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Metering for B/W Films
There are many discussions on the internet for using lightmeters, either reflective or incident. Much of it for digital or color reversal films.
When it comes down to B/W films, methods such as the zone system or BTZS are mentioned. How do the visitors here like to use their lightmeters for exposing B/W films for enlarging or contacts in the wet darkroom? |
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Metering for B/W Films
On 3/5/2012 17:01 PM, Darkroom User wrote:
There are many discussions on the internet for using lightmeters, either reflective or incident. Much of it for digital or color reversal films. When it comes down to B/W films, methods such as the zone system or BTZS are mentioned. How do the visitors here like to use their lightmeters for exposing B/W films for enlarging or contacts in the wet darkroom? I don't. I have an old spot-type print analyzer that I use to get dynamic range and then time settings. It would seem to me that a light meter, unless it is a spot meter, is not going to be all that useful in the darkroom. -- Francis A. Miniter Mesure is Medicine þauh þou muche ȝeor[n]e. Al nis not good to þe gost þat þe bodi lykeþ, Ne lyflode to þe licam þat leof is to þe soule. William Langland, The Vision of Piers Plowman Passus I, lines 33 - 35 |
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Metering for B/W Films
Francis A. Miniter wrote:
I don't. I have an old spot-type print analyzer that I use to get dynamic range and then time settings. It would seem to me that a light meter, unless it is a spot meter, is not going to be all that useful in the darkroom. Another approach which worked well in the past when no one worried about being able to buy another box of paper or a bottle of developer, was a test print. Often I would tear a piece of paper into quarters, or use a sheet of paper that had been crumpled, bent, torn, etc. I would pick the area of the print I thought was most important and print that. Once it was in the fixer, I'd turn a light on and look. I had a very bright light over the sink, so I could judge a print as I was washing it. The zone system and others like it are camera systems to produce a negative that has a tonal range and print exposure like every other negative you produce, making printing easier. It is interesting to see the prints made by and for various photographers over the years from the same negative, for example Ansel Adams. Geoff. -- Geoffrey S. Mendelson, N3OWJ/4X1GM My high blood pressure medicine reduces my midichlorian count. :-( |
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Metering for B/W Films
When it comes down to B/W films, methods such as the zone system or BTZS
are mentioned. How do the visitors here like to use their lightmeters for exposing B/W films for enlarging or contacts in the wet darkroom? As a coarse approximation, I meter the darkest shadows where I want some detail, meter the bright spots (avoiding specular reflections), split the difference. If the difference is too broad, you'll exceed the range of the film (unless you have the ability to adjust the processing per frame, i.e. sheet film). If the whole scene is very dim, you may end up "promoting" it all to appear brighter than it was. Etc. Bottom line, the "correct" exposure is the one that gives you the result you wanted. It's worth reading the Ansel Adams and Phil Davis books, even if you don't intend to do the whole calibrated process thing. There's a fair amount of useful thumb rule stuff in there, and they can help you cement the idea of shifting things up and down the scale to get what you want. De |
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I mentioned the wet darkroom, because that is how I make my prints. |
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Metering for B/W Films
On 3/6/2012 12:32 PM, Darkroom User wrote:
'Francis A. Miniter[_2_ Wrote: ;945476']On 3/5/2012 17:01 PM, Darkroom User wrote:- There are many discussions on the internet for using lightmeters, either reflective or incident. Much of it for digital or color reversal films. When it comes down to B/W films, methods such as the zone system or BTZS are mentioned. How do the visitors here like to use their lightmeters for exposing B/W films for enlarging or contacts in the wet darkroom? - I don't. I have an old spot-type print analyzer that I use to get dynamic range and then time settings. It would seem to me that a light meter, unless it is a spot meter, is not going to be all that useful in the darkroom. -- Francis A. Miniter I should have made my post more clear. I meant exposing the films in camera. I mentioned the wet darkroom, because that is how I make my prints. Ah. When shooting, I prefer a spot meter, or, if I am using a camera with multiple function metering, I almost always choose the spot option. I prefer to do my own "weighting" of the scene, especially since I want to make sure that the object of the scene, whether on center or off, is properly metered, whatever else about the rest of the scene. I don't overtly use the zone system, but I do try to compensate for overly wide or overly narrow dynamic light ranges. By the way, I rarely use color reversal films. Most of my shooting is B&W, with about a third to 40% color negative film. -- Francis A. Miniter Mesure is Medicine þauh þou muche ȝeor[n]e. Al nis not good to þe gost þat þe bodi lykeþ, Ne lyflode to þe licam þat leof is to þe soule. William Langland, The Vision of Piers Plowman Passus I, lines 33 - 35 |
