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Old April 23rd, 2008, 07:04 PM   #1
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JVC HDxxx/Sony Z7 native 35mm idea

Not sure if this is the right place to post this, but if not please move it, however this pertains to the straight Nikon to JVC mounts which are more prevalent in this forum than the Alternative Imaging Methods forum.

Anyway, here's the idea. Okay, we all know that the straight Nikon to JVC adapters give a 7x magnification and are more useful for really long shots or wildlife stuff. With a 35mm adapter, you get the option of using practically any lenses you want with the added benefit of shallow DOF. For the 35mm adapter to work, you've got to zoom in through an achromat to focus on the ground glass within the adapter and record the reflected image coming from whatever lens you're using.

Okay, now what about using a really wide lens, like 18mm to 20mm, and connect it to the camera natively, then take the achromat out of the equation, and simply use the Nikon lens as a sort of relay lens?

Now, I don't know if the achromat will be necessary or if you'll have to use spacer tubes in addition to or instead of the achromat. But if the lens isn't too far telephoto, perhaps it could be the perfect solution to having to use the long stock video lens. It would go: Good glass ---> Adapter ---> Good Glass!

Again, I don't know if this would work or not but I'm just throwing it out there just on the outside chance that this will in fact work.
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Old April 23rd, 2008, 08:15 PM   #2
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Your on to something, but wide nikon lenses are really slow (for a 1/3" camera) and heavy, not to mention bulky. They will also cause the ground glass to vinnette unless condensing elements are used. What you need is like an f1.4 max aperture relay, that is short, lightweight, & sharp. I have been working on one for sometime. I will keep you updated when its finished (Parts are in line to be milled right now)
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Old April 23rd, 2008, 08:15 PM   #3
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http://www.dvinfo.net/conf/showthread.php?t=118228

Someone already did it.
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Old April 23rd, 2008, 11:17 PM   #4
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I'm Sorry but that footage shows severe vinetting.
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Old April 24th, 2008, 12:19 AM   #5
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I'm Sorry but that footage shows severe vinetting.
it also looks very very soft, at that size even compressed, it should still be much sharper than that.

I really don't think theres a way to around using an actual relay lens... Its all just a cheap work around that defeats the purpose of using nice expensive glass.
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Old April 24th, 2008, 01:20 AM   #6
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Hmmm, perhaps if a 24mm F2.0 had been used, the light loss wouldn't be as great. As far as it being magnified, that's why I suggested the 18mm or 20mm with, perhaps, the use of spacer tubes so you're not filming entirely in telephoto. Remember, softness could be caused by several factors.

Another option I found was a Tokina 11-16mm zoom. Now, the only worry I have with it is slight distortion, but then you've also got to consider the magnification factor on the center of the lens, thus maybe not as much distortion. Having a wider lens should help to some degree as far as I undestand it, the lens also being a DX lens may or may not affect the image as well but it just depends. Not owning either camera, adapters, or lenses for this test is kind of a hassle. ;)

(I'm stuck in a waiting game. Thanks a lot grad school!)
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Old April 24th, 2008, 02:25 AM   #7
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The problem with using 35mm lenses to project onto a 1/3" sensor (optically speaking) is that 35mm lenses were made to project to a 35mm sensor, a broadcast quality 1/3" HD lens has more resolution than a 35mm lens when projecting an image onto such a small plane. There will be significant image softness unless you are using the best 35mm glass there is and stopped down to f5.6. Having owned the nikon 24mm f2 I can also tell you its not the sharpest lens when wide open.

Again like I said though, I am working on a compact, fast, sharp, and affordable custom relay system compatable with most 35mm adapters. (I am using the sgpro as a preferred set-up) In the next 8 weeks I should have something ready to show.
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Old April 27th, 2008, 12:51 AM   #8
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Quote:
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I'm Sorry but that footage shows severe vinetting.

Quote:
Originally Posted by Giuseppe Pugliese View Post
it also looks very very soft, at that size even compressed, it should still be much sharper than that.
say what? I always say..whatever tickles your pickle...If you like super ugly and super sharp images with everything in focus...go ahead...knock yourself out with the stock lens....but then that is my opinion and what does it matter...

