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12-25-2009, 05:49 AM   #16
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QuoteOriginally posted by ytterbium Quote
nono... i dont mean to use it at film plane. Otherwise it migh just be more economical to get a real shutter.

Im thinking of something like this:
canon 20 d shutter assembly camera spare parts exporters importers delhi
Placed just behind the lens, and other externally servicable parts. Something like in the image attached.

But what makes me wonder is how a slit placed near aperturewould affect image rendering. I'm thinking it would produce an effect like this:
Have Fun with Aperture Shapes! on Lomography
Only with even smaller slits some diffraction effects might kick in as well.
If so only speeds up to flash sync (fully open) could be used.

This is cheap:
PENTACON SLR PRAKTICA CAMERA SPARE PART SHUTTER NEW NR - eBay (item 230405740066 end time Dec-29-09 09:13:11 PST)
But pretty bulky. Probably i could find a film camera with fully electronic shutter (means slim) and something else broken, cheaper.

And MERRY CHRISTMAS!
Are the effects of the Lomosite what you want to achieve? If yes, be aware, they place shapes IN FRONT of the lens to modulate the shape of light sources. Behind the lens, you'll only get vignetting.

If you are after something else, it would be easier to make a suggestion, if you'ld explain, what you want to achieve.

Ben

12-25-2009, 06:34 AM   #17
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I plan on using bare conventional focal plane shutter from 35mm slr in medium format camera.
Since such shutter would be too small for use at focal plane, i plan to place it just behind the lens.

The question is, what effects can i expect and how to avoid them.

Btw, is my English that bad? I've been trying to explain this in 3 replies already. .
12-25-2009, 01:48 PM   #18
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QuoteOriginally posted by ytterbium Quote
I plan on using bare conventional focal plane shutter from 35mm slr in medium format camera.
Since such shutter would be too small for use at focal plane, i plan to place it just behind the lens.

The question is, what effects can i expect and how to avoid them.

Btw, is my English that bad? I've been trying to explain this in 3 replies already. .
It's more probable that I am challenged, English-wise… But I still don't get, what "effect" you would expect from a focal plane shutter placed behind a lens, apart from severe vignetting, as the shutter's opening will not be large enough? There are no effects from shutter travel, which would be different from those you may expect from using your ordinary DSLR with its ordinary shutter. That means, you could have some nice stretched images, when photographing very fast objects moving parallel to the shutter's firing direction. You find nice examples in 1960'/60's photographic books and magazines, when this was novel. Modern shutters usually travel vertically and much faster, than the old horizontal shutters (Pentax MX, LX etc. for example), so even this effect is hard to achieve, if at all.

Ben
12-25-2009, 02:04 PM   #19
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Ben, he's expecting the shutter's opening to be big enough if it's placed closer to the lens instead of just next to the film. I can see it might help, but I don't know if it'd be enough.

Interesting project!

12-25-2009, 02:12 PM   #20
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QuoteOriginally posted by brkl Quote
Ben, he's expecting the shutter's opening to be big enough if it's placed closer to the lens instead of just next to the film. I can see it might help, but I don't know if it'd be enough.

Interesting project!
I think I got that. But a 35mm shutter is way too small, even placed directly behind the lens and will show heavy vignetting. And there will be no interesting "effects" visible, apart from said vignetting. That's the point I try to make. To be helpful, I need to understand, what "effect" ytterbium expects.

Ben
12-25-2009, 06:01 PM   #21
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Not effects as in special effects, just effects of placing the shutter there, and from what I gather he doesn't want any.

The in-lens shutters I've seen have been between lens elements next to the aperture leaves, so the shutter has to open up to just as big as the largest aperture. This doesn't seem viable.
12-25-2009, 07:23 PM   #22
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Well then i guess i should start by getting a real lens. One that is actually made for medium an bigger formats. Otherwise my current impression is formed by the small plastic excuse for a lens in my 6x9 box camera with it's 1cm diameter shutter .

So an 80mm f/3.5 lens will have 22.857mm diameter opening.... true.. damn close to 35mm frame size.
12-26-2009, 11:13 AM   #23
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QuoteOriginally posted by ytterbium Quote
Well then i guess i should start by getting a real lens. One that is actually made for medium an bigger formats. Otherwise my current impression is formed by the small plastic excuse for a lens in my 6x9 box camera with it's 1cm diameter shutter .

