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#31
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Crown vs. Speed Graphics [was Zeiss Ikonta Shutter - Rapid and Synchro - both have flash?]
"David Nebenzahl" wrote in message s.com... On 3/2/2008 3:35 PM Richard Knoppow spake thus: The usual reason for rejecting the Speed Graphic is weight, the Crown is lighter and has a shallower box. However I do find the focal plane shutter to be useful especially for barrel type lenses. Also, Crown Graphics, originally the economy model, are often more expensive than the Speed Graphic on the used market. Either will give you a taste for LF although they have very limited movements and limited bellows draw. Graphic cameras were intended to be hand held and offer a way of getting a large negative for situations where a tripod can not be used. (Like that famous picture of Jack Ruby shooting Oswald, where at least one handheld Graflex is visible.) Since we're on the subject, yes, I should have mentioned about the barrel lenses, though these are more rare than lenses with shutters. Questions: 1. I didn't know that Crowns go for more than Speeds. Is this because people like the former better, or for other reasons (see question #2)? 2. Do Speed Graphics typically have working focal-plane shutters? I would have thought that because of the complexity of this mechanism, it might be likely to fail in cameras of this age. (I've never even seen a Speed Graphic up close and personal.) I don't know what prices are like now but a few years ago Crown Graphics were going for more than Speed Graphics. One has to check the shutter, maybe even to make sure its still there (some idiots like to remove them). Actually, the Graflex shutter mechanism is very simple and not easily broken. The shutter curtain in the later cameras appears to be made of some synthetic with quite long life. Usually they need only to be lubricated. I don't remember if the Graflex site has a diagram of the shutter. If so it will make things obvious. The first shutter used by Folmer & Schwing on the Graflex SLR was a self capping shutter but it proved too elaborate and not reliable so, within some very short time, they came up with the simplified shutter used forever after. This consists of a rubberized cloth curtain with five slits of varying length on it. The curtain runs between two spring loaded rollers, quite similar to the rollers used for window shades. The lower roller has a spring which can be adjusted by winding it. This changes the travel time of the shutter. The upper roller has a fixed spring with enough tension to maintain the curtain taught. The speed is set by winding the curtain up to the upper roller to the slit desired. The spring on the lower roller is wound to the desired tension. There is a chart on the camera showing the shutter speeds resulting from each combination of slit width and spring tension. There is enough blank space between each slit and the next to cap the film. When the shutter is tripped the curtain winds down one slit and stops. You must then put the dark slide back in the holder because when the shutter is wound up again it pulls the slit back over the focal plane. If you trip the shutter a second time without winding it back the _next_ slit will go over the film. Because the curtain accelerates as it travels the speeds are not constant from top to bottom. The amount of change varies with the tension and slit size being greatest for the highest speeds where it can be nearly 2:1 over the travel. At one time F&S advertized this as an advantage for Graflex cameras because it would darken the sky in a landscape. The last of these shutters, the one used on 4x5 Pacemaker Speed Graphics, had a flywheel to control the speeds on the low range which resulted in considerably more uniform exposure. The _effective_ speed of a focal plane shutter is a function of the distance between the shutter slit and the film and the focal length of the lens. Actually the angle of the cone of light emitted by the lens so it varies with the focus. In the Graflex/Speed Graphic shutter the efficiency is not very high so there is considerable variation plus the higher speeds can not be directly measured with a shutter tester. The speeds will read low. The speed can be read more accurately by adjusting the intensity of the light at the tester so that its just one stop more than the point at which the tester stops counting. One then reads the light at the half intensity points. For Speed Graphics the measured speed of the highest speed, 1/1000 second will be only about 1/800th if this method is not used. I've found several SGs where the shutter tension adjustment had been wound very tight to get the top speed to read 1/1000 on a total open time tester. This, of course, will throw off all the speeds. The shutter in the Pacemaker Speed Graphic and the Super-D Graflex are pretty accurate, most of the 25 speeds listed on the charts for other Graphic and Graflex cameras have a good deal of wishful thinking in them. Like 35mm rangefinder cameras its possible to burn a hole in the focal plane shutter by pointing the camera at the sun with the shutter wound. Note also that careful adjustment of the stops for the shutter is necessary to avoid shutter bounce at the end of travel. This can lead to a strip of double exposure at the bottom of the negative. It is a more difficult problem in Graflex cameras with rotating backs because of the about 20% longer shutter travel needed to cover the film lengthwise. Once a Graphic or Graflex FP shutter is set up and lubed correctly it won't need attention for many years. There have been more elaborate FP shutters on 4x5 cameras. One is the shutter found on some Busch Pressman cameras. These, I think were intended to meet the military spec for the Speed Graphic. These are self-capping shutters cut out the light when they are re-wound) and have more accurate and uniform speeds. I've never seen a drawing of the mechanism and have, in fact, only ever seen one camera with this shutter. They were advertized along around the mid 1950's. The other elaborate shutter is the one used on the ICA, later Zeiss-Ikon Mirroflex. This is a gear train regulated shutter with some resemblance to the shutter in the Contax camera. Also self-capping and quite accurate. The main problem with these is rubber rot necessitating replacement of the shutter curtains. I am quite sure this is much more than anyone ever wanted to know about these shutters. -- --- Richard Knoppow Los Angeles, CA, USA |
#32
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Zeiss Ikonta Shutter - Rapid and Synchro - both have flash?
