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Old January 30th, 2004, 02:10 PM   #106
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Just a thought. Has anyone looked into magnifying the image before it hits the ground glass? Like using a larger ground glass and magnifying the image to say three times it's normal size. This would seem to solve a couple of issues. If the ground glass image was bigger the ground glass wouldn't have to be as finely ground as Alains is. There would also be need for less powerful macro lenses on the DV camera.

I assume it wouldn't be as easy as sticking a magnifying glass between the 35mm lens and the ground glass. But why not?
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Old January 30th, 2004, 02:23 PM   #107
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Mike--

Nice thought but at what point does the projected image begin to bleed over the sides of the ground glass? For those who have a mock-up already, is there a way to tell the size of the image you are getting? And what about the fresnal solution on the Agus35?

And as far as the 72mm on the dvx100, we might have to make one adapter for dvx owners and one for everyone else . . .
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Old January 30th, 2004, 02:33 PM   #108
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Yes, the DVX-100 is a big problem. Perhaps if enough DVX owners can get together they might be enough demand to make 2 versions?
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Old January 30th, 2004, 03:14 PM   #109
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All dvx owners should also check out the advances on this project at www.dvxuser.com. Go under the "cinematography" thread followed by the "mini35" thread.

As far as magnifing the 35mm lens' image before its projected on the ground glass...I wish it worked that way but apparently doesnt. In doing so you will change you the DOF characteristic of the lens in a negative way. If one could just make it larger without a effect then a even better solution would have been just to make it smaller instead so that the image project straight on to the camera CCD instead of the ground glass (in the case of the XL1). But if that worked P+S Technik would have never gone through the trouble of using a intermediate image/ground glass system. Optically I dont know why this happens but I would love to hear from a optical designer about it.
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Old January 30th, 2004, 03:28 PM   #110
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Speaking of optical designers, I'm hoping that once we submit our spec that this chinese company will be able to provide some insight into problem solving/overcoming some of these issues. They seem to be a pretty sophisticated outfit. They may even be able to solve the orientation issue . . .
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Old January 30th, 2004, 03:35 PM   #111
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The orientation issue isn't a problem. Each lense inverts. It's just expensive. You could have an arrangement that is

35mm lense--GG----parrallelogram prism (or mirrrors arranged in the same way---Anachromatic lens----Parrallelogram prism--- camera.

I've been expermienting with this type of arrangment with mirrors on a tabletop. It works alright. It just needs someone who can make it to a high degree of competence! The camera focuses on the reflection of the GG in the last mirror in the chain.
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Old January 30th, 2004, 05:07 PM   #112
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Another thought

Related to the whole idea of these devices, is there a way of doing remote focus with modern DV cameras? I use Glidecam a lot and so the focus critical nature of such lenses would make it essential for such use.
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Old January 30th, 2004, 05:22 PM   #113
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What I meant to say was a remote focus that operates by way of a roller that adjusts the 35mm lens as opposed to the camera itself which wouldn't make any difference other than to defocus the entire picture!
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Old January 30th, 2004, 07:35 PM   #114
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Simon, I have seen one for Arri cams, so naturally it cost Thousands of dollars just cuz its Arri made.

Essentially it was a large gear affixed to the lens with a stepper motor fixed on the rods. It could be made, but not easily.

I think it was called a 'follow focus'

like this but with a motor.

http://cgi.ebay.com/ws/eBayISAPI.dll...&category=4691
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Old January 30th, 2004, 08:30 PM   #115
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Remote Focus:

http://www.unitcine.com/

cheaper than most of the bigger names I've seen. The main 'big' Hollywood remote focus systems are made by a company called Preston.

Hope this helps.
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Old January 30th, 2004, 11:35 PM   #116
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I'm still interested in what others have discovered is the most viable alternative to hand-ground glass??

This, IMO, is the biggest hurdle to leap at the moment. Rail systems can wait.

Anyone purchased materials or heard from Knight Optical? I've written them twice, but to no avail.

American companies haven't responded, either.

- jim
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Old January 31st, 2004, 12:59 AM   #117
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Well Jim, Its my take that the GG issue has been solved

Alain's homemade GG made from a UV filter would be optimal for these reasons:

Pro's
1. The glass is already optical quality
2. UV filters are cheap and readilly available
3. It only takes an hour to make
4. No glass cutting required
5. Filters are already threaded and ready for adaption

Con's
1. Aluminum Oxide grit is only available online unless you have a telescope shop around.

I just need to get off my ass and order some grit!

I found this place, it has SUB MICRON GRIT! cheap as hell too at a pound for $14.79 [AL-601]

http://www.micronmetals.com/aluminum_oxide.htm
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Old January 31st, 2004, 02:08 AM   #118
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35mm end

I personally have a Canon A-1 35mm lens...and I'm sure others have something different than an f-mount.

Would it be possible to front thread the thing with something that an adapter (either a 52mm thread to f-mount adapter, or a thread to canon fd adapter) could fit on?

Might save some of us from buying new camera lenses. (especially when we don't even own the cameras they go to)

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Old January 31st, 2004, 03:52 AM   #119
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I only suggested a Nikon F mount since it seems to be the most prevelant in the 35mm industry. It's the only mount that hasn't changed in 50 years and because of this there is a large variety of both Nikon and third party lenses made for this mount over that period of time. You can buy an old used lens or a brand new one, a cheap lens or an expensive top of the line one and they all will work.

Sure there are a lot of people that have a lot of money invested in lenses for other camera systems. Consider though that their primary reason for buying those lenses were for the still camera they go to. A camera they still have and can still use with those lenses. This video adapter would constitute "a new camera" or "new camera system" thus buying lenses for it would be a given.

If the adapter just so happened to work with lenses you already owned then great. But it should be expected that as a new camera system new camera lenses may be required.

Just as a note though, I suggested the Nikon F mount for the reasons above and not because of any bias. I actually own more Minolta MD mount lenses then Nikkors. But looking at the broad scope of it the F mount would seem to be the practical choice for the reasons stated above. Versus trying to cater to everyone and their lens mount biases. Because trying to look at it from an engineering/production point of view the simpler the product the cheaper and easier to build. In other words it's easier for everyone to fit the product then it is for the product to try and fit everyone. Sure it may not be the most desired route, but in the end it would make it cheaper for us which is the whole motive behind all these discussions and projects.

If everyone decided to go with a Canon FD mount instead I wouldn't not buy the adapter. To me it would be the same as buying an XL1 knowing full well that my Nikkors or Minolta MD lenses wouldn't work with it. That I was buying into a new camera system and would need new lenses for it. But then again I look at the notion of this factory produced video adapter not as an extra toy or extension of my existing 35mm lenses but as a new tool in itself that may require it's own set of lenses and accessories. But if it does what it's meant to do it would be worth it and still only be a fraction of the cost of a min35.
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Old January 31st, 2004, 04:09 AM   #120
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Just as an addendum

I think we're all going to have enough on our plate trying to figure out how to mount our DV cameras to such a factory adapter. Keeping the front end of it as standarized as we can would be our best route. Different 35mm lens mounts have different flange to focal plane distances. Having to deal with lens mount adapters (possibly special made ones) on top of having to deal with the DV camera alignment would be even more troublesome. If we build the front end to a specific standard (such as the F mount, or a different mount) then at least we know that part of it will work no matter what when we attach a lens made for that mount. From there the only thing we have to troubleshoot is the DV camera fixture.
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