View Full Version : OT- Hey Dave Opincorne(sp?)
02-24-2005, 08:21 PM
Hey, so what is Zoning actually in photography? You mentioned to get in contact with you when I was ready for it.
02-25-2005, 12:19 AM
Well zoning has to do with breathing in to much fix, but that wasn't what I was refering to. The Zone System was what I was refering to. If you're just starting you should wait to refine your knowlege of B&W materials and processes, this is advanced stuff.
Anyhow-The Zone System (ZS) was developed by Ansel Adams, but was made usable by Minor White and Dick Zakia. ZS attempts to co-ordinate all steps in creation of the image from viewing and metering (Pre-visualsation and placement), contrast control in the development of the negative, and the end goal of producing a negative optimal for printing the image as originaly envisioned by the photographer during previsualization.
This is achived through a series of practical and methodical tests preformed on the paper (print making system including the enlarger, paper, and developer) to determine the optimum film contrast. This is the range from shadows to highlight in the negative. This information is then used to make a series of tests to determine working film speed and development time for a given scene brightness range. Let me insert here that the greyscale spectrum from black to white has been broken into ten "zones", each a stop apart. A "Normal" scene will have ten stops difference between it's darkest and lightest components not including specular highlights. However detail will be held between zones III and VII beyond that detail is lost. This Normal scene is denoted as N and has five stops between shadow and highlight detail. A scene which has 4 stops between these detail points is refered to as an N+1 scene since it will need to be streached by on stop to produce a negative with the same density range as an N scene. Likewise a scene that has 6 stops between these key points is refered to as an N-1. Testing is usualy done from N-2 to N+2.
With this information in hand you can meter a scene and determine how to expose for shadows (place), where the highlights will be (fall), and what development factor to apply to the negative. With this new understanding of tones the photographer is also better able to see the scene before him and determine how they wish the tones to be rendered (pre-visualasation).
With all this said I should state that I developed a system of my own based on a special method of incident metering (measuring the light falling on a scene), an understanding of maximum and minimum posible reflected values, and local vs overall contrast. The principles of testing and negative control remain in place though. I discovered this is similar to the method pu forth by Phil Davis in his book "Beyond the Zone System".
I know this is off topic, but we have a number of people interested in photography on the board. I have a hard copy of an old post I made to an advanced usenet group and if there's any interest I'd be willing to dig try and scan it to a text file with an OCR program and post it here. Sing out if you want me to post it.
02-25-2005, 02:52 AM
What a well-written summary of the zone system! Ansel Adams made the zone system pretty much a household word among dedicated b&w photogs. to BillH -you can get further info at the library of any college that has a photography program, and probably at the public library too. The only thing I would like to add is in regards to the film and paper you use. I seem to remember reading somewhere that most modern b&w films can capture from 15 to 22 stops of detail, much more than most papers can capture. This latitude in films make them much more forgiving to slight overexposure. Modern b&w films have a two layer emulsion (a fast and a slow layer) to give them the needed resolution. However, these two layers do reduce the resolution and accutance of the film a little bit. Some of the slower, high resolution films give greater accutance and resolution at the expense of latitude. I've been messing around with Lith film in my 4X5, developed in a low contrast developer. I shoot the film at iso 5 and develop it in Rodinol at 1:150 for about 7 minutes 68F. You can develop it in trays with the safelight on and watch it develop since it's orthocromatic film (not red-spectrum sensitive). cool. It yields thin latitude (your exposure has to be dead on), but the sharpness and lack of grain is just unbelievable. I use incident light metering too with some reflective readings on the difficult to meter stuff. I have an old gossen lunasix pro with a spot attachment. The detail in 16X20 prints from the 4X5 is just stunning. My brother shoots a nikon d100 6mp digital slr. Nice camera. People look at his 11X14 prints and say "that's really nice". They look at the 16X20's from the 4X5 and go "oooohhhh". Drives my brother nuts....
02-25-2005, 01:06 PM
I just have the center weighted built in lightmeter on my camera. Dave, if its no trouble sure, post it, I will print it out and read it. Otherwise I will just as happily look up some books on it. Like to hear your method of it. Lately I have been paying much more attention to composistion, and cropping out objects that distract the eye from the main target.
