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Old October 24th, 2004, 07:26 AM   #241
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great work dogus. your design looks great.

could you tell me the diameter of your eccentric shaft .

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Old October 24th, 2004, 08:17 AM   #242
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the outer diameter is 10mm and inner is 5 mm..which makes a 2.5 mm diamterer of motion...
( the measurments of the mill on dodo35-4.jpg picture)
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Old October 24th, 2004, 09:57 AM   #243
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so it looks like the inner diameter of the ball bearing is 10mm . what would the outtside of the ball bearing be .
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Old October 24th, 2004, 10:17 AM   #244
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the diameters are inner outer

big bearing ... 10 19
small bearing .. 5 16
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Old October 24th, 2004, 12:28 PM   #245
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Jim, Richard, Dogus, Les, Brett, etc., etc... i've been off the thread for a bit but you all have great new ideas and links to quality parts guys that i couldn't find previously. i'm very impressed. a couple of questions...

Dogus, what type of motor are you using in your schematics, looks like a low voltage Radio Shack type motor(?)

Jim, as far as parts, i'm looking at 52mm fittings, it would only seem right that the 2" lens tubes from Thorlabs you showed probably would work on 52, but it might be you are using 49mm type of housings for the inside(?)

Richard, also thanks for your great efforts also and your recco's and links to boot. i'm having some trouble visually seeing how the "oscilating glass" works, but i'm VERY interested in seeing if i can improve sturdyness and quality even more. would it be possible if you could give me another example that might help me understand more.

Les, i've had some success with the lens adapters i've made so far, i am also interested in the quality you've achieved so far, could you send me a link to your video tests so far??? please send to dinor@hotmail.com

tkx all...
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Old October 24th, 2004, 12:54 PM   #246
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Dino, link emailed. Send me your comments.

Dogus: I can't wait to see your sample video too, gook luck with your project! Please keep the video high quality as far as compression, if and when you post. Stills of the video are useless to see whats going on, as you know.
-Les
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Old October 24th, 2004, 12:58 PM   #247
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I spent some time with this. And I think this is going to work perfectly. great job
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Old October 24th, 2004, 01:19 PM   #248
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Quote:
Jim, as far as parts, i'm looking at 52mm fittings, it would only seem right that the 2" lens tubes from Thorlabs you showed probably would work on 52, but it might be you are using 49mm type of housings for the inside(?)
Dino,

I'm unsure about the fittings of the parts. I've gone ahead and ordered the coupling because my best guess is that:

Given that the tubing is 2", with an interior diameter of 50.08mm, threaded on the inside, I will at the very least need an externally threaded coupler to attach the tubing to a filter or step-down ring. That said, 49mm is the closest from among the choices of standardized camera parts to 50mm. So, it's my best guess that this setup should work. Consequently, I'd also bet that 52mm parts will be too big -- nevermind the fact that the tubing is threaded on the interior side.

My parts have already shipped, and are due to arrive on Tuesday -- I'll let all here know right away as to my success or incorrect guesses :D

- jim
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Realism, anyway, is never exactly the same as reality, and in the cinema it is of necessity faked. -- J-L G
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Old October 24th, 2004, 01:59 PM   #249
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c-mount

I found a c- mount adapter for the 1 inch tube but don't know about the 2 inch tube yet.

http://www.thorlabs.com/ProductDetai...roduct_ID=1454
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Old October 24th, 2004, 03:54 PM   #250
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Medium format adapter

Dino great geat work! We're on the same page - design and medium format wise. I've been pulling my hair out trying to find offset shafts like yours. You said you had them custom milled. If possible, could you quote me a price to have four more made and sent to me? Drop me a email and I'll send you my phone number.
(berskine@mail.com)

Also I noticed you were using a Beatie screen w/ grid markings. I take it that they have no effect on the image once the GG is in motion. The second issue that is surprising to me is your using a focusing screen with the fresnel and GG as one piece. I tried this and encounted a problem and wondered if you have yet to test it and if so how you got over the following issue:

As we all know fresnels exist on one side of focusing screens because it helps reduce the issue of having a hot spot in the middle. It does this by bending/colminating the light to a point - the point where your eye, or in this case CCD is located. Sounds good but put that same focusing screen in a oscillating motion and you move more than the GG. You move the fresnel around right there with it. This causes a problem because that point the fresnel is focusing the light is shifing all over the place - moving to and away from its intended target (the CCD sensor) because the focusing screen and CCD are moving independant of each other. The effect is you begin to see the problem of light fall off show up again. If you turn it very slowly you will see one edge of the frame bright and clear while the other side the light is falling off. Now put it in fast motion and it appears as if only the center of the frame is bright. I hope that makes sense.