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Metering for B/W Films
Darkroom User wrote:
There are many discussions on the internet for using lightmeters, either reflective or incident. Much of it for digital or color reversal films. When it comes down to B/W films, methods such as the zone system or BTZS are mentioned. How do the visitors here like to use their lightmeters for exposing B/W films for enlarging or contacts in the wet darkroom? I have two lightmeters. One is a Pentax digital spot meter modified by Zone VI. The other is a Luna-Pro-F that is either a reflective meter or an incident light meter, depending on whether the white dome is over the cell or not. It also works as a flash meter. Normally, I shoot outdoors and use the spot meter, using the Zone System. I carry the Luna-Pro as well as a backup. This saved me once when I forgot to change the battery in the Zone VI, and it went dead on me. When shooting with electronic flash, I use the Luna-Pro-F in flash mode, usually incident readings. It is important to know what the meters are doing, especially if you have more than one, or you will drive yourself crazy. They will seldom read the same, and the differences are more than just the different sensitivity to the illumination. That could be simply calibrated for. They are also different to different colors, and unless you make a very careful test, this is impossible to calibrate for. What I did (once: it is a pain to do it multiple times), was wet up an 18% gray card and illuminated it from a blue sky. The illumination was not changing during the test. The gray card was the same color from test-to-test, and was as good a standard as any. Especially since I normally shoot in black and white. For that I could get a bunch of meters to read the same. One camera meter had a CdS cell, and the rest were silicon, but with different color response curves. The Zone VI is allegedly calibrated so the film sees what the eye sees, or something like that. But that would depend on what kind of film was used, and I suppose Fred Picker used either Tri-X 4164 or maybe Plus-X 4147. Since I shoot TMax, it will have a different curve. I doubt this matters very much because the saturation of colors around here is not very great. At first I was surprised that the Luna-Pro gave different readings for incident light and for reflected light from the gray card. This was when reading incident light with the sun in the sky. I then figured out how to do the measurement when the meter and the gray card could not see the sun. Then the meter read the same incident and reflected. Wow! The subtleties will get you if you have more than one meter. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 09:35:01 up 19:16, 4 users, load average: 4.65, 4.74, 4.72 |
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Metering for B/W Films
"Jean-David Beyer" wrote in message ... Darkroom User wrote: There are many discussions on the internet for using lightmeters, either reflective or incident. Much of it for digital or color reversal films. When it comes down to B/W films, methods such as the zone system or BTZS are mentioned. How do the visitors here like to use their lightmeters for exposing B/W films for enlarging or contacts in the wet darkroom? I have two lightmeters. One is a Pentax digital spot meter modified by Zone VI. The other is a Luna-Pro-F that is either a reflective meter or an incident light meter, depending on whether the white dome is over the cell or not. It also works as a flash meter. Normally, I shoot outdoors and use the spot meter, using the Zone System. I carry the Luna-Pro as well as a backup. This saved me once when I forgot to change the battery in the Zone VI, and it went dead on me. When shooting with electronic flash, I use the Luna-Pro-F in flash mode, usually incident readings. It is important to know what the meters are doing, especially if you have more than one, or you will drive yourself crazy. They will seldom read the same, and the differences are more than just the different sensitivity to the illumination. That could be simply calibrated for. They are also different to different colors, and unless you make a very careful test, this is impossible to calibrate for. What I did (once: it is a pain to do it multiple times), was wet up an 18% gray card and illuminated it from a blue sky. The illumination was not changing during the test. The gray card was the same color from test-to-test, and was as good a standard as any. Especially since I normally shoot in black and white. For that I could get a bunch of meters to read the same. One camera meter had a CdS cell, and the rest were silicon, but with different color response curves. The Zone VI is allegedly calibrated so the film sees what the eye sees, or something like that. But that would depend on what kind of film was used, and I suppose Fred Picker used either Tri-X 4164 or maybe Plus-X 4147. Since I shoot TMax, it will have a different curve. I doubt this matters very much because the saturation of colors around here is not very great. At first I was surprised that the Luna-Pro gave different readings for incident light and for reflected light from the gray card. This was when reading incident light with the sun in the sky. I then figured out how to do the measurement when the meter and the gray card could not see the sun. Then the meter read the same incident and reflected. Wow! The subtleties will get you if you have more than one meter. I think the key is