My setup puts out an incredible image...may not work for everyone, but for the creative work I use...It works fantastic...lighting situation and user error contributed to whatever you guys are seeing as maybe a "flawed" image...but then again I showed the video to a couple of PS Technik guys at NAB and they liked it...but then again they are engineers...what do they know about anything....

and by the way...I am not taking it personally
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Old April 27th, 2008, 10:57 AM   #9
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not taking it personally eh? I just noticed that the left side of that footage looks dark (some shots worse than others). I love the little munchkins though!
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Old April 27th, 2008, 12:08 PM   #10
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not taking it personally eh? I just noticed that the left side of that footage looks dark (some shots worse than others). I love the little munchkins though!
yeah I had to put that comment up before anyone accuses me of sour grapes...I do realize though that some of the footage has a vignetting in the left side but that cold be attributed to several factors....first...first day I had that contraptions and I was pretty much holding it by hand...second....maybe lens? I have changed the set up since then....

darn you guys..now I have to post new footage with the new lens....

now i would take it personally if someone dissed my girls :)

I do value these comments as I am trying to make the ultimate adapter for my own use and then share the wealth......
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Old April 27th, 2008, 12:20 PM   #11
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you guys are also forgetting that with a 3CCD image block, the R, G, and B don't come to focus in the same plane. if 1/3 CCD blocks did away with this because its a new standard, that would be welcome, but 1/2 and 2/3 cameras do have this issue because people wanted to slap tube camera glass onto their then new CCD cameras back in the late 80's. with tube cameras you could adjust the focal plane point of each tube, so lens makers made some compromises in lens design to create those early zoom lenses longer and wider knowing that they didn't have to get RGB to focus exactly the same plane. too bad the camera manufacturers didn't say no back when the came out with the first 3CCD cameras... so AFAIK, its its the same for 1/3 blocks.

I'll also agree that the line/mm for a 1/3 lens needs to be MUCH higher then a 35mm frame. having put some 35mm glass onto the HD100, its been softer then the stock lens. so any custom relay lens would need to take into account the RGB focal plane differences, and ideally be a super fast F1 or 1.2 lens.
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Old April 27th, 2008, 03:11 PM   #12
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For reasons I don't completely understand: 3-chip prism blocks are limited to an f1.4 maximum aperture. You cant effectively use a lens with a maximum aperture larger than than f1.4 due to prism design specs.
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Old April 28th, 2008, 10:08 AM   #13
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thats the transmission value of the prism. basically the light is split 3 ways, therefore each chip gets 1/3 the light entering. it has nothing to do with the lens iris.
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Old April 28th, 2008, 02:42 PM   #14
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Why would a light transmission value be rated as an F-stop? I still dont understand, but I know there must be a good reason that there isnt a single lens made for 1/3"-2/3" 3-chip that has a maximum aperture greater than f1.4. If using a lens with a maximum aperture of more than f1.4 on a 3-chip camera were plausible, we would have seen it on the Dprimes.
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Old April 28th, 2008, 03:13 PM   #15
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Why would a light transmission value be rated as an F-stop?
why shouldn't it ? its much easier math in figuring light loss, its a number people understand, as opposed to something like lux or lumens, or even fc of loss.

[QUOTE=Hunter Richards;868982
I still dont understand, but I know there must be a good reason that there isnt a single lens made for 1/3"-2/3" 3-chip that has a maximum aperture greater than f1.4. If using a lens with a maximum aperture of more than f1.4 on a 3-chip camera were plausible, we would have seen it on the Dprimes.[/QUOTE]

the short answer is getting to a F1 or 1.2 would require a larger front element, lens body, and iris. at some point there is diminishing returns in terms of cost / size / weight / T value ( which is the correct term, not F ). There are some superspeed primes at T1.2. if a D prime of T1.4 is $10k, would you be willing to spend $20K or more for a T1.0 ? probably not. would it be worth having the already large glass even bigger ? it would in some respects defeat the purpose since anyone using such glass is most likely also shooting low light and wanting to be mobile. take a look at still camera lenses. there are T1 and even T.9 glass ( Lecia 50mm ) but they are also very expensive.

here is a F1.2 video lens

http://www.securitybusinessworld.com/catalog.html

scroll down the page here F1.2 and F1 glass

http://www.turnkey-solutions.com.au/...ron_lenses.htm

and here, specifically stating 3CCD compatible

http://www.jknelectronics.com/cosmicar.htm
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