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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old July 29th, 2006, 10:06 AM   #1
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iris control ring

The new canons have the iris control ring , so here me question

what are the uses for an iris control ring as compaired to the typical way a camcorder deals with the iris?
why would i want an iris contorl ring?
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Old July 29th, 2006, 10:36 AM   #2
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The typical consumer camcorder will have iris control via a thumbwheel, menu selection, or toggle switch.

All high end professional type cameras will use a lens with a mechanical iris ring.

Now as to the why you would want this, it's because the ring is a continuously variable iris and if you are running the camera in manual, there would be no obvious 'stepping' of the iris like you get when toggling or selecting via menu.

In other words, the iris can be slowly and smoothly rotated to bring exposure to optimum without being that noticable.

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Old July 29th, 2006, 10:45 AM   #3
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Also, every thumbwheel I have ever used was in an awkward location. An iris ring on the lens is a more approriate location which is also more ergonomic. Just like the f-stop ring on the old 35mm cameras...just where you want it to be.

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Old July 29th, 2006, 11:12 AM   #4
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An iris ring on the lens is more intuituve, in other words, its placement there typically makes more sense and is easier to use and quicker to get to. I've never been a fan of the thumbwheel iris.
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Old July 29th, 2006, 11:25 AM   #5
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So you can get confused with the focus ring... kidding.

Consumer cams or auto iris will judge the brightest spot in the shot and adjust accordingly. If your using zebra, and have manual iris, you can fine tune the shot to your own judgement.

It doesn't matter whether it's a thumbwheel, step rocker, or ring, they do the same thing. However, having the wheel on lens, as Mark said, is easier to work with. In a run and gun shoot (on the move or following action) is where the iris ring on lens reigns supreme as it allows you to quickly set the exposure on the fly. With auto-iris on, even on consumer cams, it's a smooth transition, but can tend to be rather slow or at a constant rate of speed. So in live event, I don't care how jerky it may seem, I need to get the shot and expose quickly, (I edit out the adjustments in post).

In productions when locked off on a set, you have the ability to control the rate and slow it down when following through a scene (similiar to a follow focus).

There is an exception with non-wheeled iris cams, like the Sony HC1. It's manual setting uses a rocker that deliberately steps up or down the exposure and that reflects back in the film. A camera like that would be better left wide open and some adaptor or external filter with finer control be use to adjust the amount of light that comes into play.

So, yeah I'm definetely interested in the XH-A1, I need that kind of iris control.
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Old July 29th, 2006, 11:42 AM   #6
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Control

You want a manual control ring for focus, iris, and zoom to have maximum control over the images you capture. With these options you control the look of the images you capture; with automatic or menu controlled systems, you are basically working within the limitations of that particular system.

You can create with greater flexibility and creativity because you are the one making the decisions, not the camera. There are many instances where you may want to over or under expose a shot/scene to create a psychological or other effect, which maybe you couldn't if you were relying on an automated system.

Iris control is also another way to control depth of field, along with shutter speed, zoom, and focus.

Basically, it's a great thing to have!!

K.
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Old July 29th, 2006, 11:49 AM   #7
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Quote:
Originally Posted by Peter Ferling
So you can get confused with the focus ring... kidding.
Peter you're not kidding completely! There's some truth to this of course. But I don't think you'd confuse iris for focus, you'd confuse it for zoom. Because the focus ring is all the way up at the front of the lens... iris ring all the way in back... the zoom ring is right in the middle, so convenient to reach for while your head is in the EVF. I meant to adjust focus... but I adjusted zoom by accident. I wish I had a dollar for every time that's ever happened to me.

I had to teach myself to reach for the lens hood for focus, because when I reach for the lens barrel I usually find the zoom ring before I find the focus ring (all of this while not looking at it -- of course when I look at it, I know which is which).
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Old July 29th, 2006, 12:51 PM   #8
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Well, I was half-right. Chris, you don't know how many littles "umphs" I've had to edit out of the clips where I'd have blur, then mysterously zoom again. Ugh! I had to refocus to see where I was at, reframe, then focus again.

