film exposure range - how many stops?

[lernie_ang]

i've dutifully searched as many threads i could about exposure range,

but i found none that answered this question that i am asking:

 

what, indeed, is the amount of f/stops that black and white, and/or

color print film (generally speaking) can record?

 

and another thing, if i may: this whole exposure latitude is driving

me nuts. now i know what exposure latitude is. but what i dont get is

how there is a fixed range for a particular film, when i know

exposure latitude is the excess f/stop range between the film

exposure range AGAINST the scene brightness range. of course, if

indeed b&w and color print film have a 'standard' exposure range,

like say maybe 5 stops, then i can understand if manufacturers say

our film has an exposure latitude of 1 3/4 to 2 stops. that would

probably mean that the film has an exposure range of 7 stops, for

example.

 

thanks for any help.

 

 

lernie.

[Andrew in Austin]

<p>Keep in mind that can be recorded on film and what is pleasing when viewing the print aren't always the same. In other words, after you've exposed the negative, you still have the second step of exposing photographic paper.</p>

 

<p>My guess is even if you over expose a color negative by one or two stops, you'll still have 7 stops recorded on film. Of which, 4 to 5 stops show up as well exposed when the print is made on an automated minilab printer.</p>

 

<p>On the other hand, if you <u>under</u> expose a color negative, then the exposure may actually suffer a decrease with regards tp the useable dynamic range recorded on the neg.</p>

 

<p>With black and white, I can do my own printing. Consequently, with a traditional optical enlarger one has the option expose a little wider dynamic range onto the final print by either burning or dodging.</p>

 

<p>This last bit of info may be technically obsolete, because there are digital printers that use CRT's to transfer the image from the negative to the print after doing a digital scan. In this case, dodging should be achievable by manipulating the scanned image.</p>

[moe_p]

Projected slides have a maximum latitude of 8 or 9 stops. Perhaps 400:1

Black and White print paper almost 7 stops or 100:1

Colour magazine paper 3 to 4 stops. 20:1 according to Greenspun.

 

How does this help you? Are you trying to estimate the contrast in a scene as in the zone system?

[lernie_ang]

thank you for the response. i'm actually not going to print any of the shots into paper, at least not readily. i plan to scan them directly to avoid contrast differences in papers (and save money and time).

 

what i'm actually trying to do is know how much exposure range i have in a particular film so that i can make sure i can take multiple exposures without losing detail on both the dark and light areas. if the scene has a 9 stop range, and suppose that my film has only 5-stops that it can record at any give time without blowing up, then it will tell me how to progress up or down the f/stops so i can capture, in multiple frames, the whole scene brightness.

 

again, thanks.

 

 

lernie.

[peter_witkop]

Generally it all depends on the film, all film is made with differant purposes in mind, which effects the latitude. Most of the time with color films I'll assume I've got about 5 stops between the darkest areas I want to have good detail in, and the lightest. There will often be another stop or two on either end of that were I haven't got either pure black or white and some detail exists, but I try to make sure that everything I'm concered about is in those middle 5 (and will look descent were it falls in that middle 5, which is a differant discussion all together). That said, you're really best off to test for yourself to see exactly what you get with a particular film and what's accpetable to you. Also in B&W, it's kind of a hard question to anwser, with normal development you can get about the same 5 stops of good detail, but if you've done enough testing and played with your development enough, you can expand it out to around 10 stops (you do make some compromises though), this is what the zone system in B&W is all about. Incidentally, you can use the zone system, minus the development controls on color films. The only major differance (other than the lack of dev. control) is with chrom (slide) film I base my exposures around the high, rather than low values. Sorry for rambling quit so long, hope it helps

 

Peter

[James G. Dainis]

It's easy enough to determine by your own tests. Set up a gray card and take a shot at the normal exposrue. Open up one stop and take anther shot, open up another stop and take another shot, etc. Then close down one stop from the normal gray card exposure and take another shot, close down another stop and take another shot, etc. Examine the film. You will see a one stop difference in darkness in the frames of the over exposed shots until there is no difference - just pure black. You will see a one stop difference in the underexposed shots until there is no difference - just clear film base. That is the film latitude. With most black and white films there will be a difference in four stops over and four stops under - nine zones of latitude.