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I inherited my Grandfather's beautiful Graflex Crown Graphic which he used for his entire career as a portrait photographer. (It's the picture on my avatar if you want to see it.)

Doing research on Graflex cameras I came across the Speed Graphic and the Crown Graphic. The main difference being the inclusion of a focal plane shutter in the SG.

My Crown Graphic has a leaf shutter in the lens itself. If my research is correct, I believe the Speed Graphic has both a leaf shutter and focal plane shutter. Why have two shutters on the same camera? What difference does this make?

And, in general what is the difference between a leaf shutter and focal plane shutter in function? I obviously know that the location is different! It also, clearly, makes the lens production less complicated because the lens no longer needs to contain a shutter mechanism. But, is there a photographic difference between the two?

David M
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2 Answers2

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The biggest functional difference between a leaf shutter and a focal plane shutter is the ability of a focal plane shutter to precisely allow the same amount of exposure time for the entire field of light collected at the front of the lens and to allow the practical use of faster shutter speeds.

Due to the fact that leaf shutters are open in the center longer than at the edges, the light coming through the center of the lens falls on the image plane for slightly longer periods that the light coming from the edges of the lens. This wasn't such a big issue when photography first got started and the emulsions were so low in sensitivity that typical exposure times were in minutes, rather than hundredths or even thousandths of a second! In fact, the first "shutters" were lens caps or plugs that were removed and replaced on the front of the lens by hand.

As cameras became more sensitive to light and the desired exposure times got shorter and shorter, the limitations of the leaf shutter became a more significant issue. Even so, there are still new digital cameras produced today that use leaf shutters. The designers feel, and the marketplace seems to agree, that the tradeoffs are worth it in some cases.

A focal plane shutter can be designed to begin exposure on one side of the frame and end it on the other side of the frame. This allows all parts of the frame to receive light from all parts of the lens for the same amount of time. The earliest single curtain focal plane shutters, such as those used in the Speed Graphic, had a fixed slit that passed across the focal plane. By allowing the user to select different slit widths and spring tensions for the mechanism that drove the slit across the focal plane, shutter speeds ranging from 1/10 second to 1/1000 second were possible using most of the various models of the Speed Graphic.

Why would the Speed Graphic have both a focal plane and leaf shutter? It doesn't necessarily also need a leaf shutter. Barrel lenses without a leaf shutter can be used with a Speed Graphic. The focal plane shutter is used for speed, specifically faster shutter speeds, thus the name Speed Graphic. But the camera was certainly not speedy in terms of shot to shot intervals and the operation of the FP shutter took longer to manually reset the FP curtain between shots than the operation of a leaf shutter in the lens. This may be one reason many users preferred both options. The lineup of lenses that included leaf shutters offered by lens makers could be used across both the Speed Graphic and the Crown Graphic and Century Graphic models. (The lack of a focal plane shutter allowed the Crown Graphic to be made slightly thinner which allowed use of some wider angle lenses than could be used with the Speed Graphic.)

Though not exactly applicable to your specific model, here is a link to the instructions for a c.1925 Top Handle Speed Graphic.

Michael C
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    Ive resisted putting this as an answer - a VERY important feature of a lens-mounted shutter is flash-sync.

