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Old April 20th, 2005, 11:48 AM   #16
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To answer your implicit question, David: it's true, some interchangeable lenses for DV cams are manual focus.

We're all keeping our eyes on the NAB posts, esp. in this HD100 forum, to learn about the lens options. So far, two zooms have been demoed at the convention for this cam; if I recall right, both are manual focus.

That's not to say JVC won't market an AF lens for the HD100, nor that some other maker's AF lens won't be adaptable. But nobody really knows yet.
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Old April 20th, 2005, 12:43 PM   #17
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I also have been shooting broadcast cameras for many years - decades, even. I have worked with Canon, Fujinon, Angenieux lenses...I have never come across an auto-focus broadcast-style lens. I've never worked with autofocus until I played with consumer cameras. Personally, I hate the feature and turn it off whenever I have to use a consumer cam.

I guess that is why I do not understand why some are wondering about this feature. I find it intrusive and unnecessary. I understand run-and-gun shooting. I was a TV photojournalist for 10 years. I've also shot many sports and documentary programs. I did a lot of focusing on the go. You did it by either focusing to infinity (if the scene were far enough away) or used a best-guess and focused by the numbers scale on the lens. Now, with HD the focus will be more critical. Still, I prefer to go by my instincts and/or the numbers scale on a good lens. I prefer to have full control of the lens, be it focus, iris or zoom. I always shoot in manual iris -always. This is why I prefer the JVC to the Panasonic and Sony. It has features a broadcast veteran would love. It seems so much more like a "real" camera to me.

This, by the way, has nothing to do with the original post about underwater housings. I have very limited knowledge on that subject. I can see where focusing could be a problem, though.
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Old April 20th, 2005, 12:48 PM   #18
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Thank you, Glen, well put.
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Old April 20th, 2005, 12:59 PM   #19
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This is just my guess, but I'm 99.9% certain this camera WILL NOT have auto focus. The camera uses standard broadcast style lenses, 99% of which are manual focus only. The remaining 1% are specialty lenses such as this one by Fujinon:

http://www.fujinon.co.jp/en/news/n_040419_2.htm

Prosumer DV cameras like the XL1 and XL2 achieve autofocus by TTL-video signal detection within the camera head. So AF sensor and circuitry is within the camera, not the lens. But broadcast cameras do not have any autofocus system built inside them. This JVC is the same way.

Further evidence is the system chart for the HD100, which only list standard manual focus broadcast lenses:

http://www.jvc-victor.co.jp/english/...hd100/sys.html
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Old April 20th, 2005, 01:03 PM   #20
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FYI, it has been confirmed, no auto-focus.

There is a direct quote from JVC's new HD100 web page that describes the "Full Auto" button. It basically says it is auto for everything except focus. Guess that answers that question.

I agree, it isn't needed for anyone used to shooting with a pro broadcast shoulder-mount cam.

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Old April 20th, 2005, 01:36 PM   #21
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On some cameras I have used, when filming concerts from a distance, connected to the sound board in the middle of the hall, and I zoom out and back in, I often find I lose the focus when in manual, so I use the AF and the auto focus quickly adjusts itself. Maybe I was doing something wrong, not sure it that's supposed to happen. To me, having to deal with keeping iris at a good level for the changing stage light, and the camera steady on an ever moving lead singer, guitarist, etc, and controlling the zoom, I normally would leave the focus on auto. But I am confused as to why zooming, the camera would lose its focus in manual mode. Any explanation for this? Is that supposed to happen. BTW, none of my cameras used interchangeable lenses, often a vx2000 was used. Would losing focus be a problem with zooming on a system like the HD100?
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Old April 20th, 2005, 01:45 PM   #22
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Well, I guess there are two possible options for that.

The obvious one is that you've knocked the focus ring as you zoom (assuming you're using the zoom ring rather than the rocker) - but I'd guess you've thought of that!

The more likely option is that you're setting focus on the wrong end of the zoom - were you zooming in to the tightest you could and then setting focus, or setting focus at a wide setting and then zooming in?

The correct way to set focus is to zoom right in tight and then focus before zooming back out to the shot you want. This should guarantee perfect focus. Also, this method means that focus is set well for the shortest DOF you will be getting - as the lens's focal length becomes shorter (when you widen the shot) the DOF will *increase*, assuring you a focus that is still spot on. If you approach the problem the other way, not only is it hard to set accurate focus as the subject (and detail thereof) will be very small in frame, but as you zoom in you shorten your DOF and the subject may then drift out of acceptable focus...

Other than that, I can't think how/why you should have any problems, unless the subject is moving radically nearer or farther from your camera - in which case they may just have stepped out of the split.
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Old April 20th, 2005, 01:47 PM   #23
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I've done live concert stuff for jumbo vision with a betacam and never had problems with focus.

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Old April 20th, 2005, 02:35 PM   #24
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That's the difference between pro cameras (betacam-type) and prosumer (i.e. VX2000, XL-1, etc.). In other words, if there is a REAL lens and if its backfocus is set properly, you won't have problems loosing focus when zooming back and forth. That's why it is so exciting to get a real lens on a $6k camera.
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Old April 20th, 2005, 09:34 PM   #25
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Quote:
Originally Posted by David Gomez
On some cameras I have used, when filming concerts from a distance, connected to the sound board in the middle of the hall, and I zoom out and back in, I often find I lose the focus when in manual, so I use the AF and the auto focus quickly adjusts itself. Maybe I was doing something wrong, not sure it that's supposed to happen.
But I am confused as to why zooming, the camera would lose its focus in manual mode. Any explanation for this? Is that supposed to happen. BTW, none of my cameras used interchangeable lenses, often a vx2000 was used. Would losing focus be a problem with zooming on a system like the HD100?
In a broadcast camera, that sounds like a back-focus problem. This is easily corrected in the field (yet another reason to choose the JVC HD100), but I do not know how to correct such a condition in a non-interchangable lens.
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Old April 20th, 2005, 09:42 PM   #26
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Prosumer cameras have auto-focus because they have to...

Pro Broadcast cameras have high resolution viewfinders that make it easy to achieve focus. Also most prosumer cameras have no focus markings for one to guide himself by.

If this camera doesn't have an excellent viewfinder and markings, no auto-focus might turn out to be a real pain.
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Old April 20th, 2005, 10:05 PM   #27
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If this camera doesn't have an excellent viewfinder and markings, no auto-focus might turn out to be a real pain.[/QUOTE]

This camera (the HD100) does have an excellent viewfinder - 2, actually - and true focus markings. In my humble opinion, no auto focus is necessary. If it did have auto focus, I'd turn the damn thing off.
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Old April 20th, 2005, 10:23 PM   #28
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Focus is a breeze on the HD100 because of the viewfinder peaking. The "focus assist" function is yet another type of peaking, just on steroids.

If you don't know what I'm talking about quite yet, trust me. Few will want autofocus after learning how easy critical focus is on a display with peaking.
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Old April 25th, 2005, 08:02 PM   #29
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35mm lens autofocus

many SLR 35mm lenses are autofocus right? when someone releases a 35mm lens adaptor for say canon SLR lenses will that autofocus be any use? (sorry if that's a dumb question)
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Old April 25th, 2005, 08:14 PM   #30
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Quote:
Originally Posted by Nate Weaver
Few will want autofocus after learning how easy critical focus is on a display with peaking.
Especially when peaking is implemented as well as it is on the HD100. You've got an analog dial that lets you choose from "mild" to "wild". Very nice.
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