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Bayonet mount Lens questions


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#1 Nick Harris

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Posted 16 April 2008 - 06:32 PM

I'm in the market for the HPX500 for use in narrative shooting situations. I've got the budget to go with some nice lens choices which I feel is the real investment here, as I am looking for lenses that will do me well through an upgrade in camera body down the line.

I'm somewhat stuck in the mud as far as where to even start looking for reasonably priced lenses.

Do I need to exchange the bayonet mount for digiprimes? What sort of lenses aside from the normal ENG style zooms will mount on the camera as it comes from Panasonic?

Do the digital cinezooms offer enough DOF or would I do best to stick with digiprimes?

I got all excited when reading about Canon's new AVC-235 anamorphic lens converter, but then saw that it retailed for what would be an additional $25,000 that I would prefer not to spend just yet (however I wouldn't mind making lens choices in anticipation of a later purchase of the AVC-235).

However, I did start looking at Canon's FJ digiprime series, which is also a bit pricey.

So I'm thinking a pair of digital cinestyle zooms might do the trick at least for the moment. Will these lenses give me adequate shallow DOF, or will they still look deep and video-ish?

Any suggestions as for places to look for digiprime sets that might be a little more affordable?

Any advice would be much appreciated!
-Nick Harris
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#2 Michael Nash

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Posted 16 April 2008 - 06:45 PM

The HPX500 uses the B4 mount that's standard on all 2/3" 3 chip cameras. All the lenses you mentioned share the same mount. Forget the term "bayonet," as that refers to the way the mount works, not a particular mount or size. There are many different bayonet mounts.

The depth of field is the same between all those lenses too, since the chip size isn't changing. There will be a qualitative difference between zooms and primes, but optically it's all the same depth of field characteristics. 2/3" chip cameras use essentially the same focal lengths as Super 16. For many productions that's shallow enough, for others 35mm optical characterisitcs are preferred. If you're upgrading from shooting with 1/3" chip cameras you'll notice a pleasant improvement with 2/3" optics.

You can look up depth of field charts here.
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#3 Chris Keth

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Posted 16 April 2008 - 10:47 PM

Michael is right on all fronts. I have one thing to add. When/if you measure for focus, the type of lens on a B4 mount camera will make a difference in how you measure. Cine style lenses are made with scales that have you measure focus to the sensor plane. ENG style lenses will have you measure from the front element of the lens. I don't know why there is a difference, but there it is.
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#4 John Sprung

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Posted 17 April 2008 - 07:26 PM

The HPX500 uses the B4 mount that's standard on all 2/3" 3 chip cameras.

I've been looking at the specs in the manuals on the manufacturer's web sites, and found something a little odd. Sony and Thomson use the term B4 mount, while Panasonic and JVC say either 2/3" Bayonet or 1/3" Bayonet. Is there some slight difference between the mounts, or is the term B4 a trademark or something? Are there really different mounts for 1/3" and 1/2"?




-- J.S.
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#5 Michael Nash

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Posted 17 April 2008 - 07:46 PM

I'm not sure about trademarks, but as I understand it Sony's 2/3" "bayonet" mount is called B4. 1/2" and 1/3" video camera mounts are definitely a different size than the 2/3" mount, and they're sometimes called "bayonet" also. Not all 2/3", 1/2", or 1/3" mounts are the same either. I think Sony calls their 1/3" mount B3.

Arri also uses the term "bayonet" to distinguish from "standard," hence the confusion when that's the only term used.
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#6 Nick Harris

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Posted 03 June 2008 - 08:04 PM

Thank you guys so much for responding to my questions. I ended up buying a Fujinon HAc15x7.3 cine zoom and I'm INCREDIBLY pleased with the look and performance of the lens. With that puppy riding upu front this camera is quite the head turner.

If you're interested in seeing some stills and a compressed video I cut from my test shooting mosey on over to my website, http://harrisfilms.com

-Nick
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#7 Riki B

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Posted 16 February 2013 - 12:59 AM

The HPX500 uses the B4 mount that's standard on all 2/3" 3 chip cameras. All the lenses you mentioned share the same mount. Forget the term "bayonet," as that refers to the way the mount works, not a particular mount or size. There are many different bayonet mounts.

The depth of field is the same between all those lenses too, since the chip size isn't changing. There will be a qualitative difference between zooms and primes, but optically it's all the same depth of field characteristics. 2/3" chip cameras use essentially the same focal lengths as Super 16. For many productions that's shallow enough, for others 35mm optical characteristics (spelling corrected by RSB)  are preferred. If you're upgrading from shooting with 1/3" chip cameras you'll notice a pleasant improvement with 2/3" optics.

You can look up depth of field charts here.

For what it's worth in the history of television and of various parts and so forth the B-4 mounting specifications were drawn up by NHK (Nippon Hōsō Kyōkai or Japan Broadcasting Corporation) and not by Sony. As such the B-4 mount did become a standard among lens manufactures.  The reverse capture of the B-4 was standardized upon by Ikegami (ring on the lens barrel versus camera body) and as we all know they are not cross compatible... Sony won. Specifically Ikegami came out with a camera (The EC-35) for video-cinematography in 1983 long before such things were really though of seriously. Though it did win an Emmy for technical achievement most agree that its "market" failure was the lack of the ability to mount Arriflex or Panavision lenses which generally turned off those who could afford to use it.  


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