    it is well known that a lens mounted leaf shutter can sync to 1/1000th+

     – Digital Lightcraft Jan 01 '14 at 22:47
  • Thanks! Great post! I've never gotten a satisfactory answer before! – David M Jan 01 '14 at 22:54
  • @DarkcatStudios For lenses that are designed either for sensors much smaller than 4X5 or made of modern materials and electronically controlled (or both) they can... – Michael C Jan 02 '14 at 01:31
  • "A camera-mounted FP shutter's main advantage over the competing interlens leaf shutter was ability to use a very narrow slit to offer an action stopping 1/1000 second shutter speed at a time when leaf shutters topped out at 1/250 sec." from http://en.wikipedia.org/wiki/Focal_plane_shutter – Michael C Jan 02 '14 at 01:42
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    There's also the traverse time (if I recall correctly, it was 1/10s on the fastest of the Speed Graphics, meaning that the top of the frame and the bottom saw the world a little bit differently—which is why those old-timey race cars had those neat slanted elliptical go-fast wheels) and the time it took to wind the shutter. Using the leaf shutter, wireframe finder and a Grafmatic back, you had a "burst mode" of about 6FPM. (3 FPM if you needed flash, depending on how good you were at "recycling".) –  Jan 02 '14 at 03:16
  • @StanRogers Of course there was a traverse time. Anytime the slit is narrower than the frame there will be, just as there is today. It takes a modern FP shutter 1/250 second to expose a 1/8000 second shot. Unlike today's shutters, the spring adjustment on the Speed Graphics during their heydey in the 1940-50s altered the traverse time. Some models may well have been 1/10 sec, but for the narrowest slit at 1/8th inch (on the post war 'classics') to traverse a 4 inch distance to expose at 1/1000 would have required a traverse time of about 1/30 second. – Michael C Jan 02 '14 at 03:51
  • Most of the famous elliptical race car wheel shots were taken with early models in the late 1910s and early 1920s. – Michael C Jan 02 '14 at 03:52
  • The main reason the shot to shot time was so long on the earliest models was the requirement to change the single negative film magazine between each shot. The Grafmatic film holder held six negatives, but still had to be cycled by hand. Before the shutter could be wound (with a key between each shot!) the front of the lens had to be closed to prevent the film from being exposed when the slit passed back in front of the film gate. And changing slit widths meant even more winding. – Michael C Jan 02 '14 at 04:37
  • Upon further research, even the early "Top handle" models could shoot at 1/1000 with an 1/8th inch curtain aperture (slit) width. – Michael C Jan 02 '14 at 04:38
  • @StanRogers OK. I think I understand where you were going. Are you saying one reason the leaf shutter would be used when on a Speed Graphic was if faster Tv were not needed because you could cycle the camera quicker since you didn't need to wind the FP shutter? – Michael C Jan 02 '14 at 04:42
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    That's pretty much it, Michael. Given that most of these cameras were used by newsies (with the film often developed by inspection), having the ability to properly expose for the conditions was a "nice to have" compared to "f/8 and be there — with flash". The FP shutter allowed you to take nice pictures when you had the time, but you didn't always have the time. The leaf shutter gave the equivalent of "spray and pray", which is a legitimate photojournalistic technique sometimes. –  Jan 02 '14 at 05:37
  • A lot of good stuff here, but the first paragraph is wrong.

    Leaf shutters sit in approximately the same position as the aperture. So being open longer in the center may mean some small portion of your exposure was taken more stopped down than you intended. Generally unnoticeable even at its worst, max shutter speed wide open. It does NOT change the evenness of illumination across the frame at all.

     – Roger Krueger Dec 03 '16 at 05:51
  • @RogerKrueger The opening sentence of the second paragraph doesn't say anything about evenness about illumination. It refers to the collimated light passing through the narrower part of the leaf shutter getting slightly more time than the edge rays that pass through the wider parts of the aperture created by the leaf shutter. I'll try to edit it for clarity inthat regard. – Michael C Dec 03 '16 at 11:11
  • @RogerKrueger It's most noticeable at the shortest minimum Tv, not the longest max Tv. – Michael C Dec 03 '16 at 11:15
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A focal plane shutter will, at faster speeds, be a travelling slit. That means that your aperture-selected depth of focus will be constant across the image and out-of-focus highlights will look like luminous "circles" or whatever shape the actual aperture has. Fast moving objects will get distorted since the moment of exposure differs across the plane.

A leaf shutter will basically be an opening and closing aperture. It is located at a point in the optic path where image position (of the in-focus plane) and position in the aperture plane are unrelated and the image position is rather "encoded" by the direction in which light passes the aperture at each point.

So your resulting image is an overlay of small-aperture images up to the maximum aperture size (which is held) and then back down again. For short exposure times, your out-of-focus highlight shape is then not as much a luminous disk but more like a "luminous ball" since it gets darker on the outside. Also you don't get the kind of distortion for fast-moving objects. There is a limit to the combination of large aperture and short exposure time though. Since the distances to cover are quite smaller than in the focal plane, however, the flash sync time (where full-area exposure is required) can usually be shorter.