So Dino did you see this effect too? If so what are you doing to get around it? Personally I'm fixing the problem by making the GG and the fresnel seperate pieces so that the fresnel is static and always in line with the CCD while only the GG moves. Then I took the idea one step further. I knew that frenels dont produce images that are as optically clear as a traditional lens so I plan on replacing it with one or possibly two field lenses (PCX).

Thats where Im at right now. I'm working with a camera optical engineer to help me find the proper field lens(es) to take over the job of the fresnel lens to produce the ultimate in picture quality.

P.S. Let me know if your interested in a source for custom calibrated medium format screens without gride lines.
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Old October 24th, 2004, 05:11 PM   #251
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dear Bret..correct me if im wrong but the "beatie screen w/ grids..custom mills etc.".. you were refering to me? (dogus not dino?)

bret i would be happy to send you prices and the mills..please drop me a mail at dosealas at tumgorsel dot com.. the beatie screen with grids of course has effect on the final result...i used that screen for testing purposes only..as i found there is a great difference in image quality between the medium and high format..i have made a great research on fresnel lenses..and i have come to this conclusion...when light hits the gg the image is diffused to every direction..light passes through the slr lens and on to the gg...the light enterinng the slr lens comes from all directions also but the light amount that passes paralel to the lens is much more than light rays that go through the lens non-paralel..since thouse non-paralel rays hit the inside on the slr more and dont find their way out..this results as the image being brighter in the middle and dark on the outside .. the fresnel lens has the property of changing the direction of light rays (paralel and non-paralel) to the paralel path...so theoreticaly there should not be any heterogenese light..but this is theoretical and has not been tested yet.. i hope to be testing in this week..(i have final exams in a few weeks and i dont know if i will find the time)..but i have tested on other gg's for i am ready for such a fault in the fresnel lenses..but i must admit the fresnel gg has very low light loss..which is really amazing when compared to ordinary gg..in my experience plastic and glass too differ..the few plastics i have tested all had very low light transmition compared with glass..and even 4mm glass compared to 1.5 mm glass gives a great difference in f-stop values..i think if the beaties screens give results as you mentioned...the step i will take to get over this issue will be your way.

bret what was the gg with fresnel you used?yes i am still studing on this project and i would love to read more about the custom calibrated medium formats.

les can you also send me a link of your work and images..

dino i have not considered any kind of motor yet..i want to first assemble the parts and then see how much power is needed..i have talked with a remote control helicopter freek who makes his own helicopters..we have gone together through the subject and we have left enough space covering a wide range of motors in the design..
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Old October 24th, 2004, 10:19 PM   #252
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Dogus-
Yeah sorry I was thinking Dogus and typed Dino. As far as the issue with the fresnel lens. Its pretty easy to see the problem. Simply hold the screen in front of the lens your planing on using and move it around a few mm by hand. You'll see it.

The calibrated focusing screens I was talking about are the Maxwell screens. They come in all sizes and focal lengths. The fresnel is made up of tighter/sharper groves then even the Beatie screen. They are reguarded by many medium format photographers as the best out there yet many dont know about them because I believe you can only get them thru Maxwell Precision Optics. Keep in mind though that these are one piece fresnel/gg screens so unless you find some way to get over the issue above they will be useless. However they will work great for the people designing static mini35 adapters.

Anyways the email is on the way.
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Old October 25th, 2004, 06:06 AM   #253
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eccentric shaft

hi Dogus do you think your machinist. could make a smaller version of the eccentric shaft . 5mm or 6mm ?
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Old October 25th, 2004, 10:59 AM   #254
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yes i suppose he can make them aswell as long as you send a detailed plan of the mills you want..
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Old October 26th, 2004, 10:22 AM   #255
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eccentric shaft with parts list

thank you dogus. the plan is to use this parts list

1http://www.thorlabs.com/ProductDetai...oduct_ID=11138

2http://www.vxb.com/miva/merchant.mv?...egory_Code=6mm

3 this will be a link to a 6mm eccentric shaft

4http://www.thorlabs.com/ProductDetai...roduct_ID=1018

5 http://www.thorlabs.com/ProductDetai...oduct_ID=36109

6 http://www.thorlabs.com/ProductDetai...roduct_ID=1480




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