Homemade "drop slit" shutter, for Jdef and everyone else too

WOW! I did not expect so many comments so soon! Part of the reason I wanted to just send this as a PM to Jay is that I have not exposed any film with it yet. Since me and him are building shutters, we were comparing notes... I was going to post this thread as soon as I went outside and exposed something with success .

Now for the concerns:

This type of shutter (or this specific one) sort of dictates a vertical front standard. Jnannian proposed using plexiglass (painted black) as the bracket. This would provide less resistance than foam core, and slight tilts shoudn't matter as much. I have some plexi on hand, so I'll try that in due time.

I thought about springs and rubber bands, but decided to stick with this for its simplicity and lack of vibration. I can fire all I want and the front standard (homebuilt as well) won't move.

As for the light leaks, I'm not sure how well this seals light. I will add a light trap on the top portion of the bracket (some velvet or light trap foam, which I have enough of), and this should give me enough breathing room for pulling the slide, talking to the subject , and exposing the film when I want to. Also, by not putting a light trap on the bottom, I will give the slit less chances to snag. I'll have to think about this, obviously. Anyway, by painting the rear of the slit board black I should reduce the fogging by a bit.

I hadn't thought of the exposure differences in the top and bottom portions of the frame. I'll test that out, and see if its significant.

At any rate, this is very much a work in progress, and I should be a while before its reliable. But thanks for the suggestions and comments anyway, keep them coming!

And Ole,

Your focal plane shutter sounds viable, but somewhat complicated. You do realize that the slit has to travel further down than the bottom of the rear standard, and that it should be short enough not to hit the rails? I believe that a small enough slit will allow you to do this, but its a concern to have either way. Other than that, go for it!

And now downstairs for breakfast...

André

Andre R. de Avillez said:

And Ole,

Your focal plane shutter sounds viable, but somewhat complicated. You do realize that the slit has to travel further down than the bottom of the rear standard, and that it should be short enough not to hit the rails? ...

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I was thinking about a behind-the-lens shutter - almost like a rear-mounted Packard, but without the air hose hole in the front. Focal plane shutters tend to get more complicated than I care to think about, and certainly too complicated for those two "old ladies"!

Ok, right on. I guess that would be much simpler, but it leaves us with a couple of problems. The slit board would have to be long enough to cover the lens in the fully up and fully down positions, but short enough not to hit and damage the bellows. This would be very workable in those cameras you posted, if you go for relatively fast speeds, I think.

The other problem I have is interference and "jamming" as you remove the outside magnet. If pulling straight up there should be no problem, but a slight sideways drag, or forwards/backwards, and the slit board may be taken off track. I think that a sturdier bracket should help with that, though.

Sounds like a good plan to pursue...

Ole said:

I was thinking about a behind-the-lens shutter - almost like a rear-mounted Packard, but without the air hose hole in the front. Focal plane shutters tend to get more complicated than I care to think about, and certainly too complicated for those two "old ladies"!

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Um, Ole, Thornton-Pickard and, I'm sure, others used to sell roller blind shutters in small boxes intended to be mounted between lens and lens board. One of them might do for you. Or if you take T-P's hint, you could put a Packard in a thin box between board and lens.

Cheers,

Dan

Already thought of that, Dan - see the iris mount on the first one? Umm no - it doesn't show up too well in that picture... Well, it takes any lens up to 10cm (4") diameter, and holds them dead steady. A great accessory for lens coolctors and accumulaters.

I have two very nice Thornton-Pickard shutters. Unfortunately they're a lot smaller than the irid holder, and being somewhat rectangular heu won't fit in the holder either

I could use one on the second camera, but that would limit me to one or two lenses which would be a pity on a triple extensoin folding plate camera on which I've so far used lenses from 90 to 600mm!

More pics of the cameras here: Dead Link Removed

Domenico Foschi (www.dfoschisite.com) successfully mounted the focal plane shutter from a 3.25x4.25 Speed Graphic onto one of his lenboards to use behind large, fast lenses. The mid-size Graphics are cheap because of the orphaned film format. If you can find one to butcher that is in good condition, it will probably be less of a gamble (and offer more speeds) than a 100 year-old Thornton Pickard.

On the other hand, the TP shutters are so simple that they are easy to fix. I think micro-tools sell a suitable shutter material, otherwise the old manuals recommend "Good, stout Macintosh cloth".

I saw a version of the drop shutter in a Kodak publication that had color separation filters mounted in them. It was called a Harris Shutter by the author of the article. It's main use was to create the shutter artifacts in rainbow color as any moving object would be a red/green/blue blur. Moving water was really interesting shot with this. This brings up an interesting variation on the drop shutter, multiple slits. This would have an effect that could be seen on B&W film too.

Multiple stlis amounting to multiple successive exposures, right?

Not sure why we're re-inventing the packard shutter when they're readily available, cheap, and don't jiggle the camera. But you're having a grand time so, sally forth.

Right, with the moving object exposed sucessively in different places. There were a few images posted a while back of water scenes taken with several short exposures rather than one long one. The effect was quite nice.

Jim, the main factor for re-inventing the wheel, in my case, is cost. A packard shutter to fit my 305mm f/9 Nikkor would cost about 50 bucks, whereas the shutter I'm making is free since I already have all the materials around the house. It's not as smooth as a packard, or a graflex focal plane, or a Thornton Pickard, but its cheaper.

If at the end of this process I find out that this shutter is not worth it, I won't be regreting an expensive purchase or my time lost (this was all pretty quick to make, and I mess with it during my study breaks).

Anyway, I shall sally forth

Another thought.

A guy where I used to work used to work for ReCon Optical decades ago.

I asked him how the big aerial Fairchild leaf shutters could hammer so hard and not disturb the image...was it damped materials, mass of camera relative to shutter, or some other trick?

The trick gives me every confidence in our methods, that was that the mechanical shock occurred before and after the iris opens, and as long as the whole mess doesn't ring like a bell, and the mass is reasonably small compared to the rest, you don't disturb the optics!

That definitely ruled out any homebrewed stepper motor ideas that would rattle the whole time the shutter moved.

I read in Kingslake's Optical Engineering set that there was another kind of 'shooting plane' shutter, kind of like a pair of rolling rubber 'tires' engaged with a slotted plate that would hurl it across a track. They used wire brushes to damp the motion at the far end.

There's lotsa room in 8x10 & larger cameras, & the bigger, the less the shutter mass will seem!