SLR with leaf shutter?

[connealy]

Just to keep things in perspective, here a few shots from my Contaflex I <i>before</i> the CLA:

 

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[winfried_buechsenschuetz1]

"Bessamatic/Ultramatic, Paxette Reflex, Retina Reflex and Ambiflex all featured interchangeable lenses with a leaf shutter mount -- and all were deliberatedly designed to be incompatible to each other."

 

As far as these cameras have Compur shutters, the bayonets of their lens can be made more or less compatible. The basic design of the bayonet is always the same (designed by the shutter manufacturer), but some notches and tabs were added by some manufacturers just to sell their own lenses to the camera owners.

 

I think Rick Oleson has some instructions on his fabulous website how to convert Compur mount lenses.

 

BTW, I once owned a (fixed-lens) Kowa and I have a Topcon Uni with a complete set of lenses (including a third-party tele converter and close-up lenses for the 200mm lens which focusses down to 5m/15ft. only). I found the Topcon easier to fix than the Kowa. The Kowa have a coupling system between the lens settings and the meter readings which gets out of sync as soon as you lift the front plate to get access to the shutter, and it is not easy to get the coupling system back together again. The Topcon Uni was running right from the start (bought it on a flea market) and the Kowa worked flawless after cleaning the shutter gears (slow speeds were gummed).

[john carter]

Here is a photo of a Topcon Unirex. I still use and have a 28mm and a 135mm to go with it. $14.50 each on Ebay (for the lenses). I ran a roll thru it last weekend. As been posted the only advantage is syn to 500th.

 

http://www.photo.net/photo/4301569

[chuck_foreman1]

Hi All,

 

I'm enjoying the discussion. For any german readers a releted article I read recently from Frank Mechelhoff titled "West German Camera makers: How they lost to Japan" shows how these were cutting edge designs that were widely respected but gave way to the easier

to build and develop/exploit SLR. He had these cutaways views

 

FYR<div></div>

[chuck_foreman1]

Hi All,

 

Another cutaway view from Frank Mechelhoff's article titled "West German Camera makers: How they lost to Japan"

 

FYR<div></div>

[richard_oleson]

Wow.

 

"The focal plane shutter presents so many problems and challenges to the camera designer and there seem to be so many great benefits to a leaf shutter design"

 

I'm not sure, but I think that might be the most inverse-logic sentence that I've read relating to cameras since Pop Photo's 1946 prediction of masses of Japanese rushing to buy American cameras.

 

In a focal plane SLR release sequence, the mirror goes up and the shutter travels... the mirror may or may not come back down. In a leaf shutter SLR, the shutter closes, the lens stops down, the mirror goes up, the light baffle goes up, the shutter opens and then the shutter closes again... if you have an instant return mirror, the light baffle has to close again and the shutter and diaphragm both reopen. Based on word count alone the leaf shutter approach is much more of a challenge. Add interchangeable lenses and you add the challenge of passing the light bundle of every lens in your kit through a 20mm diameter hole in the shutter (ever wonder why a Bessamatic's 135 lens won't focus closer than 13 feet, or why a Kowa's 135mm f/4 lens has a 67mm filter size?)

 

Add to all this a West German coupled light meter system and you've got a mechanical system that's like a self-guiding our of Byzantium.

 

The net benefit for all this: flash synch to 1/500 second.

 

All leaf shutter SLRs are interesting machines, and some (notably the Kowas) are very well designed and quite reliable. But relieving the designer of 'problems and challenges' was NEVER one of their virtues.

[ben_hutcherson]

Are there any 35mm leaf shutter SLRs which have the shutter as part of the interchangeable lens design like Hasselblad and everyone else does with their medium format SLRs?

 

It seems as though this would alleviate the problem of having all lenses have the same size rear element, at the expense of more connections between the camera and the lens.

 

Is that just one of those things which works in larger formats but doesn't scale down very well to smaller formats?

[david_m]

Topcon Unirex, Uni and Auto 100 has a sector shutter, not a leaf shutter.

[richard_oleson]

I can't think of any, Ben. I think the added cost of having to buy a shutter every time you want to add a lens was probably prohibitive in the price class where 35mm leaf shutter SLRs were able to compete. Bulk would probably have been an issue too, you can't easily scale a shutter down to make it fit within, say, a 50/1.8 lens barrel without leaving a noticeable bulge. In medium format there was more real estate and more money to work with .... as well as a professional user who was more willing and able to learn the correct operating sequence for the various linkages (shutter cocked/mirror cocked etc) to make it all work right without breaking something. Your average 35mm snapshooter can't usually handle much of that, and the 35mm press shooters don't have time.

