My A1 iris doesn't close completely at DVinfo.net

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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 May 13th, 2007, 09:00 AM   #1
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My A1 iris doesn't close completely

Hi,
I'm Italian, I bought a XHA1 but I've discovered that I can't fully close the iris. After F9.6, if I turn the ring the lcd says "closed" but I can still see something in the dark, and if I put the gain on it's even more obvious that the iris is still a little open. Does anyone else have this problem?

Thanks
Alessandro
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Old May 13th, 2007, 09:05 AM   #2
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Interesting. You're turning the aperture ring in the manual mode, yes? What happens in the fully auto mode? On all the cameras I've looked at the iris closes completely as much to protect the CCDs in very bright sunlight as well as to give correct exposure at apertuures smaller than the v'finder readout suggests exist.

tom.
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Old May 13th, 2007, 09:09 AM   #3
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Originally Posted by Tom Hardwick View Post
Interesting. You're turning the aperture ring in the manual mode, yes? What happens in the fully auto mode? On all the cameras I've looked at the iris closes completely as much to protect the CCDs in very bright sunlight as well as to give correct exposure at apertuures smaller than the v'finder readout suggests exist.

tom.
Of course I am in manual mode, otherwise how could I close the iris down?
In full auto the iris ring of course is disabled.

Alessandro
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Old May 13th, 2007, 09:20 AM   #4
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If the iris was disabled in the auto mode you'd get some gross under and over-exposure Alessandro, unless you were in the aperture priority mode.
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Old May 13th, 2007, 10:03 AM   #5
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Originally Posted by Tom Hardwick View Post
If the iris was disabled in the auto mode you'd get some gross under and over-exposure Alessandro, unless you were in the aperture priority mode.
I believe there is a misunderstanding problem... My problem is that I can't close the Iris completely to black, but it stops after F 9.5 and stays a little open. Try to understand whay I'm saying please...

Alessandro
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Old May 13th, 2007, 01:37 PM   #6
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mine closes to black with no problem.
in auto, you can hit exposure lock and turn the iris ring.
try that.
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Old May 13th, 2007, 02:51 PM   #7
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I noticed a while back when I first got the A1 that attempting to close the iris in EXP Lock or manual mode, it gets to f9.5... still not closed completely (can still see image)... continue turning the iris ring some more & eventually it completely closes, all the while still giving a reading of f9.5.

I thought it was strange, but it didnt bother me since I'd never find any use shooting that way to begin with.

Bill
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Old May 14th, 2007, 02:34 AM   #8
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Bill, that's how my old VX2000 worked. There were no further v'finder readings after f/11, but that didn't stop the camera happily shooting away at f/16, f/22 or even f/32. Of course to shoot at these very small apertures you'd have to ignore the silent scream for you to punch in some ND filters, but the camera was clever enough to do this to give you correct exposure at the expense of sharpness.

Diffraction losses are far more apparent with small chips, small apertures, short focal lengths and of course high definition. The PDX10 camera stopped you shooting at anything smaller than f/4.5, and the Sony A1 stops closing the aperture at f/4.

The canon A1 goes to f/9.5, but in reality of course you shouldn't shoot at anything less than f/4, especially with the wide-angle in place. I'm still not sure why Alessandro Nucci's camera doesn't close the aperture blades fully, but then my Z1's don't either. But on the Z1 a shutter drops down behind the aperture blades to protect the chips.

tom.
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Old May 14th, 2007, 12:20 PM   #9
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Tom, what I meant was that the image stayed the same after reaching f9.5 until after a few more turns, then the iris finally closes completely.

Maybe this is what Allesandro is experiencing... except he didn't continue to turn the iris ring.

Bill
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Old May 14th, 2007, 05:18 PM   #10
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Maybe this is what Allesandro is experiencing... except he didn't continue to turn the iris ring.
I turned the ring many times after F9.5 but it stays a little open even when "closed" comes up on the LCD reading.

Alessandro
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