PMK negative density : LUSENET : B&W Photo - Film & Processing : One Thread

I've posted this question on, too, if this seems like deja vu, but I've been struggling with what a PMK negative is supposed to look like. Hutchings says "murky, low contrast, seemingly unprintable." Is that another way of saying overexposed?

Conventional wisdom says to use the minimum exposure that gives adequate shadow detail. Hutchings says to place highlights on the highest values (after you've already added 2/3 of a stop with your ISO). Is PMK different? Am I supposed to "overexpose" it? I've about quadrupled my print times with these denser negatives and am picking up quite a bit of grain, too. Is this normal? I'm already liking this stuff, but I sure need some help getting it dialed in.

-- Brian Hinther (, May 15, 2000


Barring any strict densitometric readings, and adjusting my eye to the yellow/green stain, my best (printable) PMK negs seem to look about the same as any other neg, with the exception that the highlights seem to have more detail when looking at the negative.

As for the ISO thing, I've noticed that PMK generally wants about 1/3 stop more than most developers I've used, but otherwise it behaves pretty normal. For example, PMK with Technical Pan gives me ISO16, as opposed to Technidol which gives me ISO25, and apart from the difference in highlights, the two look pretty similar when printed. But that's all just my experience.

-- shawn gibson (, May 16, 2000.

ps: don't rely on ANYBODY'S ISO as a rule; use Adams' ISO test or something similar. Meter something flat at Zone 1, bracket your shots 1/3 stop for several stops, and develop your film normally. The first frame to give you usable density (essentially) is what you should rate that film/developer combination at.

-- shawn (, May 16, 2000.

I rate most of my films at half their ISO rating (though T-Max 400 is an exception). I think the description given above is correct-- negatives should look almost normal, except that the highlight values are not opaque as they often are when a negative is developed in a conventional developer. You definitely need to test with your own equipment and processing methods to get the right EI.

-- Ed Buffaloe (, May 16, 2000.

See Basic Techniques of Photography Book 2 by John P. Schaefer, available from Amazon & elsewhere, for a terrific explanation of how to calibrate your developing and determine effective density using only test strips. Works for me.

-- Don Karon (, May 16, 2000.

My understanding has been that the 'silver image part' of a pyro neg should look murky i.e., like it was underdeveloped. This is because the stain adds density in proportion to the silver. So, the negative may look normal (i.e., when you assess the silver plus stain density) but the silver image itself should look murky and low in contrast. DJ

-- N Dhananjay (, May 16, 2000.

The eye is most sensitive to yellow light. Yellow filters blue. Photo papers are most sensitive to blue. So, a negative can have a lot of yellow dye (stain), we look through it and it looks like the density is low. The photo paper looks through it and it looks dense.

This is the "murky, low contrast, unprintiable" appearance of pyro developed negatives. I suspect if you looked at the negative through a blue filter, it would look more to they eye as the paper sees it. But they eye is not very sensitive to blue light.

-- Charlie Strack (, May 19, 2000.

The only way to determine ISO (actually EI) is to test for the exposure that will produce 0.1>B+F. If you are using PMK, then you must use a color densitometer and use the blue channel. I have measured most films, and for what it's worth this is what I got. Pan- F, EI:32; FP-4+ (and Arista 125) EI:80; HP-5+ (Arista 400) EI:200; Delta 100, EI:100 (!); Delta 400 EI:250; TMX EI:64; TMY EI:320; +X EI:80 (has a weird blue B+F.) I hope some of you will find this information useful. BTW, I used a CALIBRATED Zone VI digital spot meter. Z6 has a surprisingly lax atitufe on calibration.

-- Michael D Fraser (, May 30, 2000.

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