[winfried_buechsenschuetz1]

"Topcon Unirex, Uni and Auto 100 has a sector shutter, not a leaf shutter."

 

I think I read this before - maybe from the same author, and it is as false as it used to be. At least the sample of Topcon Uni I have clearly shows 5 shutter blades. The shutter is made by Copal, they never made sector shutters.

 

I just looked it up - yes, it was David M. who wrote this years ago. Did he never have a look at his camera with the lens off????

[winfried_buechsenschuetz1]

Maybe David M. is a bit confused by the extra flap behind the mirror of the Topcon leaf shutter SLRs. This flap actually blocks light since the mirror does not reach all down to the bottom of the camera, but it has nothing to do with the shutter operation itself. Also, it is the base plate for the light meter cell which is located behind the mirror (on Kowa SLRs it is located in the prism).

 

The extra flap/blind flips up and down in sync with the mirror, but exposure time is controlled by the leaf shutter only.

 

Also, sector shutters are suitable for slower speeds only, the Exas are limited to 1/150 sec. The Topcons reach 1/300 (and quite precisely, I have checked it).

[pico]

<b>ocean physics</b><i>the faster speeds they do offer are inaccurate and inconsistent

when used at different aperture.</i><p>

Is that some kind of Atlantean physics? Can you explain?<p>

BTW, there was a Kodak shutter marked at 1/1000th of a second, but it wasn't quite that fast

and it was also a bit unreliable.

[ben_hutcherson]

Thanks Rick, that makes sense. I've never used a Hassie or other leaf-shuttered medium format camera, but I understand that they can be a bit fiddly with mounting and dismounting, especially if you don't know exactly what you're doing.

[winfried_buechsenschuetz1]

"pico digoliardi, Apr 27, 2007; 09:44 a.m.

 

ocean physicsthe faster speeds they do offer are inaccurate and inconsistent when used at different aperture.

 

Is that some kind of Atlantean physics? Can you explain?"

 

It makes sense when you take into account that the leaves of a leaf shutter do not open and close at light speeed. Usually it takes 1...2 millisec for a shutter to open and the same time to close again. Well, how come that a shutter can run at 1/500 sec = 2.0millisec? The shutter speed is measured from the time the shutter is half open until it is half closed again.

 

Of course the exposure time for a small (pinhole) opening of the shutter is much longer - just add the opening and closing time. When the aperture is small (say, f/22), it is this small opening (with extended exposure time) which matters. If the aperture is fully open, it is just the mean value between the "pinhole opening time" and the "fully open time" which matters (since the film collects light over the full period and will average exposure intensity over time), and the effective shutter speed is faster or, in other words, exposure time is shorter.

 

However, focal plane shutters cannot bypass the laws of physics, either. They will distort objects running very fast in the direction of the shutter curtains. This can be seen on old newspaper photos of car races: sometimes the wheels are rather oval due to this distortion. Back then total travelling time of a shutter curtain was around 1/25 sec, it has been speeded up since to 1/125 sec and thus this effect is less noticeable on comtemporary cameras.

[pico]

<i>It makes sense when you take into account that the leaves of a leaf shutter do not open

and close at light speeed.</i><p>

I think you miss the fact that there is a lens involved: the light is distributed over the whole

focal plane during every position of the leaf shutter.

[dan_fromm2]

Pico, its a question of shutter efficiency.

 

Y'know, by 1970 when I first went shopping for an SLR Japanese SLRs with focal plane shutters, many but not all with the Copal square shutter, pretty well dominated the market. SLRs with leaf shutters were seen as much more limited and basically out-dated. None of them seemed a system camera with a system to match, e.g., Exakta or Nikon F or, for that matter, even Konica AR. They all embodied the wrong compromises.

 

By then european camera manufacturers were dying because of competition from Japan. They couldn't compete on price and not all of them could compete on quality. Just think of the King Regula Reflex 2000 CTL. Pretty camera, nice idea, much too fragile.

[richard_oleson]

No leaf shutter can be considered accurate and consistent in speed at its highest speed, whatever that speed is.

 

The reason is this: At its highest speed, the blades are constantly in motion, there is essentially no measurable time span during which the lens is fully open. Therefore, the effective speed is never the actual open (or more accurately, partly-open) duration but it is rather calculated to represent the equivalent amount of light that would have passed through it if it had been fully open. At 1/500, the shutter may actually take 1/250 second from the time it first cracks open until it is completely closed again, but since it was never FULLY open it passes only 1/500 second worth of light.

 

But this assumes that you are at full aperture. If you stop the lens down to, say, f/16 and fire the shutter again at the same speed, when the shutter begins to open from the center out, it almost immediately exposes the entire small circle of the f/16 diaphragm. From this point on, the working aperture is fully open while the blades continue to open and close, until they have again closed down to the diameter of the small circle.

