Color Transparency Exposure

[Keith S. Walklet]

Frank's method is similar to my own approach, passed along years ago by Pat Ohara. Using QuickLoad film, make three exposures at the same settings. Each of the three film sleeves is marked the same way, to indicate exposure, filtering, compostion. On a day where I create twelve unique images, that means 36 exposures.

When I get home I log the exposures in the order that I took them, numbering each in sequence. (Some folks number and letter such as #121-A, #121-B, #121-C but I've found just sequential numbering works just as well). Then I take one from each set of three frames (say frame A) to the lab to be processed normally.

Since some compositions are only slight variations on a theme, the lab needs to "twin check" the film with a pair of identical numbers (one on the film, one on the sleeve) in order to keep the film organized. That means in addition to my film, I get my sleeves back so I can match my notes to a particular image.

I then evaluate the exposed film. If it is off, I make an adjustment to the processing instructions for that image and send in the second (frame B) of the set. And so on.

If I get it right the first time, I have three well-exposed duplicate images. If I miss on the first frame, I have two more chances to get it right.

This is one of the real advantages to using single pieces of film, vs. a roll, and the reason I typically use the Quikloads (which are heavier) instead of loading my own film.

[Jim Rice]

Actually I'm throwing in with Ronald here, at least with regards to color tranny materials. An incident meter is the cheap/dirty WORKS way to go. I use a 30 year old Sekonic L-28 c2 that i bought new long long ago. I also rate Velvia at ei. 40.

[Jim Rice]

And congratulations, Frank.

[Henry Ambrose]

Bob, having your shutter checked is a good idea if you think it is off compared to a "known good" camera.

But more important -- test your outfit!

Go out with your 4X5 camera and 150mm Nikkor, pick an average kind of scene that is stable light wise, meter as usual, expose one sheet as metered with the meter set at manufacturers box film speed, then add one third more light to each succeeding sheet. For 100 speed film this would give the following settings on your meter for each shot: 100, 80, 64, 50, 40, 32. You'll end up with six sheets of film that will tell you most all you need to know about your meter, your camera, the film you use and the way you meter.

And for what its worth I've never found a transparency film that looks right without a bit more exposure than the box says. For me Velvia is 32-40, Provia is 64-80. You should test to get your own numbers.

[Michael S. Briggs]

What were the lighting conditions when you used f45 at a few seconds, and f22 at 1/10 s?

You can use the "Sunny 16" rule as a backup "sanity check". Somewhere on the web you will find suggested correction factors for various conditions, such as light overcast, heavy overcast, etc. Using these, if the extended Sunny 16 rule gives an exposure much different from your metering, then you are probably making a blunder.

You might consider using color negative film instead of transparency film. The exposure lattitude is much larger. This will help with small mistakes in exposure and also get better photos of subjects with a wide brightness range.

It is possible that the problem is the accuracy of the shutter speeds, but I think it unlikely. Obviously the few seconds exposure wasn't controlled by the shutter. Modern Copals are usually quite accurate. Finding a shutter to be slow at 1/125 or faster with the Calumet shutter tester is a red herring for two reasons. First, such fast shutter speeds are virtually never used in LF photography. Second, the shutter is calibrated in effective speed, and, most users of the Calumet shutter tester are probably measuring total opening time. Used in the obvious manner, the Calumet shutter testing starts timing as soon as the blades open. When the blades first open, the aperture is smaller than that set by the aperture diaphragm, so the total opening time and the effective time differ. This only matters for the fastest speeds, for which the travel time of the blades is important. This has been discussed here before.

Unless your desired depth-of-field requires f45, I suggest using wider apertures. Your image from a modern Nikkor will definitely be softer at f45 than at wider apertures because of diffraction.

[Don Miller]

It's probably something simple like bellows factor, big rise/ shift or similiar. Try testing with a simple distant subject. Have you read the exposure articles on this site? If you can expose velvia correctly with your other cameras (using the same meter) there's nothing much different with LF except what I mentioned above.

Most of us want to take the new camera out into the wilderness without testing/learning first. When that doesn't work well one ends up in the back yard doing simple tests.

Don

[Jim Becia]

Bob,

As a 508 owner also, I can tell you that I have to rate my Velvia at 32 and my E100VS at 64 to get the exposures that I consider correct. It seems that the meter is calibrated differently. Oh, I have a friend with one also, and he, likewise, has to rate his film at these numbers to get a proper exposure. Jim

[Keith S. Walklet]

Another factor in the film evaluation equation is whether or not you have a proper light table. Ideally this should be rated at 5000 K.

Mind you, illumination often varies across the surface of the light table depending on where the bulbs are. For critical evaluation and consistency, you should identify the sweet spot on your table and do your evaluations there.

[tim o'brien]

After reading all these great answers, my question Bob is... What do you mean under-exposed? Is the tranny dark or light in respect to what you expect?

tim in san jose

[Frank Petronio]

Another meatball way that I use for color (and for B&W portraits) is to meter my hand. The inside of my palm is Zone 6.5, the tanned backside is Zone 5.5. I'm a dark Italian - your mileage may vary. Get's you in the ball park and is good when the highlights go specular (like water reflections) and are just going to blow heck outta the highlights out anyway.

Ansel is spinning in his grave...