Very Slow Emulsions and Resolution compared to Daylight Emulsions

[Mustafa Umut Sarac]

I dont know where and when that idea inscribed to my memory but AFAIK slower resolution emulsions have higher resolution and better degrades. Is it true ?

Umut

 

[dE fENDER]

It is. Some microfilms have sensitivity from 0.05 to 6 ISO and up to 1000 lines/mm on contrast edges. T-max 100 has only 200 lines/mm. And you can search for some tests of Adox CMS 20 (800 lines/mm) which is very demonstrative..

About degrading - it you will try to develop a lot of old films, you will notice that your second statement is true too - high speed film will has a lot of fog and their high iso falling down to 3-6 iso, but low speed films with 3-6 iso hold its original speed.

 

[Mustafa Umut Sarac]

Thank you Moscow,

I learned two important things.

Now the important another question , I know bw papers have low iso , are they able to record high resolution also ?

Umut

 

[Rudeofus]

Now the important another question , I know bw papers have low iso , are they able to record high resolution also?

Yes, grain of photographic papers is very fine, and the granularity you see on prints almost always comes from the enlarged negative.

Note, that if you use anything with an aperture (lens, pin hole, ...) to create images on your medium, these 1000 lp/mm resolutions don't gain you much image resolution. Anything beyond 100 lp/mm is probably a waste of effort outside very carefully constructed lab scenarios.

 

[Mustafa Umut Sarac]

Anything beyond 100 lp/mm is probably a waste of effort outside very carefully constructed lab scenarios.

What happens adox 20 , 800 lpmm films capacity when it matches with 100 lpmm lens , I thought that and only answer , the film can capture the aberrations around points. I dont know whether this is good or bad. Any thoughts ?

 

[kb244]

I've found this to be true in my very limited experience, mainly with orthochromatic lithography film. Like when I shoot Ultratec as ISO 3 or 6 in 35mm I find it to be extremely sharp and fine grained, and next to nothing that would resemble aging from being expired so many years later.

 

[Rudeofus]

Umut, a simple approximation if you have a medium with resolution X lp/mm and a lens which can do Y lp/mm, is that the cumulative resolution of this system Z is calculated as 1/Z = 1/X + 1/Y. This formula looks a lot like the formula to calculate resistance of two resistors switched in parallel, although the physics background is, as you can imagine, quite a but different.

Either way, the combo suggested by you would give 1/Z = 1/800 + 1/100 = 9/800 ----> Z = 800/9 = 88.9, which is slightly below the lower resolutions of the two components, in your case the lens. Note, that this lens will give you optimal resolution at just one aperture - open up and the lens gets more blurry from optical defects, close down and you get blur from diffraction.

 

[Gerald C Koch]

This is one of those situations where one must be careful identifying a necessary condition from a sufficient condition. The terminology here is borrowed from mathematics. A necessary condition is one that must be fulfilled. However in itself it is not sufficient to guarantee the result. There are many necessary conditions such as emulsion thickness that effect resolution but there are none that are sufficient. So you cannot say without uncertainty that a slow emulsion will have good resolution.

 

[Maris]

....So you cannot say without uncertainty that a slow emulsion will have good resolution.

Absolutely true! Years ago I tried to do "8x10" style photography with a 35mm camera and ultra high resolution document film. To beat the contrast I used severely pulled development and massively increased exposure to compensate the speed loss. Net result was grainless but unsharp negatives. Why? The enormous exposure caused enough light scattering and halation within the emulsion to kill edge definition!