120 vs. 220 Rollfilm Holdersgreenspun.com : LUSENET : Large format photography : One Thread
I need to purchase a Horseman rollfilm holder for a 6x9 camera. They come in either 120 or 220 versions. My questions:
Has anyone tested the film flatness for 120 film versus 220 film for Horseman rollfilm holders?
Has anyone performed this test with the Mamiya 7 or Linhof Technorama 612PC II (cameras which can use both 120 and 220 film) to see if indeed 220 film was superior in terms of film flatness?
Does anyone have a preference in this matter (from personal experience using both 120 and 220 rollfilm holders). Pros and cons of going one way or the other.
-- E Rothman (email@example.com), March 13, 2002
I use both film sizes routinely and find no practical difference between the two. I have owned holders that were damaged in such a way that they caused either lack of sharpness, scratching, or some other gremlin.
In the distant past, people have tried to sell me on the superiority of one of the other, but I never saw convincing evidence.
It's far more important to make sure your holders are clean, and that the camera they mate with isn't warped.
On your last question; my Fuji cameras show no difference at all between 120 and 220 if everything is set correctly, but have the pressure plate on the wrong setting and you'll wind up with a mess!
-- Brian Yarvin (firstname.lastname@example.org), March 13, 2002.
Here's a link to more info than you will probably want:
-- Jim Bancroft (email@example.com), March 13, 2002.
Theoretically, Film Flatness is better for 220 Film, because of simple mathematics. Since the paper is on the outside of a 120 roll, it has a slightly larger circumference on the roll. As long as the film lies tight on the pressure plate (e.g. just after advancing a frame), this may not be a real problem. But this tense loosens after a certain time and may cause flatness disturbances. Another issue is whether the film is bent before exposure (bending after exposure does not matter). This lies within the construction of the holder. If the film is bent before exposure, it may get deformations after a certain time that disturbs flatness as the frame is advanced. Zeiss has done some investigations on this issue. You can find an article in Zeiss Camera Lens News No 10, available on their website.
Rollfim Flatness is usually less an issue in LF, because tolerances are anyway higher than in MF. Sheet Film, e.g., can move as much as 0.3mm in the holder. The tolerances between Ground Glass, Film Holder Stop and Film Plane in the holder is usually higher than Film Flatness in a Roll Film Holder alone. This is different with a Mamiya 7, because tolerances are tighter in MF, the film plane is defined more exactly and the lenses usually deliver more resolution (e.g. f8 is more common to MF than to LF)
-- Thilo Schmid (firstname.lastname@example.org), March 13, 2002.
In some film holders where the film is submitted to tight curves, the backing paper of 120 can induce a film unflatness especially if the film has been sitting still for a while in the back. Therefore it is recommended that you take two shots at the start of a new work cession, one of the two being perhaps affected. The wider the format, the worse this can be. In practice, I have not found it to be a problem with the Sinar back and use indifferently 120 or 220. If the bend induced by the filmholder is tight, this can become a problem. I had a Cambo 6x12 and needed the 220 films for the best results. I don't know how the Horseman behaves, but it's likely a good back. The second thing to consider is the availability of 220 films, 120 being more readily available, and also that some processing labs won't process it correctly. I have had many 220 damaged by my lab. Also, a 220 roll can be too much for some situations, especially if you have only one back and need to switch film. Good luck!
-- Paul Schilliger (email@example.com), March 13, 2002.
"As a rule of thumb: For best sharpness in medium format, prefer 220 type roll film and run it through the camera rather quickly." from a report on film flatness in the medium format section of the Zeiss web site: http://www.zeiss.de/C12567A8003B58B9?Open
-- Hank Graber (firstname.lastname@example.org), March 13, 2002.
More specifically to Hank's point: Zeiss did a research study on the issue. Summer, 2000. Liank:
Here is what they said:
"Is Roll Film 220 better than 120 in terms of film flatness? Zeiss has recently developed a new measuring system to evaluate film flatness in medium format photography. The new system is based on an computerized microscope that can automatically scan and focus on multiple points of a film frame in a medium format camera magazine. The obtained focusing data are recorded by a computer and evaluated by a propriatory Zeiss software. The result is a mapping of the film topography with an accuracy of one millionth of a meter (1 micron), according to the developer of this system. The purpose of this new device is to find out how well film magazine mechanics are designed in today's medium format camera systems, how precise they position the film and how well they hold it flat. From these findings Zeiss can draw conclusions about the field flatness required for medium format lenses and Zeiss can also trace causes for lack of sharpness in customer's photos. This is particularly interesting since more than 99% of all customer complaints about lacking sharpness in their photos can be attributed to misalignments of critical components in camera, viewfinder, or magazine, focus errors, camera shake and vibrations, film curvature, and other reasons. So far, Zeiss has found that film curvature can have a major influence as a source of unsharpness. This has also been known by Zeiss' camera making partners Alpa, Hasselblad, Kyocera (Contax) and Rollei. Since Zeiss' evaluation program is not completed yet, we would like not to draw too many conclusions prematurely. But two things can be stated already as hints to enable sharper photos with medium format cameras at wide open apertures, since exactly those are invited by the high level of aberration correction in Zeiss lenses: 1. 220 type rollfilm usually offers better flatness than 120 type by a factor of almost 2. This is an advantage with fast, motorized cameras like the Contax 645 AF, Hasselblad 555 ELD (and previous motorized Hasselblad cameras) and Rolleiflex 6000 series cameras. 2. Film flatness problems are mainly caused by the combined influence of two factors: the rollers in the camera or magazine that bend the film, and the time a certain part of the film is bent by such a roller. Camera manufacturers usually space the rollers in a way that bent portions of the film will never be positioned near the center of the image. Therefore only marginal regions of the image should be affected by sharpness problems due to film flatness errors. Since the photographer cannot alter the geometry and mechanics of his camera, he can only influence the other factor: time. A film run through the camera without much time between exposures should result in good flatness and hence sharpness. Five minutes between exposures may be some sort of limit, depending on brand and type of film. 15 minutes are likely to show an influence of bending around rollers. Two hours definitively will. As a rule of thumb: For best sharpness in medium format, prefer 220 type roll film and run it through the camera rather quickly." Zeiss: Camera Lens News No. 10, Summer 2000
-- Julio Fernandez (email@example.com), March 14, 2002.
Another consideration may be film availability. Not all emulsions are available in both 120 and 220. I chose 120 holders to have a greater choice of films.
-- Chris Ellinger (firstname.lastname@example.org), March 14, 2002.