With the XL1s, I was quick with the thumb to dial the iris on the camera body, and like you, also felt for the hood to find the focus ring. Zooming was done with the ol'track and wade toggle on the grip (or the lanc). I'd get close and be happy with it. Fortunately, most clinicians were patient to wait for me to get framed before proceeding with the next step. You only get one chance.

It's going to take some practice with the new location. Maybe I'm jumping the gun here, and will have reservations until I actually pick up an A1 and try it out.
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Old July 29th, 2006, 04:21 PM   #9
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I personally do not care much where the iris adjustment is located, lens or body, as long as it's a physical ring (no way would I want a cam that makes me go through menus to adjust exposure).

That being said, this is my only huge grip with the XL2 I'm currently using. It creates wonderful images. Sharp, lots of detail, smooth, lots of dynamic range, and then all of a sudden you have to re-adjust the iris while recording... and it falls appart. The electronic steps are painfully obvious even to the untrained eye and to me screem AMATEUR (that's just me though).

And being someone who does lots of events in constant changing light conditions (like rock concerts), I often need to ride the iris live. It can be transparent with a real mechanical iris such as the one on those new Canons, but unusable on such cams as the XL2. You learn to live with it, edit around it, but ultimately, I just know that this will be a key factor for me when it's time to upgrade (which should not be too far away hopefully).
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Old July 29th, 2006, 04:55 PM   #10
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In those scenarios David, I ran in Tv mode and allowed the camera to ride the iris for me. It doesn't step like it would if you do it manually. If you don't like the camera's iris selection to manage exposure, you can reach up and dial the AE wheel a little bit either way which will 'bias' the AE more to your liking.

Works pretty good.

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Old July 29th, 2006, 05:17 PM   #11
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Greg I must say I've never "risked" using the AE for a live event. There are so many extremes like flashing/strobing spolights, lots of contrast, uneven lighting, etc. that I'm just afraid something will come out wrong (overexposed faces mainly, but also mismatches between all the cameras). Have you used the AE in such extreme shooting conditions before? If so how "smart" is it?
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Old August 1st, 2006, 03:32 PM   #12
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I don't know that I would use auto iris in these environments. It can be very sensitive. I was filming in broad daylight my daughter and she had an envelope in her hand. I couldn't see any variation in the EVF but when I viewed the footage later on an HD set the iris was pumping up and down as this little white envelope move around the frame. It was very distracting. Add to that the envelope was not very bright either....it was not overexposing. But somehow when it got to the middle of the screen it would cause the iris to close.....then as it moved away from the middle the iris would open again.

I know you can set the AE exposure +/- to what you like but from a relative point of view it still would be changing as the subject changed so I don't find that particular feature all that helpful here.

I love this feature for a lot of things but you have to be very careful......

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Old August 1st, 2006, 05:15 PM   #13
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A bit off topic, but does anyone have good tips on achieving good exposure with a video camera. I'm a farely dedicated amateur, and I find it very hard to judge manual exposure from the camera viewfinder, and the lcd screen brightness is totally dependent on ambient light and so useless.

I tend to use automatic exposure while setting up the shot, and then click to manual to lock in that setting. Whenever I try to judge it by eye I usually get worst results. Do any of you professionals have any tips on achieving good exposure? For instance is it ok to zoom in on the face say and set the exposure (and focus) and then zoom back out? Are there any techniques for using zebra stripes correctly?

Sorry for the digression but it seemed like some people in this discussion were pretty knowledgeable about this kind of thing.
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Old August 1st, 2006, 06:50 PM   #14
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Hello Richard, welcome to DVinfo.

Many basic questions can be answered with a simple search. A good discussion can be found here.

http://www.dvinfo.net/conf/showthread.php?t=70332
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