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Old May 14th, 2009, 08:52 AM   #1
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Broadcast 2/3 Canon SD Lens or HD Pro JVC 1/3 will work?

I got my hands on some broadcast Canon lenses for TV use (2/3) and I was wondering if they'll work on my JVC HM700 buying a specific adapter (ACM-17 from Fujinon or JVC). Obviously I'll lose wide angle but tele seems to be very good! The lenses are for SD use but broacast. Will they have the definition I need in HD ? Is it worth spending 700$ for the adapter? Do they exist any similar (and cheaper) adapters by other brands ?
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Old May 14th, 2009, 01:19 PM   #2
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Mike Tapa has just announced a 2/3 to 1/3 mount that may be of interest:
MTF Services Ltd
A lot cheaper too.
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Old May 14th, 2009, 03:46 PM   #3
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Quote:
Originally Posted by Marcello Mazzilli View Post
Will they have the definition I need in HD ?
Unlikely, even an HD 2/3" lens theoretically won't look that good on a 1/3" chip camera as it's not designed to resolve such small pixels. So an SD lens will be even worse.
Not speaking from personal experience here, just optical theory, but be careful.
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Old May 15th, 2009, 10:03 AM   #4
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Thanks Steve. Gary's prices seem quite interesting.. and even if Steve is right I risk only 150$ to get the BC Lens to work.. But.. Gary... which is the model I should buy... ? I don't see any 2/3 to 1/3 adaptor.
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Old May 15th, 2009, 11:25 AM   #5
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Its the B4 to 1/3" adaptor you need
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Old May 15th, 2009, 03:01 PM   #6
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Marcello

The device Gary is referring to is here.

B4 to 1/3" bayonet adaptor
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Old May 16th, 2009, 02:42 AM   #7
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Thank you very much to both! I think I'll get it and see what happens
M


Just bought it.... I'll let you know... I expect little CA, x1.8 magnification (no wide angle, huge tele) and maybe just a lack of definition...
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Old May 16th, 2009, 05:53 AM   #8
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Hey Mike.. I didn't relise it was yourself selling the adapter ring!
Cool ;)
I'll let people here know how it goes. Do you think the camere itself will have problems with the extra weight in the front... Is the original JVC camera ring strong enough to hold the extra ring and bigger lenses? Also I'm quite curios to see if SD Broadcast lenses can substitute (not for wide angle) HD Pro-sumer lenses (obviously not for wid angle!) . Definition is the issue here.
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Old May 27th, 2009, 03:57 AM   #9
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Hi Mike.. I got the adaptor and works fine. The broadcast lens works fine. I get an incredible tele (more than 3 times zoom with the 2x doubler on). I get some CA that looks too much similar to the one I get with the standard 16x lenses.... this "pixel shifting issue" starts to worry me. But anyway.. now I have a solution for long distance shots like nature shots or events (the podium). I loose wideangle obviously so I cannot use this lens as a standard lens. Finally.. I have no means to do a serious quality test to see if I keep all the line definition but by the eye seems fine.
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Old May 28th, 2009, 05:20 AM   #10
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Marcello.

I'm glad that the adaptor is working well for you.

Let us know if you ever put any clips up online somewhere.

Cheers
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Old May 30th, 2009, 11:03 AM   #11
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Marcello,
There was definition chart posted online here somewhere that you can print out and get a good idea of sharpness with different lenses. I'll try to find it later and update my post.

Please stop referring to the CA as a "pixel-shifting" issue! That's a misnomer, and I think you've had some clear explanations with direct evidence from reliable sources.

If in doubt, look at the very extensive CA discussions on the JVC GY-HD series forum. CA was a constant issue of discussion with these cameras (especially with the same 16x lens you have, inherited from that series).
The GY-HD series does absolutely no pixel-shifting, and is just as subject to the problem.

In fact, for further convincing, when you have a situation exhibiting CA, turn off the pixel shifting by going into 720p mode. You'll find no advantage!

BTW the optical physics of resolution from using a broadcast SD lens for a larger chip camera on a smaller chip camera is up for discussion. There are factors that can be theoretically argued for both better or lesser resolution than a standard lens.

The consensus I've picked up from people actually doing it, is that results are very good if the lens you are adapting is considered a quality lens.

PS - I think the resolution chart and some of this discussion came from the EX3 section of dvinfo.
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Old May 31st, 2009, 12:05 PM   #12
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Ok ok.. I'm convinced about the piel shifting.. Is just that I never had this problem before with pro-sumer cameras like PD150 and Z1 and it was not a nice news for me. Also my reseller sent my complaints to JVC Italy that said..... "Yes we know, that is, can't to much about it". Anyway.. let's see what comes with the new 17x (when I'll put my hands on them).
Thanks for the resolution chart offer. Yes.. I'll give it a try (you have to give me some instructions... do I have to stay full wide, full tele or half way through? How do I "read" the chart. Etc... I'm going to shoot some nature footage nex week on some wonderfull islands south of Italy. I'll bring Canon 2/3 lenses with me and see what happens. one thing.. It seem I cn't get a proper back focus with this 2/3 lens.. probably because the distanc from the CCD is not exactly the one supposed to be... so I can get it in focus but I have to check every time.. either is on focus full tele or full wide, but not both at the same time.
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Old June 2nd, 2009, 06:14 AM   #13
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Marcello.

To set back focus:

Zoom to the tele end and focus on a far object in the normal way.

Zoom back to the wide end, now adjust the back focus to get the same object in focus.

Then repeat the process 2 or 3 times always remembering to adjust lens focus for the tele end and the back focus at the wide end.

You may well already know this procedure, but its surprising how many people don't.

I hope this helps.
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Old June 5th, 2009, 06:04 AM   #14
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sure I know the procedure... but it doesn't seem to work with this 2/3 lens and your adaptor.. Either I am able to get tele in focus or wide.... very strange I know but that is what happens
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Old June 12th, 2009, 12:27 PM   #15
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you probably know this too, but check that the macro isn't engaged on the lens...

Also it will be faster getting into place if you start the procedure Mike mentions above from a roughed in back focus setting instead of something really out.

You can do this with the distance readings on the lens - or have the lens focus at infinity and the back-focus producing sharp to start.
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