Curious about lenses

M

Mac

Well-known member
I, too, am considering the JVC, mainly for ergonomic reasons. I currently have an XL2 with the manual lens, (I recently sold my DVX, which had a nice lens, though not long enough).

I shoot mostly in super16, and so own an Aaton (with the Aaton mount) for which I have 5 zoom lenses - one, a Cooke, which is superb. I also have an old DSR-300 with a pretty darn good Canon lens... Okay, I own a lot of lenses..

Barry mentioned several threads ago that the supplied JVC lens is garbage but work is being considered on adapters.

How serious is this possibility and who can I talk to? (I could have Century convert one or more of my super16 lenses to fit whatever adapter becomes available). I, of course, am not interested in "C" mount, that would be way too retro...

Also, is the JVC a proprietory lens mount, or will the Canon lens from my DSR-300 fit or be converted? I haven't been able to find this info anywhere... I know for sure that the XL2 lens isn't going to work, because it doesn't have a manual iris. Thanx in advance..
 
Mac,

I too have an XL2 and DVX, and now the JVC. I can tell you that the bayonet mount on the JVC is very different from the Canon XL mount.
I also own some old 16mm C-mount lenses. On my XL2, I drilled a 1 inch hole in the centre of the body cap, created a locking "notch," and mounted my Switar 25mm ƒ1.4 C-mount lens in it. Since the Flange Focal Lengths are so different (C-mount is 17.5mm and XL2 is at least double that) the lens suddenly became and amazing close focus macro!

Why would I do such a thing to my body cap you ask? Because I'm trying to build my own version of a mini35 and I think a C-mount lens might be the ideal, close focus, short relay lens. The 25mm doesn't have enough FOV to capture the full 1.85 image on a ground glass at its MOD, so I've ordered a 12.5mm C-mount to give that a try.

To give you an idea of the FOV of the 25mm C-mount mounted on the XL2, I put a penny (Canadian) about 2 inches away from the end of the lens and the letters "ELI" (from "Elizabeth II") filled the 16x9 screen. I need to be twice as wide as that so I can focus on a 21mm x 12mm ground glass area (1:85 flat on 35mm motion film.)

I started this project before I received my JVC HD100 last week. However, two days ago I gave the JVC bayonet body cap, and a c-mount lens to a machinist friend, and he is creating a JVC 1/3" bayonet mount to C-mount adapter for me.

The bayonet mount of the JVC is very simple. It is flat, about 45mm in diameter, with three 12mm long lips protruding about 2mm. (My rough measurements.) There is also a small tit for alignment, but I won't need this for my mount.

Ok, so for the lens mathemeticians out there, the actual size of a 1/3" CCD is 4.8mmx3.6mm. The Flange Focal Length (in air) according to the lens instruction manual of the JVC HD100 is 31mm. (I wish someone knew the FFL of Canon XL mount!) The flange focal length of C-mount 1" format is 17.5mm.
What will be my MOD and FOV with a 12.5mm ƒ1.4 C-mount lens mounted on the HD100?

Will Hunting out there anywhere?
 
Mac said:
How serious is this possibility and who can I talk to?
Click to expand...
The possibility is dead serious, and probably very easy to do. All we have to do is get a camera to Les Bosher in Wales, UK. He builds camera mounts for various cameras and lenses, and his craftsmanship is absolutely superb, I've had him do work before.

If one of our UK brethren would find a way to get a camera to him for measurement purposes, he could tell us right away what mounts he could make/support.
 
That's good to hear, and thanks for the response. I will definitly consider a body only purchase. If "one of our UK brethern" makes that happen we will all be very happy.. I mean what's the point of considering HDV if the lens doesn't hold up to the camera's inherent resolution?

I would assume the likely mounts would be, as you stated before, PL and Arri (bayonet I assume). Unfortunately Aaton mount is almost as extinct as CA-1, but it is a solid piece. Do you think the standard ENG 1/3" video lens (i.e. Sony) could be converted? Back focus issues do you think?
 
Thanx Barry, I will contact him... Also dashwood, thanx for your comments. However, I am a documantary filmmaker and work mostly fast and handheld, so the option of an intricate lens system won't work for me.. That's why I like the XL2 design and am considering the JVC as my next hardware purchase.. If I can glue my Cooke and my Century/Fujinon super16 lenses onto the front of it I will be a happy camera owner - for maybe almost a whole year (funny thing is, I've owned my Aaton LTR since 1982 at it still takes state-of-the-art pictures)
 
Mac said:
I am a documantary filmmaker and work mostly fast and handheld, so the option of an intricate lens system won't work for me.. That's why I like the XL2 design and am considering the JVC as my next hardware purchase.. If I can glue my Cooke and my Century/Fujinon super16 lenses onto the front of it I will be a happy camera owner - for maybe almost a whole year (funny thing is, I've owned my Aaton LTR since 1982 at it still takes state-of-the-art pictures)
Click to expand...

You may want to wait for the GY-HD7000U for adapting your favourite S-16 lenses because it is 2/3" CCD, which will have much less of a crop factor than the 1/3" CCD in the HD100. Unfortunately, the body only will be about $28000 US.

http://pro.jvc.com/prof/Attributes/features.jsp?model_id=MDL101476&feature_id=01

If you can manufacture an adapter for the HD100 and your S-16 lenses, and match the Flange Focal length, there will probably be a crop factor of about 38% (2.3x?) Meaning a 12~120 zoom will be more like a 28~280, in S-16 terms.

You'll have to double check my math.

S-16 frame = 12.52mmx7.41mm @ 1:1.66 area
35mm frame = 20.96mmx11.33mm @ 1:1.85 area
1/3" CCD = 4.8mm x 3.6mm @ 1:1.33 ratio (XL2 crops for 16x9 - not sure what is in HD100)
2/3" CCD = 8.8mm x 6.6mm @ 1:1.33 ratio (not sure if 16x9 native chips are wider or shorter?)

Tim
 
Your math is correct, and is a major concern. That's why I'm hoping there might be a way to convert the 1/3" Canon lens (Sony mount).. I shot several docs for PBS with that lens on the DSR-300 and was very happy with the look of it (I apparently have a good one). In fact, I haven't sold my DSR for that reason, I want to hang on to the lens.. That lens, with the ability to use my 11.5-218 Century Fujinon would cover any range I'd ever need. And I'd have the bonus of being able to use my Cooke 10.5-52 for production work (an exceptional zoom lens, probably the best ever)... And I really don't want to spend over 20k for a format that could conceivably be obsolete before I finish my next film...
 
I was just thinking about your DSR-300. Isn't it a 1/2" CCD? If so, the 1/3" to 1/2" bayonet mount adapter that JVC has made for the HD-100 may be all you need to use your Canon lens.
You should call your local dealer and try it out. You will still have the crop factor, but you could try it out in the store.

Keep in mind that the resultant resolution of your Canon lens may not be sharp enough to resolve the full HD resolution on the HD100. You should compare the stock lens with your Canon + 1/2" adapter and see what happens. Maybe it will be better!
 
Good point and good advice.. My DSR-300 is a 1/3" however, the 500 is 1/2", so I'm still keeping my fingers crossed - really didn't like the chromatic abberation issues that Barry described in his comments. Lack of resolution I can live with, I always use 1/2 and 1/4 ProMists and SoftFX filters on film anyway. It's the lens' ability to focus colors on the same plane that really concerns me... To tell the truth, I haven't been unhappy with the stuff from the XL2 on my 42" palsma screen.. just jumping on yet another bandwagon I guess... Hell, it's only money...
 
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