I've been using kodak Tri X 400 film, and Ilford resin coated #4 pearl paper.
I took another picture of a train, it impressed me so much that I already put it in a frame. I think my first roll of film got some light on it, because all my images are much more contrasty in the 2nd roll. THe darn darkroom at school has gaps in the weather stripping, if your back is not against it, light leaks in. 2nd roll I did at home in a change bag.
02-26-2005, 01:28 AM
Thanks, George Dewolfe was my mentor and Minor White and Dick Zakia were his. http://www.shutterbug.com/features/0804sb_george/ George was my main instructor in college, I was his lab assistant.
If you like VTE film (Very Thin Emulsion) I recommend TechPan if it's available. It is panchromatic. Photographer's Formulary used to make a special developer for it. I think it may have been a phenodon-based developer. It was also extremely fine grained: 16x20 from 35 with no visible grain. Focusing the negative was a bitch! Had an effective ISO of around 32. I think others were using Rodinal with it as well.
Tri-X is nice because it has no effective shoulder in the highlights so it doesn't get as chalky. It's probably my third favorite film (developed in Rodinal), My second favorite would be Ilford's Delta 400 also in Rodinal. It uses a crystalline technology similar to T-max but has a characteristic curve similar to tri-x. My First favorite would be Delta 400 and my own phenodon based developer. I stay away from D-76 and other Hydroquinone-Metol based developers for film. Especially D-76 which has to much Sodium Sulfite which melts the metallic silver edges to reduce the apparent grain. This also reduces acutance. It's also heavy on the KBr as a restrainer, which can hold back shadow detail and reduce film speed. It also impairs adjacency effects, which can improve sharpness (SUBJECTIVE). Rodinal is grainy but it’s SHARP and FAST. Getting close to the rated speed of the film is not unusual.
On the subject of film latitude, Almost all modern films have a characteristic curve that places the shoulder well above a density of 1.25 so yes it's possible for the film to record that much range, but it's still useless! Where this breaks down is in the enlarging stage. As light passes through the silver grain it undergoes diffraction and scatters. This increases geometrically with increased density until more light is scattered than passed through unchanged. Such diffraction is what produces chalky highlights. Also, in films using Ag-Br salts in the emulsion, bromide is released in development. Bromide is a restrainer and will retard development in extremely dense areas. It is possible to reverse the curve in such cases. Using a diffuse light source in the enlarger will make the scattering of light evenly throughout the negative, and will allow for a negative with another stop (0.3) of range so highlights can be as dense as 1.55, but at the cost of some sharpness. I don't care for cold light prints myself. Zeiss made use of this phenomenon and held a patent for a variable contrast enlarger. Light from a polarized source was used. The light passing through the low-density areas of the negative would remain polarized, but light that became diffracted in the dense areas also became unpolarized. Using cross polarization from a second filter would effectively add density to the shadows and reduce contrast. Aligning the second filter with the first would remove the light, which had become unpolarized in the highlights and increase the effective contrast.
Since this scattering is caused by the physical presence of silver there are some interesting options. VTE films are one option. The thin emulsion reduces the scattering. C-41 (or whatever's current) based film has some potential since the silver is removed during development leaving only dye in its place. The dye does not cause refraction as the silver crystals do. I remember a film like this that had a very unusual curve. It was an like an exponential curve, so contrast could be controled through exposure. Increasing exposure moved the scene up the curve and it thus became more contrasty, and denser, but since there was no silver remaining there was no difraction and thus the neg was still printable. Pyrogallo and other staining developers add density to highlights through staining. These can be tempormental and toxic. I'd like to play with them but never got the chance.
There are some other interesting methods I know of. Compensating developers are the most common, but I think they're counter productive and basicly have the same effect through chemichal manipulation. You want to head in the opposite direction. Laitent Image Manipulation is interesting and has some promise. Basicly it involves the use of highly diluted bleach formulations (Potasium Cyanide) to partialy bleach the latent image prior to development. Since the bleach acts disproportionaltly on low density areas it can be used to control contrast as well.
The method that I was playing around with was a very sophisticated contrast masking during printing. Using kodalith and positive masking films in first in high contrast forms and then in extreamly weak developers to make very faint images I was able to seperate the manipulation of local and overall contrast control.
Ok, that's enough for tonight.