b._weiner

The 86 degree horizontal field of view that Michael Cheetham refers

to would apply to a 30mm RECTILINEAR lens on 6x6 film (a 56mm square

negative). That formula doesn't apply to a fisheye. The point of a

fisheye is that it offers more angular coverage (and a unique

perspective) by giving up rectilinear perspective - straight lines appear curved.

Umm, not to be a curmudgeon, but you've got the lenses - why don't

you take a few rolls as a test and tell us how the lenses are? Also, any generic comments might not apply to the individual lens that you happen to have. That said, they all have a pretty good reputation.

Use whatever aperture you need to get the depth of field you need (note that the DOF markings on the lenses are about 1 stop optimistic,

or worse if you want to make really big enlargements).

<p>

If you want to use the back movements (or the extension tube set which is available as an accessory), you will need a ground glass back to focus, as the rangefinder is not acccurate once you start extending the back. It attaches and detaches like the roll film backs. You can

use 2x3 cut film in holders, though 2x3 sheet film only comes in a few

emulsions. I prefer to use the GG back with rollflm backs - you attach the GG, focus, then detach it and attach the rollfilm back.

Use a loupe to focus on the groundglass.

Generally the lens manufacturer supplies a plate which is calibrated

to show the right f-stops for the lens - since any number of

different lenses can come in a copal 1 shutter. Your lens may

have been remounted in the shutter. You can probably work out

approximate f-stops by measuring the iris opening as seen from

the front of the lens - full open is f/5.5, when the iris opening

is half of full, that's f/11, and so on.

Ooops!!! Another question from Chris prompted me to realize

that I made a dumb mistake. The 0.197" depth is for 4x5

holders, and doesn't apply to 8x10 holders. I don't know the

ISO standard for those, but Chris reported a depth of

0.255" - 0.265", and when I quickly re-measured one, I got

about 6.7 +/- 0.3 mm (0.26" +/- 0.01").

How good a machinist are you?

<p>

The lenses could be removed from the focusing helicoids and mounted

like any other lens-in-shutter, on a plain board with the right size hole. But you probably don't want to do that. You would also lose

the PC socket as it's attached to the helicoid.

<p>

You could make a flange which accepted the bayonet mount - this is where the machining comes in - or salvage the flange from a trashed

Mamiya body or an extension tube set, and mount that flange to a 23 Graphic lens board somehow (more machining). Two potential problems: 1) with the helicoids, most of the lenses are heavy (except the 65mm), and all that weight will be cantilevered out in front of the front standard, which might tilt. 2) The bayonet is about 3-3/8 inches across. I don't know if that will even fit on a 2x3 Graphic lens board; it would only just fit on the 4" square lens boards common on smaller 4x5 cameras.

The standard film holder depth is 0.197 inches and film is

assumed to be 0.007 inches thick, so the surface of the film

is 0.190 inches (4.83mm) back from the face of the film

holder. This is very very close to 3/16 inch (0.1875 inches)

so using a 3/16" shim might be the easiest way to get the

glass at the right depth.

<p>

If you are building the back from scratch, get hold of a film

holder first to get the dimensions right, especially to get the

slot for the light-trap ridge correct. New 8x10 film holders

are pretty expensive. Even used modern (plastic) ones are fairly

pricey. Older wood ones can be cheaper but make extra sure

they are in good shape, light tight, and not warped. Condition

is more important than brand name.

The Mamiya fits the criteria you have, as long as you can live

with its idiosyncracies: 1) it's a rangefinder not an SLR,

2) it's rather large, though so are most 6x9 cameras, 3) there

are no interlocks between film advance and shutter, and no interlocks

between lens, back, and darkslide, so you have to remember to insert/

remove the slide when changing lenses or backs. On the other

hand, this means there are relatively few complex linkages, so they

are pretty durable.

<p>

There are several different kinds of bodies: Press, Super 23, and

Universal. The Press is older, it comes in a version with a rear

bellows and without, and has a sort of squinty viewfinder. The

Super 23 has rear bellows, a nicer VF with bright framelines, and is

a bit heavier. The Universal is like a Super 23 but does not have

the bellows, however it is the only one which can take a Polaroid back. (The rear bellows extends on four posts and can be used for tilt/swing with a 90 or 100mm lens which retracts into the barrel, or for macro with any lens, but you'll need a groundglass back to use it, as the RF will not be accurate.) Press bodies are quite cheap, Super 23s are a bit more, Universals seem to be more expensive. Oh, all

bodies take a handgrip with cable release on the left hand side, make

sure you get that with the body.

<p>

The Universal takes either a Polaroid back or an "M-frame" which takes Mamiya Press roll backs, or a "G-frame" which takes 2x3 Graflok roll film backs. The Press and Super 23 generally come with the M-style back, so they only take the Mamiya roll backs. However, some were

made with G-style backs and only take the Graflok - you probably

don't want that if you don't like the RH-8. The Mamiya roll backs

are "S" shaped and don't put a strong reverse curl in the film,

unlike the Graflok backs; they have no problems with film flatness. The S-shape also provides convenient grips which make the camera easy to hold despite its size. There are a bunch of different

models of backs but they all seem to hold the film flat.

Lever wind backs are nicer than the knob wind ones.

<p>

Lenses for the Mamiya were 50mm/6.3, 65/6.3, 75/6.3, 90/3.5, 100/3.5, 100/2.8, 150/5.6, 250/5, and 250/8. All but the 250/8 couple to the RF. If you get a wide angle (50,65,75) you also need an accessory

viewfinder. The lenses come in "black" and "chrome" styles which

refers to the shutters. Mamiya still repairs the black shutters;

they don't service the chrome shutters, but the shutters are relatively sturdy, and I'm sure there are independent repairmen who can work on them. Anyway, the chrome lenses can sometimes be found

so cheaply that it almost doesn't matter.

<p>

There are about a bazillion different accessories ranging from

common and useful (extension tubes, groundglass back) to obscure and esoteric.

<p>

If you search the Dejanews archive (www.dejanews.com) in

rec.photo.equipment.medium.format, you should find some posts about

the Mamiya.