Exposure latitude color neg. vs. color chrome film.greenspun.com : LUSENET : Large format photography : One Thread
Has anyone ever performed testing to objectively demonstrate how much more exposure latitude negative film has vs. chrome film? If you read published data, it suggests on average 1-2 stops more. But yet, I still hear boast about 3-4 extra stops. Maybe its a specific type of color neg film that exceeds in this area? Unfortunately, film makers don't test films for this and rarely publish any "real world" test data on this issue.
-- Bill Glickman (firstname.lastname@example.org), November 24, 2001
This doesn't answer your question about existing test results, but you might try this: Make four exposures of the same subject on the same roll of film (save the 4x5 sheets for something else), take one at correct exposure, then one each +1, +2 and +3 stops. Take it to a quality lab and tell them what you did and ask them to print four prints that look as close to the same as possible. They'll be able to do it with little effort. They'd also probably get a good print, albeit slightly less contrasty, from a -1 exposure. Slide film, on the other hand. . .Well, +1 or +1.5 over and you can usually transfer it straight to the dumpster.
-- Todd Caudle (email@example.com), November 24, 2001.
In the October 1994 issues of "Camera & Darkroom," Joe Englander describes what appears to be a very elegant procedure for determining a personal exposure index that correlates to an evaluation of a film's usable range by contacting printing a 21-step density tablet. The article, entitled "Therapy for Exposure Anxiety," is available as a PDF file on Englander's site:
I'm doing architectural photography and typically exposing Fuji transparency film (Astia, Provia, RTPII), as well as negative film (NPS, NPL), for each shot, and so am extremely interested in this question as well. In order to perform this test on these five films, I've just had just had my Zone VI/Pentax digital spotmeter calibrated by Richard Ritter, and purchased both both the Wallace Expo Disc and the 21-step tablet that Englander recommends. I'll report back when I have the results in front of me.
-- Christopher Campbell (firstname.lastname@example.org), November 24, 2001.
Christopher is on the right empirical approach but there is another way of looking at the problem.
While a color negative may have more dynamic range (d.r.), in general we don't look at color negatives, we look at prints made from color negatives or we look at lithographic or even inkjet or dyesub reproductions of the orginal image. So you really have to consider what the d.r. of the final reproduction step is. For virtually all commercial (mass distribution) lithoigraphy (magazines, posters, brochures, etc) the dynamic range is equivalent to about 4 stops, no matter what the original medium (color neg, transparency, digital) is. Most color prints have a slightly larger d.r. than that, but not by much.
Of course it always helps to have more detail up into the highlights and down into the deep shadows, but making use of that additional range in a way that doesn't look faked is tricky.
-- Ellis Vener Photography (email@example.com), November 24, 2001.
Chris, the pdf file was too blurry to read? Anyway, I tried to devise a test once to accomplish this... I set up white towels, grey towels and black towels. I used towels so I could evaluate how much texture I could see in the film. I started the with white towels with a bright light on them... the light shined downward to the other white towels, so that each towel droped one stop. And of course the greys droped and then the black based on the position of the lights... Considering white to black will give you about 5 stops, you only have to manipulate the lighting to gain the additional 4 stops. AFter hours of setting this up and shooing, I patiently awaited the film... then I ran into my next problem... the chrome film was easy to read, as expected about 4.5 - 5 stops. But I was unsure how to read the negs? I was searching for texture in the negs through a loupe on a light box, but I found it too hard to read... I thought about scanning it, but that would intrdouce a new variable. Was this test sensible?
I later found that a white porcelain piece of art will yield about 2 extra stops for white and black flocking paper (used to line the inside of cameras) absorbed two more stops vs. black card. So I felt between these two, I might have a way to shoot objects all in a row with even lighting, allowing the subjects reflectivity to produce the desired reflected light to the film. I was hoping someone with a bit more experience than my home brew methods has done this already? How about peoples experience using color neg film?
Ellis, as per your comments on the final product being the bottleneck... Even if you use 10 stop film and print on 4 stop paper, digitaly, you simply compress the values to fit within 4 stops. But the beauty is, no loss of detail. If I can't record it on film, forget it, even digitaly its a battle... and landscapes we have no control over the lighting....sometimes I don't have weeks to ride out the lighting so its just perfect...
-- Bill Glickman (firstname.lastname@example.org), November 25, 2001.
In answer to Bill's 4 stop window suggestion:
In the good old, bad old days when we shot a piece of film and sent it off to a client who got a pre-press expert to scan and prepare the image for publication we all swore by the four-stop-window because it aleviated the need for compression or expansion.
With the level of scanners available for personal use by modern hybrid workers and the pre-press skills (or lack of) of the practitioners I doubt very much that compression or expansion has become any more desirable.
Somebody more qualified than me will doubtlessly have another perspective on this. However, I coninue to shoot with the final four-stop-window in mind and it works to the satisfaction of my publisher clients and my phot-display clients. And it allows me to keep the work-flow simple.
Cheers ... WG
-- Walter Glover (email@example.com), November 25, 2001.
Ctein in “Post Exposures” claims color negative film has an absolute range of 10 or more stops ( page 80 ). The dynamic range is usually two stops less then the absolute range. I can rely on some detail in Zone II and Zone IX on the color negative film I am using now. This of course depends on the heal and shoulder of the characteristic curve of the film. Films with more pronounced heals or shoulders will have less dynamic range.
Why your negatives showed no detail at all might be do to an exposure error or a processing error. Did they appear thick? Did they appear thin? Was there a presence of an orange mask. I once sent some 35mm color negs for processing and the lab developed them in B&W chemistry? They had a deep blue tint to them.
I believe the best way to characterize your films is to take the time and expense to construct a characteristic curve of each film. The information in embedded in these curve is amazing. “The Negative” outlines a method for doing so, but I can provide you with additional tips to make it more accurate and easier. Once you have a curve you can easily and accurately extrapolate the dynamic range. Overlaying curves from different films will clearly highlight the differences.
Hope this helps.
-- Stephen Willard (firstname.lastname@example.org), November 25, 2001.
Steve, thank you, you are still the color negative guru!
> I can rely on some detail in Zone II and Zone IX on the color negative film I am using now.
OK, so with this film, you estimate 7 stops you can record detail, is this correct? I find this reasonable based on my shaky tests. What film is it? I have been testing Kodak Porta VS160.
> Why your negatives showed no detail at all might be do to an exposure error or a processing error. Did they appear thick? Did they appear thin? Was there a presence of an orange mask.
Yes,they clearly had an orange cast...but I just had a hard time reading the dark areas on a light box, I think I started seeing things? And yes, very dense.. I could easily make out 5 stops, but then I kept second guessing myself, hence the reason I was looking for an easier solution, and I don't have a dark room.
> I believe the best way to characterize your films is to take the time and expense to construct a characteristic curve of each film.
What information does the curve tell you that is useful in shooting? My main goal was to get a more accurate feel for the number of stops of lattitude vs. chrome film. The neg film does not scan as well as chrome film, and from what I determined from scanning, I don't see a big difference in exposure lattitude, at best I see 1.5 stops, not the extra 4 stops I was hoping for. If that is the case, I doubt I will continue to use it as it is much harder to get the colors accurate in Photoshop.
-- Bill Glickman (email@example.com), November 25, 2001.