On Mar 2, 4:29 pm, David Nebenzahl wrote:
On 3/2/2008 11:39 AM jch spake thus: David Nebenzahl wrote: Like LF cameras, used enlargers are now going very cheaply, either locally available or on a certain little web auction site. (If you're in an area served by Craigslist, check there.) A 4x5 enlarger doesn't take up that much more room than your present one. Fair enough. Have you any recommendations for enlargers? I have _never_ looked at MF or LF enlargers. Are they mainly condenser types, or the diffusion types? For example, the condenser in the Durst is already pretty massive and heavy. I shall also have to design the enlarger base surface for multiple enlarger mounts. The usual: Omega (D2), Beseler, etc. Shoot: I just saw a Beseler 4x5 enlarger, at the Oakland Museum White Elephant sale, going for about $25 (no lens, but otherwise looked complete). These are all condenser types. In the event that you need parts (which is likely, since many enlargers will come without needed parts, like negative carriers, lensboards, etc.), you can find these on that small little on-line auction site. Likewise, lenses (including really good ones, like Componons, Nikkors and Rodenstocks) are going for cheap. Hint: get the next-size-up lens for your format if you don't need to make big enlargements; for instance, get a 165 mm instead of a 135 mm lens for 4x5. This will give you better corner-to-corner sharpness. Older enlargers, like the Elwoods (mostly found in 5x7 size like mine) are diffusion types. The baseboards are a little larger than your Durst, but not by much. The Elwood lamp is a strange mixture. Its not really diffusing because it concentrates the light using a polished parabolic reflector. The lamp itself is diffuse, a large size opal lamp, so the source is not specular. In addition, there is a rough, sandblasted, ground glass light equalizer to even out the center to edge illumination. This glass has surface which is nearly clear at the edges and becomes progressively more diffuse toward the center. I am not sure how this compares with the sort of partially diffusing condenser lamphouse found on enlargers such as the Omega, but its probably similar. There are enlargers with true diffusion sources. Most cold light sources are very diffuse as are most color head types which have light integrator boxes, essentially diffusers. Few enlargers have truly specular sources. A few point source lamps were supplied for special purposes such as making very large prints or printing from microfilm where the highest possible resolution and edge sharpness is necessary. For the most part these sources are impractical for general use because they exaggerate flaws in the film so much. Practical lamphouses vary about one paper grade overall for black and white film with silver images. The amount of variation in effective density with the relative diffusion of the light source depends on the particle size of the image. Coarse grain silver images have the most and dye images have the least. This is known as Callier effect. For color films and chromogenic B&W films the effect is nearly nil. -- Richard Knoppow Los Angeles, CA, USA |
#33
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Zeiss Ikonta Shutter - Rapid and Synchro - both have flash?
On Feb 27, 5:33 am, jjs wrote:
(Asking here because of the great expertise here. I also posted to the MF group.) It was/is my understanding that the old Zeiss Super Ikonta 'flash' shutter was called a Synchro, and that the Rapid and other shutters had no flash terminal. However, on that big auction site a fellow has one with a Rapid shutter and claims that it has a flash terminal. He says it is just next to the shutter cocking lever. Is this atypical or am I just flat wrong? It's item #230226141947 begin 666 rtCurve.gif M1TE&.#EA" `(`)$``/___^_O[\[.SO___R'Y! 44``,`+ `````(``@```(1 35( `` ` end In one of my replies to this thread I mentioned a web site I could not find that had historical information about shutters on it. I've now found it. http://www.kamera-geschichte.de/files/verschluss1_d.htm This has a time line of both Deckel and Gauthier (Pronto, Prontor, etc) shutters with illustrations. It should help answer this question. Richard Knoppow |
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