 

So: a perfectly accurate and calibrated leaf shutter will give an exposure equivalent to 1/500 when set at 1/500, ONLY when the lens is wide open. When fully stopped down, the same perfect shutter will give an exposure equivalent to closer to 1/250, and at every intermediate aperture you will get a different intermediate speed in proportion to the aperture.

[winfried_buechsenschuetz1]

"I think you miss the fact that there is a lens involved: the light is distributed over the whole focal plane during every position of the leaf shutter."

 

This is true, but the amount of light energy going to the shutter is not constant during the opening and closing time. It is more or less like a diaphragm opening and closing very fast. It is quite obvious that only a fraction of the light can be transmitted when the diaphragm (or shutter) blades are half open or half closed.

[gib]

I have used a Contaflex super B and a Bessamatic, great cameras, great lenses. Wouldnt part with them.

[patrick j dempsey]

Richard... I was speaking about the leaf shutters themselves and not the entire SLR mechanisms... I consider SLRS themselves to be really complicated machines and especially the focal plane shutters.... and was wondering if there had ever been a simpler version. Im a big fan of TLRs and I consider it to really be the best of both worlds. The benifits I was speaking of include the durability and reliability of leaf shutters as well as the relative simplicity in design of the shutter itself. I guess all the extra mechanisms to allow for an SLR really outweigh these advantages. Most of my leaf-shutter cameras are pretty ancient and dont have speeds over 1/250th and I usually shoot wide open most of the time so I have never encountered the speed issues you mention. I do have a Mamiya C220 which has 1/500th top speed... Ill have to take your words into consideration when shooting on the fast-end of the scale! Fascinating!

[www.adimeo.net]

My dad had a Kowa seTr, purchased in or around 1968. I recently discovered it in the house. The shutter jammed twice and after that, he gave up on it. I did not realize until now that it had a leaf shutter. Apparently, the leaf shutter combined with the mirror mechanism was overly complex with too many moving parts, resulting in reliability problems. The availability of flash synch at all shutter speeds is outweighed by these reliability issues. If the leaf shutter SLR was a successful design, more companies would have made them. It is interesting that Kowa was never a major player in the 35mm SLR market.

[ed_farmer]

I was wondering if there had been any SLRs made with leaf shutters? The focal

plane shutter presents so many problems and challenges to the camera designer

and there seem to be so many great benefits to a leaf shutter design. Does

anyone know of cameras like this and have information on how they might have

functioned? Would there have been a dark-slide or light baffle behind the

mirror to block light during focusing? I could see a very slow version being a

manually actuated mirror and light-baffle... where you would focus on T, and

then close the shutter... flip up the mirror/light-baffle and then make your

exposure... flipping the mirror/light baffle back down to compose the next shot.

Any thoughts?

 

Yes . . . There have been MANY SLR's with leaf shutters and/or leaf shutter option. While the focal plane shutter IS an engineering marvel there are also a great number of benefits to them as well. Leaf shutter don't have speeds as high as FP shutters. This is because the same blades have to open and then reverse direction to close. Fast FP shutters travel as a slit to get high speeds (I believe Minolta went as high as 1/12000. You also only needed one shutter for your system. Generally, LF shutters live between the glass elements of your lens and each lens has to have it's own shutter. This is not only expensive but prevents predictable exposures from one lens to another.

 

There is no need for a "dark-slide or light baffle" behind the mirror. The mirror itself protected the film in many models. The "very slow version" that you describe is what is done with most view cameras.

[John Seaman]

I've never had a working leaf shutter SLR. It seems odd that having flash synch available at all speeds was seen as so important around 1960. The German makers in particular seemed obsessed with this feature, at their significant detriment in terms of backing a costly, unreliable dead end technology.

[ed_farmer]

I've never had a working leaf shutter SLR. It seems odd that having flash synch available at all speeds was seen as so important around 1960. The German makers in particular seemed obsessed with this feature, at their significant detriment in terms of backing a costly, unreliable dead end technology.

 

It wasn't so much that leaf shutter could sync at all speeds as it was that FP shutters of the time could only sync at 1/30 or 1/60, not the more modern 250. Also that they were trying to sync with flash bulbs, not electronic flash. Bulbs have a much longer "bloom" when fired and required longer shutter speeds than electronic flash.

[JDMvW]

ed has it precisely. 'home' use at the time meant flashbulbs.

Not only did many of the traditional focal-plane shutter SLR makers try to make one of these, they all pretty much did it at the same time

 

some discussion of this in my posting on the Zeiss/Pentacon Jena Pentina at Pentina - resurrection and life