required bellows length for 610 apo-nikkor f/9 on 8x10

[djkloss]

It's a quickie question as my photography books are all in storage until I get moved. I need to know how much bellow I would need if I had one of these. I don't know if it has a shutter or if it matters. I have the Kodak 2D 8x10 with no extra extension bellows.

thanks!

Dorothy

 

[Maris]

I use a 610mm f9 Apo-Nikkor on my triple extension Tachihara 8x10 and it needs pretty exactly 600mm of bellows to get infinity focus.

 

[polyglot]

How much magnification do you want? Assuming it's a simple lens (unity pupil factor), then

bellows = (M+1) * F

where M = magnification. So about 610mm to do infinity (M=0) and 1220mm to do a headshot (M=1). Maybe 700mm for a full-length portrait (M=0.125).

 

[djkloss]

Well, I only have 500mm from lens board to film plane so I guess that lens is too long for the camera I have. I think I'd prefer a petzval anyway. Any suggestions on FL for an 8x10 petzval? Same deal? no more than 250mm if I want a head shot? (1:2) ?

 

[Dan Fromm]

Dorothy, the 610/9 Apo-Nikkor's cataloged weight is 1,450 g. Not that heavy. Its mounting threads are M110x1.

With a little effort you should be able to cobble up a thick board that will hold the flange ~ 4" in front of your 2D's front standard. I use 4" PVC drain pipe, lined with flocked paper, for an extension tube but my camera is modular so I can put the extension tube between a pair of standards.

What did you intend to use for a shutter with a 610? Believe it or not I hang mine (in a pricey adapter from SKGrimes) in front of a Copal #1. I shoot much smaller than 8x10 -- my largest is 6x12 -- with no vignetting issues. Believe it or not again, if I've done the calculations correctly my lens hung on a #1 as I use it should cover 8x10 at infinity with room to spare. If you take this approach you'll need to add ~ 2" of extension -- shutter and adapter add > 2" -- to get to 1:8 as recommended by Polyglot. I'd use wood to make a thick board.

Oh yes. The 610's exit pupil is 67.8 mm in diameter at f/9. A #1's aperture is 30 mm in diameter. When the lens is wide open, the GG/film plane gets whatever illumination the lens gives at f/9. The lens' diaphragm has no effect on illumination at the film plane until the relative aperture is slightly larger than f/16. This is where the lens' diaphragm begins to be visible through the back of the shutter. At this point the exit pupil's diameter should be a little larger than 38 mm. This seems impossible, but I've seen it, don't find having to shoot at f/16 or smaller much of a handicap.

Good luck, have fun,

Dan

 

[polyglot]

Oh yes. The 610's exit pupil is 67.8 mm in diameter at f/9. A #1's aperture is 30 mm in diameter. When the lens is wide open, the GG/film plane gets whatever illumination the lens gives at f/9. The lens' diaphragm has no effect on illumination at the film plane until the relative aperture is slightly larger than f/16. This is where the lens' diaphragm begins to be visible through the back of the shutter. At this point the exit pupil's diameter should be a little larger than 38 mm. This seems impossible, but I've seen it, don't find having to shoot at f/16 or smaller much of a handicap.

I think you have this a bit mixed up. If the shutter is occluding the view through the lens (as viewed from the film plane), it is acting as a secondary aperture and therefore you do not get f/9 worth of light (in terms of exposure or DOF). If the lens' own aperture starts to become visible at f/16, then your shutter is limiting you to f/16. You could shoot "wide open", but "wide open" is now f/16 because of the shutter. However I would have expected more like f/20 (610mm / 30mm).

Anyway. A 500mm bellows on an 8x10 camera seems really short to me. I have about 300mm on my 4x5 field camera (Toyo) and that's rather lacking. If I were you (Dorothy), I would look into means of extending the bellows, because they're going to be very limiting with any lens you might want to use. For example with a 300mm (short normal) lens, you can get only 0.66x magnification, which means the smallest subject you could photograph without using a wideangle lens is about 15 inches long. You would need to use a 240-250mm lens to reach 1:1 and make a headshot, and you'd be right up in their nostril to do it.

