Exposure With Barrel Lenses

[Flauvius]

Apart from "winging-it" with a Packard shutter, how are the Jim Gallis of the world making decent images with barrel lenses? Given the burgeoning interest in ultra large format and its attendant expense, I am amazed that there is so little information on this subject.

Flauvius

 

[glennfromwy]

While ULF isn't my cup-o-tea, I do occasionally use barrel lenses. My opinion is that, since small stops are usually the norm, neutral density and/or other filters are easy to use to get exposure into the one second or more range. No shutter necessary, just a lens cap. Exposures of one or more seconds are easy to accurately time, too.

 

[Flauvius]

In years past, lens caps worked with very slow film and reciprocity was not an issue as it is today. Also, the use of a lens cap will certainly introduce camera shake which is more pronounced in larger formats.

So what is it that those of us who use lenses in conventional shutters are missing?

Flauvius

 

[removed account4]

i use a slr ( series d ) + speed graphic, with working focal plane shutters, so i really don't need to worry about a shutter with my lens ...

 

[MattCarey]

Jim posted something a while back about using some darkslides as a makshift shutter. It sounded like it should be easy and useful.

Matt

 

[df cardwell]

Also, the use of a lens cap will certainly introduce camera shake which is more pronounced in larger formats.

So what is it that those of us who use lenses in conventional shutters are missing?

Flauvius

Technique.

A lens cap shutter doesn't HAVE to induce motion.

My Deardorff doesn't mind it a bit.

And a Packard, at it's 1/15 - 1/20 of a second, is more repeatable than a new Copal. ( don't scream until you try it )

Say a sheet of TMY, on a bright sunny day, wants... 1/250 @ f/16.

1/250 @ f/16 = 1/60 @ f/32 = 1/15 (Packard Shutter) and 2 stops of filtration. Pretty easy.

With an unshuttered lens, I like to aim for a 1 second exposure. With a long straight line like TMY, a stop extra exposure isn't noticeable, so I only need to hit between 1 and 3 seconds and that's easy.

60/30/15/8/4/2/1 = 7 stops = easy with a couple ND filters.

It's even easier in lower light. With older films, with serious reciprocity compensation, you can make it work FOR you.

A 1 second exposure needs an additional 1 stop, or 2 seconds.
A 5 second exposure wants a stop and a half extra, or 7 1/2 seconds.

SO, if you want a one second exposure, reciprocity failure lets you land someplace between 2 and 5 seconds, and you are exceeding accurate.

Again, the whole business of working with a cap, or sock, or hat, or whatever... is a matter of simple technique. Easy. Thank goodness.

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[bobfowler]

Apart from "winging-it" with a Packard shutter, how are the Jim Gallis of the world making decent images with barrel lenses? Given the burgeoning interest in ultra large format and its attendant expense, I am amazed that there is so little information on this subject.

Flauvius

Packard shutters aren't exactly "winging it". I'm using them with Artar, APO Nikkor, Ektanon, and of course with an acquired from Jim Galli Petzval. Now I do have a lot of lenses in modern, clockwork shutters, but I don't think I ever use a shutter speed faster than 1/30 sec very often. With a bit of practice, getting reasonably accurate slower speeds (1/4, 1/8) is quite easy.

 

[Ole]

Slow film, small stops, low light and a hat.

 

[Tom Hoskinson]

Take a look at my gallery and my Polarfleece sock shutter:

/www.apug.org/gallery/showphoto.php?photo=1767&cat=500&ppuser=1578

Small f stops and shutter speeds ranging from 2 seconds and longer with no camera shake.

 

[David H. Bebbington]

I have found my Day shutter very handy - clamps on any lens up to about 3 1/2" diameter, gives good bulb-timed speeds to about 1/8 plus an instantaneous speed of about 1/30 and is flash-synced. They were advertised in Britain until at least the mid-1950s, don't see many these days.

 

[doughowk]

Lens Sock

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.

 

[John Bartley]

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 :

 

[TheFlyingCamera]

Also, once you get into the multi-second exposure times, a little vibration at the beginning and end of the exposure won't show.

 

[Jim Jones]

. . . Also, the use of a lens cap will certainly introduce camera shake which is more pronounced in larger formats.
Flauvius

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.

 

[matt miller]

(there was a url link here which no longer exists)

this looks like it would work wonderfully.

 

[Flauvius]

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?

Regards,

Flauvius

 

[bobfowler]

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?

Regards,

Flauvius

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.

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).

 

[Murray@uptowngallery]

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 Noel]

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.

Jim

 

[John Bartley]

..... 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.

Jim

Jim,

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?

cheers

 

[Jim Noel]

I realize what you say about slit width.

I am trying to make something like a Graflex shutter curtain with several, at least 3, different sized slots on a single guillotine. Making the guillotine is not a problem, my problem is how to stop it at the bottom when using anything other than the top slit.

Jim

 

[Dan Fromm]

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[John Bartley]

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Exactly, but it makes for a very long and possibly very wide slide depending on how many choices are wanted. Still, Dans suggestion is absolutely practical and frighteningly simple - nice one Dan !!

 

[Dan Fromm]

Come to think of it, a moveable peg on the guillotine would work as well as a stepped guillotine.

 

[Joe VanCleave]

re: Guillotine Shutters

For a gravity-powered guillotine shutter, the problem is that the speed changes when the camera is tilted up or down from horizontal.

A better idea for a homebuilt guillotine shutter is spring powered, with the shutter blades travelling horizontal rather than vertical, so gravity isn't a factor. The shutter can be built with two leafs that sandwich together, with a variable-width slot adjustment that's adjusted before-hand for the required exposure time. Include calibration lines on the leafs for the various exposure times.

And, as alluded to earlier, any large moving mass will present problems with camera movement, especially if the wide-open lens aperture is big, requiring a large shutter. Although I don't see problems with my Speed Graphic's curtain shutter. Perhaps a flimsy field camera with poor front standard support would present a problem with vibration.

Sounds like someone needs to cobble together one of these and try it out!