Rate Lower for better saturation?

[frank_gary]

<p>I just got some slides back and it was suggested that I rate my slide film at a 1/3 slower to improve saturation. This was recommended for both velvia and Fuji provia 100F. I'm a bit confused about this. It seems to be that as exposure goes up (which I'm doing by rating lower right?) then we are mixing white into the pure color and therefore causing the saturation will become lower. Could someone explain how increasing exposure increases saturation because it just doesn't seem right to me. Thanks</p>

[larrydressler]

<p>Positive and negative... when you over expose a little it allows the shadows to be a little brighter and bring out the color of them plus the highlights get a tad more light but hopefully you don't wash them out.</p>

<p> Personalty I shoot box speed if I don't have a spot meter and hope for the best.</p>

 

[SteveH]

<p>I agree with you. My understanding is that you should UNDERexpose about 1/3 stop for improved saturation. You could test this yourself by bracketing exposures and see which you like best.</p>

[Alan Marcus]

<p>First, consider that film manufacturers spend considerable time and effort to control film speed (ISO). It is naive to think you can do better. Stated in other words, the best results obtainable occur when film is correctly exposed.<br /> <br /> That been said, it may be necessary to re-rate films. Should your light meter consistently over or under expose, adjustment of the ISO setting is a countermeasure. The same applies to equipment idiosyncrasies such as shutter or processing consistency error.<br /> <br /> Negative films have considerable latitude. A key point when dealing with negative films, we do not hold up the negative and say, "that's aunt Bertha, doesn't she look fantastic!" We print negative film. Printing is tantamount to retaking the picture. During the printing cycle, we are granted the opportunity to compensate for exposure errors made during the initial exposure. Thus the printing procedure stretches the latitude of the negative film. Nevertheless, exposure latitude decreases as subject contrast, film contrast or development contrast increases. Negative films have greater latitude in overexposure direction than in the underexposed direction.<br /> <br /> Reversal (slide) films have little latitude in either direction. Underexposure of slide materials yield an increase in density that results in a loss of contrast and detail. Professionals who know that their reversal film are to be viewed as prints or in books by lithography, often deliberately underexpose to gain highlight detail. They are depending on the printing / reproducing procedure to correct any induced density errors. Slides viewed by projection are unlikely to benefit by purposeful underexposure.<br /> <br /> For deliberate underexposure, the light meter is fed an elevated ISO value. This forces a faster shutter speed or a reduced aperture diameter or combination. Perhaps it is better to manual close down the aperture. When dealing with aperture, f/number manipulation can be confusing. As an example; if the meter reading callas for f/5.6 and you stop down 1/3 f/stop, the setting becomes f/6.3. Likewise if the film speed is ISO 100 and you compensate upwards<br />1/3 f/stop, the imputed ISO becomes 125.</p>

<p>In conclusion, I suggest the usual adjustment you apply be 1/3 f/stop with the maximum adjustment being 1/2 stop. Nobody says this stuff is easy.</p>

[larrydressler]

<p>Oh and if you shoot with many different cameras as I do remember ISO stands for International Standards Organization. So when they say 400 it means 400 but you also have to look a little different when it is B&W film as those standards are set with a developer of the manufactures choice.... E6 and C41 are standard..... Many old habits carried over to color... Digital has different standards with the ISO. So comparing Film to Digital is apples and Lemons if you want to do that.</p>

<p> Last time I checked Kodak was still using D-76 even with their T-grain films as their standard but it may now be Xtol. AGFA used Rodinol Ilford uses ID-11....<br>

ISO is a Standard... and now the thing is Meters also have standards.... but all are not the same nor is the battery that has been in your camera after 3 weeks.... :-)</p>

<p>To each their own.</p>

[john_shriver]

<p>One quibble -- ISO is (in English) the "International Organization for Standardization". Note that I said "in English", which is the core of the issue. ISO is not an acronym for the name of the organization in ANY language, as that would be favoring one language over another. Many Europeans, especially the French (who often think their language is the one that should be favored) would not be comfortable favoring English.</p>

 

[larrydressler]

<p>Point taken so we have no standard even on the name. :-)</p>

[Alan Marcus]

<p>ISO<br />International Organization for Standardization (English)<br>

Organisation Internationale de normalization (French)<br>

Founded February 1947 headquarters Geneva, Switzerland.</p>

[sfcole]

<p>I think the common wisdom of slight underexposure for saturation is now obsolete. It worked for the projection of slides, but it does not now work when scanning because it produces noisy scans, often with funky colors. I've found this with various transparency films, and now err on the side of slight OVER exposure if not box speed.<br>

Also, in spite of the supposed latitude of color negative film, my tests have told me that even slight overexposure can blow out subtle skin texture for portraits.</p>

[matt_brown6]

<p>I think the effect of rating your film lower varies depending on your film. I've never tried down-rating slide film, but with such little latitude, I would say that the MAXIMUM you'd want to go would be 1/3 lower.</p>

<p>I shoot a lot of color film, and my method for down-rating depends on what stock I'm shooting. My favorite film is Fuji Pro 160S, and I find that if I rate at 160, I will come out with slightly underexposed negatives. But if I rate at 100, my negatives are properly exposed and retain beautiful color saturation in the shadows. Not to mention that grain is virtually non-existent. Typically, though, I will rate Fuji Pro 400H at box speed or at 320ASA and come out with perfect negatives. I tried, for a few rolls, to expose 400H at 200, but saw a huge magenta color-shift when I got into the darkroom.</p>

<p>On the rare occasion that I shoot Kodak, I always rate at box speed. Anything above or below that resulted in negatives that shifted yellow.</p>

<p>Anyway, happy shooting!</p>

[ted_marcus1]

<p>In the old days, when Kodachrome and [non-avian] dinosaurs ruled the Earth, it was common practice to slightly underexpose Kodachrome to get more saturated color. (Nobody knew then that the increased density would make Kodachrome even more difficult to scan.) More saturated films made that practice [and Kodachrome] obsolete. "Expose for the highlights," and if you need more saturation you can always scan the slide and increase the saturation in post-processing.</p>

[photo5]

<p>Ted said what I was going to say. I used to rate K64 at ei80, and K25 at ei40. That made for great slides for projection, but boy are they difficult to scan!! I recently shot a test roll of Ektachrome through a Nikon FE2 I bought recently and rated it at box speed. I bracketed a few shots and decided that the FE2 meter is such that I will rate the film at ei125 instead of 100 next time. It's all about testing your particular meter and just shooting a test roll and see how it turns out.<br>

tl;dr - Under exposed slides are hard to scan, but look great for projection. What is your final usage?</p>

[larrydressler]

<p>Kodachrome is dead... Face it soon Velvia 50 will be too. It died once.... I know 1 thing in this life.. If you don't have control of the development and printing/scanning of your fil then you cand judge anything because after you have exposed it it is no longer your's.</p>