 

[Dr Croubie]

I've got a 465mm Apo-Ronar and 600mm Apo-Tessar hanging in front of a #1 Press by a mounting flange, by happy coincidence they both have the same 95mm (or whatever) thread so it's easy to change between the two.
For bellows extension, now that Polyglot's sold me a 'real' Toyo 45G, I just got another standard (45GII even), another rail, and another bellows to increase extension, there's no real limit to how long I can make it.
On my new Cambo SC 8x10 the bellows goes out to about 600mm, if I invest in more cambo standards/bellows/rails I can similarly extend that.
Unfortunately I don't know enough (anything) about a Kodak 2D to know if it's similarly extendable. But as stated, 610mm lens needs 610mm of bellows (or near enough) just to get to infinity, longer for more macro, unless you buy a (real definition of a) Telephoto lens.

Speaking of the reduced coverage from front-mounting, I'm intrigued. I always thought that because the light-rays have stopped bending once they're out of the lens (for a symmetrical-enough lens with pupil inside the lens), that the effect of the shutter (if any), is just to vignette the IC, not reduce the aperture (as per Grimes, no mention of aperture near the sketch at the bottom). Then again, I could be wrong (which, lets face it, is highly likely).
Not that I'll be shooting at 600mm f/9 on 8x10, that's DOF like 85mm f/1.2 on 35mm, some people like that, but my subjects never sit still enough and 8x10 film is expensive to re-shoot.

 

[djkloss]

Thank you all for all the great information. A friend of mine was asking if I were interested in buying/trading so I was trying to read up on it before hand. I may just ask if I can test it out. This is a lot of excellent information given and I thank you all for that! Since I can't be at photostock this year I will print out this thread and read it and figure out what i'm doing.

Thanks again! Dorothy

 

[polyglot]

Speaking of the reduced coverage from front-mounting, I'm intrigued. I always thought that because the light-rays have stopped bending once they're out of the lens (for a symmetrical-enough lens with pupil inside the lens), that the effect of the shutter (if any), is just to vignette the IC, not reduce the aperture (as per Grimes, no mention of aperture near the sketch at the bottom). Then again, I could be wrong (which, lets face it, is highly likely).

It depends on the exact geometry, mostly how far the shutter is from the lens' centre. Obviously if the shutter is at the film plane then it is as you say - you will get no attenuation but only a tiny image circle. However if the shutter is nearer the lens, it acts more like an aperture. At some small distance from the lens, you start to get a mixture of both effects, i.e. it will darken the image but moreso near the edges. You can figure out the effect by sticking your eye in the film plane and looking at the back of the lens:
- no occlusion = no reduction of light
- shutter hides the outer edges of the lens (hides your view of the lens' proper aperture) = behaving like a smaller aperture
- shutter asymmetrically hides the lens (occurs for points off-centre) = behaving like a small, uneven aperture; results in vignetting and cats-eye bokeh

The fraction of the area of the aperture that is hidden by the shutter (when looking from one specific point on the film) will tell you exactly how much attenuation you get from the shutter, at that point on the film. Since the shutter isn't inside the lens, that fraction will not be uniform across the film plane (looking from different angles); as you move your eye towards the corners, the shutter will occlude more and more of the lens and therefore the corners of your image will darken progressively (vignetting) and the bokeh will take on a lenticular/cats-eye form, tangential. At some extreme angle, the shutter completely occludes your view of the lens (the cats-eye has closed entirely), and this defines the new, reduced image circle from the lens+shutter combination.

If you repeat the above peering experiment wide-open and at a smaller aperture (like f/45 or something) then you will directly observe how stopping down reduces vignetting; there's less aperture to be occluded, so you must go to more-extreme angles to have any effect from the offset shutter. And when the vignetting kicks in, it will do so much more-rapidly.

 

[Dan Fromm]

I think you have this a bit mixed up. If the shutter is occluding the view through the lens (as viewed from the film plane), it is acting as a secondary aperture and therefore you do not get f/9 worth of light (in terms of exposure or DOF). If the lens' own aperture starts to become visible at f/16, then your shutter is limiting you to f/16.

Polyglot, what you said is entirely reasonable and is, in fact, what I expected to find since the obstruction (#1 shutter) is close to the back of the lens. But and however, I've shot E6 with the 610 wide open and mounted as described. The shutter used to take the exposure was a focal plane shutter whose speeds had been measured. I got perfectly exposed transparencies when I took my meter's advice and trusted the FPS. I'd have expected slightly more than one stop underexposure, didn't get that.

 

[DREW WILEY]

You'd want around thirty inches of bellows for typical use; unless you expect to use it strictly at infinity. And there would be no sense of using
a lens this long for very closeup work on an 8x10.