Resolving Power of BPF 200

[NER]

Gilbert, thank you for your question. Tom, I think you are right. In the end, I will base my decision on several factors, including a few that are not so easily quantified (e.g., how does it "look" when printed). As I said above, the resolving power of the film gives me only one indication of what I might expect from this film: it is not the only factor I consider and my decision to stick with PL 100 will, of course, not be based solely on consideration of that characteristic. I am merely trying to approach this in an informed way vs. methods more haphazard. I would do the same if I were contemplating a new developer or printing paper, i.e., try to estimate how the developer or paper might be different from what I currently use before I spend the time and money investigating it. I don't expect there to be much difference between the films insofar as grain is concerned, certainly not at enlargements approaching 20x24, which is about as far as I can go from 8x10 negatives given the design of my darkroom. I appreciate your observations, and I am not annoyed by your remarks. I was, however, a little exasperated by some of the comments yesterday. My inquiry was a straightforward one which I thought deserved a straightforward answer, not replies explaining how resolving power is affected or counterquestions about my motives, for example.

 

[Tom Stanworth]

I far prefer the haphazard.... continually chasing my tail stops me getting bored as I never win

 

[argentic]

Hi Norman,

In "Post Exposure" Ctein states that the human eye is limited to a resolution of 10 lp/mm on print. But because our eyes are even more sensitive to acutance, we need 30 lp/mm for a print to look perfectly sharp, even if we cannot distinguish the linepairs anymore.

All this goes for a 8x10 inch print. Larger formats need less because you look at them from a bigger distance. 20x24 inch prints would maybe need 12 lp/mm. So, with a film resolving 80 lp/mm this means an enlarging factor of about 6 times. For a 20x24 print you would need a negative of 3,3 x 4 inch.

Considering the fact that your cameralens, the enlarging lens and processing all influence resolution, I guess that with a 80 lp/mm film a 4x5 inch negative is about right for perfectly sharp 20x24 prints. Since you are using 8x10 negatives, BPF 200 has lots of resolution to spare. I guess you will not see any difference between the sharpness of PL 100 and BPF 200 in print.

Ofcourse, the film character, gradation, foot and shoulder behaviour etc. are all important factors to consider. But film resolution shouldn't be when you are using anything larger than 4x5 inch negatives.

Just my 2 cents.

Gilbert

 

[NER]

Bergger has responded to my question. They report that it's 80 lines/mm. Thank you for your interest in this topic.

 

[Howard R. Tanger]

B.T.W. Look at ARISTA.EDU film from Freestyle in L.A. Supposed to be the same as BPF, J&C etc. 8" x 10", 25 sheets, ISO 200 for $33.99.
Howard

Bergger has responded to my question. They report that it's 80 lines/mm. Thank you for your interest in this topic.