A variation of Tom Hoskinson's polarfleece lens sock, my wife sewed a circular piece of black foam core into the closed end of sock. This extra rigidity adds protection & ease of removing/replacing lens sock. She also sewed a hemline around open end, again for rigidity. I have two barrell lens for my 8X10 and these lens socks make convenient shutters.
van Huyck Photo
"Progress is only a direction, and it's often the wrong direction"
My only barrel lens is a Goerz Artar from that Galli guy and all I do is stop it down tf F/90 and use a bit of black poly sheet in the waterhouse slot for a shutter leaf
1) set up camera and insert film holder
2) insert shutter leaf into WH slot
3) pull dark slide, pull WH shutter leaf, count and reinsert shutter leaf
4) reinsert dark slide
Process and get this :
Also, once you get into the multi-second exposure times, a little vibration at the beginning and end of the exposure won't show.
Not necessarily so. Insert film holder. Remove dark slide. Hold dark slide close to the lens. Remove lens cap. When vibrations subside, start exposure with dark slide. End exposure with dark slide. Replace lens cap. Insert dark slide in film holder. With strong frontal light on the subject, a black velvet covered cardboard may work better than the dark slide for making the exposure. The dark slide (or velvet) should be moved quickly to begin and end the exposure to reduce the abberation induced by an object near the lens. When using the dark slide as a shutter, it can also be used as the cheap photographer's graduated filter to darken skies, etc.
Originally Posted by Flauvius
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Does anyone know why Sinar's auto shutter could not be redesigned and fabricated to accept lenses with rear elements whose outside diameters are greater than 82.65mm? In this regard, the largest rear lens element that will fit into a Sinar auto shutter is 82.65mm.
Mechanically, my concern is whether the time required for either a curtain or iris shutter to open and close, and to assure speeds from 1/4 of a second through 20 minunets, would be incompatible with the large diameter of lenses attractive to large and ultra large photographers? Indeed, apart from a Sinar auto shutter, I can visualize a rather simple clock like device that could be used with any lens; some thing like an iris mount with a shutter in a aluminum housing.
Unfortunately, I never learned to make mechanical drawings and am unable to express myself more precisely. However, given the cost of large and ultra large format film and processing, I would think that someone other than Sinar has addressed this issue of a device to assure accurate exposures with barrel lenses and whose rear elements are larger than 82.65mm.
In short, why can't an accurate universal shutter for large barrel lenses be made?
Sure it can be made, but be realistic... How big of a market is there for this? I doubt that any of the big shutter makers would think that it was commercially viable.
Originally Posted by Flauvius
Having said that, it wouldn't be too difficult to make an electronic timing control circuit for an electrically operated Packard (they're not all air operated).
Some people are like Slinkies. They're really good for nothing, but they still bring a smile to your face when you push them down a flight of stairs.
large leaf shutters
If you've ever played with an aerial shutter with a 4" opening, and see how much force is required for a fast shutter speed (I understand most of you don't need/want a fast shutter), it's a reminder that the physics involved get imposing.
If you increase the required opening, the mass, the acceleration, the energy required by springs, etc increase dramatically. That said, Packards do what they so well because they aren't trying to race tortoises.
Back to the martketing question - important point...a leaf shutter with all that mechanical mess for slow speeds only sure seems like a diminishing market - sure, I'd love one too, but it'll have to come out of my garage and would also serve to chop the ends off cigars...keep fingers out.
Everyone seems to despise electric-powered shutters so much...if a camera already weighs more than my backpack, I'm not too worried about the added weight of a battery. I like the idea of a motorized focal plane shutter, and recycled hard drive mechanisms look like a good option. Ugly isn't a problem for my tastes.
JIm Galli's method works very well. With a little practice it is not too difficult to obtain shutter times of 1/25 or maybe faster. 1/2 second or longer become a piece of cake with a few tries.
I use soft focus lenses wide open most of the time, and those which do not have a shutter are used with this method.
If in very bright light, I use neutral density filters so I don't have to have fast, accurate shutter speeds.
I also have built a guillotine shutter which can be mounted on the front of barrel lenses. The only problem with it is that it is a single speed, 1/45 second. I have not figured a way to build one with varying times, but I am working on it.
[FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]
Originally Posted by Jim Noel
If your guillotine shutter is of the type that has a falling blade with a horizontal slit that travels (falls) across the face of the lens for exposure, then the way to increase exposure (slower speed) is to make the slit wider and to decrease exposure (faster speed) is to narrow the slit. The downside of this is that you need to have a guillotine knife with a different width of slit for each different speed.
Is this what you were asking about?