That is what I wrote. Make the stops as shown and baffles aren't necessary. The guides do the baffling.Originally Posted by Steven Tribe
That is what I wrote. Make the stops as shown and baffles aren't necessary. The guides do the baffling.
I was thinking of flocking paper, whenever I get that far with it - Dan, thanks for mentioning Edmund Optics.
I'm still trying to get the beauty ring off the front cell to remove the limiting grub screw (for the diffusion control), as detailed in a post here by Mark Sawyer some while ago. Or rather, my brother in law is trying, he has access to a workshop and a lot more tools than I do.
I imagined I'd get it made with a flange at the back of the tube so it can be flush mounted on a 6x6 2D board - I have a packard mounted inside the front standard of my 2D. I now realize weight might be a problem mounted at the back of the tube. I'll think it over and will post back, I do appreciate the comments and information shared so far. Jac's suggestion for guides for the Waterhouse stop sounds simple and effective, I had been wondering how large a slot should be cut for stops.
Nodda Duma, the guys I've seen work out of small shops (I'm in Seoul). I was in a machine shop a month or two back, that machinist was doing lathe work manually but had a milling machine hooked up to a computer. I have no idea about CNC and CAD, don't think it will be viable. I'm still looking for my micrometer to try to figure out the threads!
To give a bit more context, the front cell is badly scratched, and the cells cost $25 with a Kodak no. 33 Anastigmat into the bargain. Shipping cost more than the bid - so I'm trying to do this on the cheap! On the other hand, I have a suspicion that even big scratches might not be such a disaster on such large cells - specially when a bit of fuzz focus is aimed at. Time will tell. I did mount the cells in a plastic pipe and held it in front of my camera. Looked ok, allowing for circumstances. Maybe I should paint that PVC tube black inside, bolt an arca swiss plate to the "barrel" and mount it on a little tripod ahead of the camera for a trial.
If you fill the scratches with india ink you'll lose a tiny bit of transmitted light and lose the flare they'd otherwise cause.
Old school machinists are hard to find here (Minnesota, USA). They are usually far more resourceful than CAD/CAM machine operators who call themselves machinists today.[...] the guys I've seen work out of small shops (I'm in Seoul). I was in a machine shop a month or two back, that machinist was doing lathe work manually but had a milling machine hooked up to a computer. I have no idea about CNC and CAD, don't think it will be viable. I'm still looking for my micrometer to try to figure out the threads!
Forget the micrometer. Google "thread gauge", and choose a modestly priced one. It will last a life-time.
Best of luck,
Jac
If you just want to test jig these cells out, and even sometimes have a OK working lens barrel, go to your local plumbing supply house and see if they have any brass/copper/ABS/PVC fittings or pipe that is close to size for a barrel... Sometimes you can find an O-ring or rubber coupler that will allow a friction fit of cells to tube, or form threads using epoxy + thread release on the cells, or have someone cut the threads, etc... You might get lucky... And coupling flanges could hold the cells, or for the lensboard mounting... Plastics wouldn't be too hard to cut/slot at home, and you will have a chance to decide if this lens is worth following through on...
For the stops, get a compass cutter from a good art store, and cut circles out of film, foil, beer cans, sheet stock, paper, card stock, whatever, and insert into slot on barrel...
Would be fun for DIY...
Steve K
He could also experiment with placing the stop in front or behind the lens.
Depending on the sizes of the pieces, I've found that used up gift cards painted flat black make good waterhouse stops, those I drilled an extra hole in and threaded a piece of string through them. I've even made conversion charts to use the same stops on several focal length lenses. Likewise non-corrugated cardboard painted black can work, but most any flat material you can cut holes in will work. I've made mine to go in front of both meniscus lenses and also a cooke triplet so I did not need to machine a slot in a huge lens barrel. I took some sheet cardboard (sort of like comes in the middle of dress shirts bought new in the US) made it into a cylinder that slips over the lens barrel (about 5" dia. in my case), made inserts for that cylinder out of foam core that I painted black, though in the US you can buy it black to start with, but that would've meant a trip to the store.... Three layers of foam core: two outer ones are ring shaped and give f8 (down from f3.6) the middle one coincides with the slot and is U shaped to hold the waterhouse stop. The stops are more of the cardboard painted flat black and give f11, 16, 22, 32, 45, and 64---that's three pieces of cardboard---they are double ended so I have fewer pieces to keep track of. I also made one with no holes to function as a "shutter" it is a little longer so I can grab it and not the stop when I want to open the aperture. None of this is as precise as what can be done in a machine shop, no, not even close, but it will give more control over images and can be made with glue/gaff tape/and an x-acto knife for almost no money into it.
Protostar flocking works well: http://www.fpi-protostar.com/hitack.htm
Super advice!
I have made countless sets of brass Waterhouse stops. I gave up making these when I purchased a Euryskop where the owner had the original brass set, but had made a duplicate set in quality black card for everyday use! Since then I have stuck to card WHS manufacture. Black card is very a standard and cheap item in almost all hobby shops.
Machine working of brass presents far more safety issues than a sharp knife.
Indian ink...looking it up I realize I've probably got the right thing at home in inkstick form, used for making Chinese characters with a brush. I'll give it a go!
The tip from Jac about cutting a section from the barrel, shortening it and using it to make guides for Waterhouse stops sounds good. I had to cut a section off to get the correct barrel length, that section was useful to centre the rear cell in the barrel. The tube I got is a bit larger than would be ideal, the next size smaller was too small. I've fixed the rear cell in place and have mounted the tube on a board using L brackets from an ironmonger store (same place I got the tube). Quite fortunately the bolts through the barrel holding it to the L brackets also hold the cell in place. I should take a photo. I need to get a bit more tube to cut down for waterhouse stop guides / baffles, maybe tomorrow if I get chance.
About Waterhouse stops, that's probably the bit I'm most confident with - I recently made some paper stops to fit in the front of an Imagon (bought with no tea strainers). I bought an adjustable paper circle cutter, a bit fiddly but it works well.
I've received the front cell back, with the beauty ring removed - at the cost of a couple of big scratches, right through the Wollensak lettering! It's now an ugly ring, matching the front cell. I have no idea what tool was used to do that...maybe better not to know some things. It doesn't look like there are any new scratches in the front cell at least. Removing the limiting screw was easy, so the diffusion control now goes from zero to extremely diffuse like in the old thread by Mark Sawyer here.
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