DannyTreacy
Member
Hi all,
Does anyone have any real world exposure compensations for using the Mamiya extension ring set for the press cameras?
Lots of threads have been posted over various forums with no definitive answer.
So has anyone got a simple record of the necessary exposure compensation?
(e.g. No.1 ring = 0.50 stop exposure compensation, No.2 ring = 1.00 stop exposure compensation).
I'm not interested in any of the hard math formulas, that inevitably ends in forum members disagreeing over things, just real world users, thanks!
Danny.
Does anyone have any real world exposure compensations for using the Mamiya extension ring set for the press cameras?
Lots of threads have been posted over various forums with no definitive answer.
So has anyone got a simple record of the necessary exposure compensation?
(e.g. No.1 ring = 0.50 stop exposure compensation, No.2 ring = 1.00 stop exposure compensation).
I'm not interested in any of the hard math formulas, that inevitably ends in forum members disagreeing over things, just real world users, thanks!
Danny.
oftheherd
Veteran
Dwig
Well-known
Sorry, but the physics that rule the universe we live in prevent there being a answer quite that simple. That's why you haven't found one.
The effect of an extension tube on exposure, focusing distance, and magnification varies with the focal length of the lens. Any list of exposure compensation would have to be in the form of a table/spreadsheet with columns for each FL lens made for the camera and rows for each total extension of the various combinations of tubes. Such a chart could be made accurately for use with the lenses set to their infinity setting and would be slightly inaccurate when the lenses were set to other focusing distances, though usually only a 1/2 stop at the most.
oftheherd
Veteran
The below may help as well. Someone correct me if I am wrong, but I think using bellows factor gets you where you need to be. I also think there was something in the Mamiya instruction book that came with the Super Press 23. If I recall, I will try and find mine and check that.
http://people.umass.edu/~rbhome/bellows15.pdf
http://www.largeformatphotography.info/bellows-factor.html
http://people.umass.edu/~rbhome/bellows15.pdf
http://www.largeformatphotography.info/bellows-factor.html
oftheherd
Veteran
This may be useful unless the extension tubes are not equated to bellow factor.
http://www.ndavidking.com/Tech Articles/Bellow Factor Illustration.pdf
http://www.macrobellows.com/technique.php
http://www.ndavidking.com/Tech Articles/Bellow Factor Illustration.pdf
http://www.macrobellows.com/technique.php
Dwig
Well-known
+1, with one additional consideration.
Most view camera "bellows factor" discussions talk about measuring from the lens to the film. When dealing with lenses with their own focusing mechanism and intended for normal use mounted directly on a body, the lens' own extension from the film (equals the focal length when focused to infinity) needs to be added to the extension tube's length to get the total extension from lens to film to "translate" to View-Camera-eze.
oftheherd
Veteran
I think I saw that covered in one of the links, but thanks for ensuring that was specifically brought out. And for the OP, it would be to the film plane whether the film holder was next to the body, or pulled out as on a Super Press 23. The measurements and calculations allow you to use any single tube or any combination.
It isn't necessary, but highly recommended to get a cut film holder, such as listed in this ebay listing: http://www.ebay.com/itm/MAMIYA-Focu...719?pt=LH_DefaultDomain_0&hash=item2a4b4f7bff rather than any of the 3 others that I know of. They are usually cheaper, and if you want to get one, you should check all other listing, including Craig's list or other local listing.
The ground glass makes for much easier focusing.
oftheherd
Veteran
If you don't have it, you might want to look at this if you have the Super Press 23: http://www.cameramanuals.org/mamiya_pdf/mamiya_press_super_23.pdf
DannyTreacy
Member
Hi,
I contacted a guy on ebay who was selling a boxed ring set with instructions, he took a photo of them, here they are for the 100mm 3.5 lens:
Mamiya Press Extension Tubes exposure Compensation Guide.
Using 100mm Lens.
All calculations are for lens focused at closest distance, not infinity.
Ring Combination Magnification Exposure factor
1 + 2 0.11 – 0.34 1.5 (0.75 stops)
1 + 3 + 2 0.31 – 0.54 2.0 (1 stop)
1 + 4 + 2 0.51 – 0.74 2.6 (1.25 stops)
1 + 3 + 4 + 2 0.71 – 0.94 3.3 (1.75 stops)
1 + 3 + 4 + 5 + 2 0.91 – 1.14 4.0 (2 stops)
I contacted a guy on ebay who was selling a boxed ring set with instructions, he took a photo of them, here they are for the 100mm 3.5 lens:
Mamiya Press Extension Tubes exposure Compensation Guide.
Using 100mm Lens.
All calculations are for lens focused at closest distance, not infinity.
Ring Combination Magnification Exposure factor
1 + 2 0.11 – 0.34 1.5 (0.75 stops)
1 + 3 + 2 0.31 – 0.54 2.0 (1 stop)
1 + 4 + 2 0.51 – 0.74 2.6 (1.25 stops)
1 + 3 + 4 + 2 0.71 – 0.94 3.3 (1.75 stops)
1 + 3 + 4 + 5 + 2 0.91 – 1.14 4.0 (2 stops)