the same as in electronics and elsewhere, namely understand what your instruments are actually measuring. From the 1920s through the 1950s a long series of research reports was published by Loyd A. Jones, along with some others, of Kodak Research Laboratories, on the tone rendition of film and paper. Much of this was directed toward black and white but has applications even for color. One of the results of this research was the speed system adopted by the ASA in the mid 1940s. Among other things Jones wanted to find out the _minimum_ exposure that would result in an _excellent_ print. The idea was that film produced the sharpest images and least grain with minimal exposure. Film is better now but this still is true. After extensive testing on actual scenes and blind testing of prints from the negatives, Jones found a definite speed point for minimum exposure but also found that the overexposure latitude was very great. That is, once the film gets enough exposure to make a good print further exposure does not change the tone rendition over a range of many stops. The Kodak Speed System adopted by the ASA, and indeed all subsequent speed systems, assume a fixed gamma or contrast index for the negatives. The idea is that the scene brightnesses would be accurately recorded so that print contrast would be determined by the contast of the paper. The development of the Zone System essentially reverses this approach in that it adjusts the contrast of the negative to fit a fixed contrast printing medium, the idea is to insure fitting all important scene brightness data on the negative. Either system works. One reason Ansel Adams promoted the Zone System is that he had gotten poor negatives for some important pictures due to under-exposure. While the latitude of _overexposure_ of most film is very great, the latitude for _underexposure_ is no more than one stop and maybe less. Assuming one has printable negatives made by any exposure system one encounters another problem: namely the tone range of paper prints to be illuminated by reflected light, is far less than either the range of brightness in the original scene or the range on the negative. However, the eye still expects to see something like the original tone range, at least in the mid-tones. If overall contrast is lowered to present a high-contrast (wide tone range) scene on the print the result will be seen by the eye to be grayed out, especially if the scene is something fairly familiar. The approach that has developed over time is the compress the highlights and shadows to some degree while leaving the mid-tones alone. In chemical photograpy this is done partly by choosing paper with an S shaped charistic, or the use of masking, or simply manual burning and dodging. No adjustment of exposure and development will replace this. The best one can expect of a light meter is that it will help fit the scene brightness range into the range that can be recorded on the film. The main difference between a reflected light meter and an incident light meter is that the incident meter can not measure subject brightness range. It _can_ measure lighting ratio directly, which is often helpful where lighting is under control. A reflected light meter can measure subject brightness range. Both types of meters are useful but again one must understand what they are measuring in terms of what will be recorded on the film. I am glad to see a few of us still follow this news group. -- -- Richard Knoppow Los Angeles WB6KBL |
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#10
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Metering for B/W Films
"Darkroom User" wrote in message news hanks Richard, but I am still not sure whether to rely on Incident or reflective measurements. How do you use your lightmeter for outdoor photography? -- Darkroom User Personally, I use a combination meter usually an old Gossen or a Sekonik Studio meter similar to the old Norwood. These give a choice of incident or reflected readings. I can write a long treatice on the difference but I've also shot a lot of color slides using the TTL meter on a Nikon F and very few were badly exposed. This is, of course, a reflected light meter. I think you can get good results with either provided you understand what its measuring. In principle, the incident meter should give you a more exact rendition of what the scene looks like but that may not be what you want. It can not measure _subject_ brightness and contrast where the reflected light meter can. OTOH, the reflected light meter will need some help from you in deciding how bright the objects in the picture are to be in the print. I also have some questions about the actual utility of the hemispherical light integrator found on many meters. Supposing one is photographing a back-lighted scene; does one want the exposure to be for the relatively shadowy areas for the very bright highlights? If the meter is used as directed, that is held in the scene and pointed toward the camera, the sensor will not see the light coming from behind and result in a much greater exposure that will wash out the backlighted highlights. If its pointed at the source of light it will expose the highlights correctly but blank out the shadows. You have to decide what you want to show up on the film. What can be difficult is that in life the eye is making constant rapid adjustments for light level which can fool us about just how great they are. -- Richard Knoppow Los Angeles WB6KBL |
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