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Old May 28th, 2008, 11:46 PM   #1
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Low cost adapter.

Hello. I've been messing with 35mm adapters for a long time now and have a proposal. The current adapters have risen from $300.00 to $4500.00. What if somebody came along and brought back that Sub $300.00 adapter to the market. I've come up with a 3.75inx3in black aluminum case, spinning with a full 36x24mm GG, and able to adjust rotation speeds, at a cost under $100.00. NOT including an achromat. I can't give exact numbers on exactly how much light is being loss, but can say it does have film like bokeh and no visible grain, plus granting you the ability to stop up to f22, most likely...once again, not exact number. It would also harness back focus adjustment, but not XY. Back focus wouldn't be "on the fly", but the ability is there. No flip. With a new rail system coming out, if you're comfortable, you can turn your camera upside down saving the light loss of a flip unit and not having the extra gear mounted to your rods and thus less adapter to worry about. Plus, I'm fine with flipping my footage in post and having the monitor flipped upside down in the field. It even has the possibility of swapping focus screens, which I can provide at a very low cost, next to nothing. I'm also willing to post parts, plans and a how to if you have the necessary tools. I'm not "willing" to bet it's as good as other leading adapter, giving I've never used either of the major adapters, but can say, from my footage, it's very quaint. Achromats are a dime a dozen these days, so cutting the cost of having to source them would cut the adapters price significantly. I'm not looking to make a buck, but a buck or two here and there would be great for better lights, or gear, production what not, and that's why I'm going to post my adapter plans afterward upon it's completion. I'm 100% positive it can use a nikon mount, and probably a Canon eos or fd, and there's a guy who custom makes mounts so that'll create newer options of you own if ever wanted to go that route. So, all this being said, give some insight.
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Old May 29th, 2008, 06:27 AM   #2
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Rich.


With a disk groundglass, backfocus and focal plane alignment on the fly is no harder than isolation mounting a disk motor and costs only longer bolts, more nuts, three springs and a bunch of flat washers.

The only reason why I cannot do backfocus on the fly is that I am too cheap and made two of the three motor mount plate studs do double duty as studs for the rear cover.

If I used two extra bolts to hold the rear cover, drilled three clearance holes through the rear cover with grommet seals and used tubular long nuts or electrical hex threaded pillar nuts to extend through the cover for operator access, it could be done fairly easily.

Last edited by Bob Hart; May 29th, 2008 at 06:30 AM. Reason: error
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Old May 29th, 2008, 02:23 PM   #3
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so are you suggesting I try for xy adjustments? i'm not registering what your post meant.
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Old May 29th, 2008, 06:44 PM   #4
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Providing XY adjustment is a harder task.

I move the disk back and forth within the case by mounting the disk motor on a soft thick triangular polypropolene plate, securing it with three pillars bolts at each corner. Around the pillars are small stiff coil springs.

Pulling down equally on the nuts compresses the springs and adjusts the plate forward or backwards, differential adjustment of the nuts enables angular deviation to be corrected.

It is here to look at about halfway through the clip:-

http://www.youtube.com/watch?v=CnweOEEqlRY
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Old June 2nd, 2008, 09:36 PM   #5
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Bob, nice setup. Seems a bit clunky, but you also incorporated the flip with yours as well. No adding flip, your design seems more complicated than it really needs to be. And a lot of parts put together. Don't take this the wrong way. Not knocking it what-so-ever. Your using Century optics correct?

No other insight from other Dvinfoer's?

Once I get footage up, maybe I'll get more interest. Remember it'll be 3.75x3inches. That's just about the same size diameter of the DVX/HVX's lens itself. Very petite.
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Old June 3rd, 2008, 05:48 AM   #6
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Seems a bit clunky?? Is a bit clunky - and sounds a bit clunky a microsecond before the tinkling of the broken groundglass starts after it accidentally hits the deck.

The comment by a couple of pilots walking by at the Cunderdin airshow when it happened. "That sounded expensive".

The bits and pieces it is made of are mostly stuff you can find at the local hardware store so there are a lot of inconvenient workarounds. The exotic parts are the prisms and the 1.3mm optical flat the groundglass is made from and of course the Century Optics dioptre you correctly observed.

I made two versions, one with the 7+ dioptre which is shorter but has a limited view of the groundglass due to a vignette from one of the prisms. The 4+ enables a wide view of the groundglass and consequent sharper apparent resolution.

Except for the big enclosure for the disk itself, the case dimensions are about the same as your proposal for the 7+ dioptre version.
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Old June 6th, 2008, 12:29 PM   #7
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hi guys, have either of u seen the thread of another guy who made his own adaptor? i can't find it at the moment which is a bit annoying, but it was really good. He had pictures showing how to make it and posted a test (shots out in some kind of desert ranch or something) which were very impressive. I'm looking for it now coz with his instructions i feel it might be quite easy to make.
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Old June 8th, 2008, 03:27 AM   #8
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Yes, it's Edweirdo's design and it's static....so you'll have limited options with one of those. Here's the link...

http://www.dvxuser.com/V6/showthread.php?t=45972
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