So an 80mm f/3.5 lens will have 22.857mm diameter opening.... true.. damn close to 35mm frame size.
Ah, now I think I understand our little communication problem. No, the 80/3.5 won't have a 22.857mm diameter at the iris position. What you see and measure from the outside (the front to be precise) is the so called "entrance pupil". This would appaer as having that said diameter. BUT in reality it could be more or less, because the entrance pupil is only a projection through the lenses. If you look from the mount into the lens, you'll see the exit pupil. This has the same diameter as the entrance pupil, if you have symetrical lenses (for example Gauss types). But if you have a highly asymetrical lens, like most tele lenses or wide angles, the ewxit pupil may have a very different diameter from the entrance pupil or the real mechanical diameter of the aperture (and leaf shutter).

Ben

12-26-2009, 12:18 PM   #24
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Interesting point. If i understand it correctly, this means that with some lenses i could even achieve this, but with others not - even if the theoretical aperture size is smaller than 35mm frame.

What type of lenses would you recommend for an experimental medium-to large format camera. Say, i'd like to have a wide FOV (equivalent to 28 or less mm for 35mm film) and ability to cover at least 6x9cm frame. Quality is more important than maximum aperture.
12-26-2009, 01:45 PM   #25
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QuoteOriginally posted by ytterbium Quote
Interesting point. If i understand it correctly, this means that with some lenses i could even achieve this, but with others not - even if the theoretical aperture size is smaller than 35mm frame.

What type of lenses would you recommend for an experimental medium-to large format camera. Say, i'd like to have a wide FOV (equivalent to 28 or less mm for 35mm film) and ability to cover at least 6x9cm frame. Quality is more important than maximum aperture.
Hey, btw, if you're still interested, I think I was incorrect about where I saw these lens-shutters I mentioned: the catch is, they're for a Camerz system (There's the name I was forgetting) , and the shutters are electronic. You could Ebay search on that.

I think I heard you mention some facility with electronics, though.
12-26-2009, 01:50 PM   #26
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QuoteOriginally posted by ytterbium Quote
Interesting point. If i understand it correctly, this means that with some lenses i could even achieve this, but with others not - even if the theoretical aperture size is smaller than 35mm frame.

What type of lenses would you recommend for an experimental medium-to large format camera. Say, i'd like to have a wide FOV (equivalent to 28 or less mm for 35mm film) and ability to cover at least 6x9cm frame. Quality is more important than maximum aperture.
The problem with the aperture opening is, that it is small only at its location inside the lens. Behind the lens, the light needs "to fan out", to cover the larger film format. Therfor a small 35mm shutter will vignette heavily, unless the rear element of the lens in question has a diameter small enough to fit inside the shutter's opening. You then would need to place the shutter as close to the rear element as possible. That's very hard to achieve. And that is the reason, why I would recommend a Packard shutter, which you can place eitrher behind or in front of the lens. In both cases the open diameter of the Packard should be at least as big as the lens diameter.

A Packard shutter wouldn't keep you from adding masks etc. in fornt of the lens, to achieve these Lomo effects.

There are so many really good lenses for these formats. It all depends on your budget, as you may (with luck) find a good wide angle lens (65mm to 90mm) for as low as 120USD or you would need to shell out something like 900USD. It really is the same story as with SLR/DSLRs. Among the cheaper lenses you should look out for a Graflex Optar or some cheap Wollensack. You may find some Tomion lenses sold as parts of old Polaroid assemblies. These cover (as far as I know) 6x9cm, which would be sufficient for your experiemnts, perhaps and often include the shutter. I think they are available in 75mm and 105mm or so and are not bad. Price on ebay should be around 100-140USD.
. Among the better, look out for Fujinon, Nikon, or the better lines of Schneider-Kreuznach, Rodenstock etc.

I would suggest a visit to the Large Format Photography's lens forum: Lenses & Lens Accessories - Large Format Photography Forum

There is a wealth of knowledge and you may even find somebody providing a useful lens for cheap.

Ben
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