SUPER system, are what we can actually achieve in reality. Exaggerated for comparison purposes only.
Put the same format factor above, here, 3.76 times.
We need also this equation:
1/Rs^2 = (1/Rf^2) + (1/Rl^2)
Rs: System Resolution. Rf: Film Resolution. Rl: Lens Resolution. ^2: Square.
Appendix, page7:
https://diglloyd.com/articles/Under...er-res-chart/SleicherResChartInstructions.pdf
The LF system can resolve 65lppmm, which within the expectations(but not the best) from ordinary LF system.
The 35mm SUPER system, can resolve 240lppmm, only.
Please repeat the calculations.
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.
At this point, I can say: Any LF lens/film system, can out resolve the best that could be achieved from 35mm CMS20 with the best available lenses, for pictorial purposes.
I know, this is very obvious.
But, what about CMS20 in medium format, with the best available in reality lenses, compared to LF?
I think, this is the question that need to be tested for, not only theoretical calculations and even before knowing how much pictorial character could be retained in CMS20 Medium Format Film.
Hope my assumptions and calculations will not disappoint anybody.
Thanks for reading and indeed for interpretation.
Best.