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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 March 6th, 2009, 06:50 AM   #1
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2 camera exposure

I will admit we are still using exposure in automatic mode.

However I am noticing that one camera will have a "lighter" yet correct exposure while another has a "darker" yet correct exposure. Forgive my ignorance but if I remember anything from still photography, it's that being zoomed in farther requires more light.

So how do I correct this? If we go to manual mode, it's not like I can just tell the other camera "shoot these settings" because we're going to be filming two shots, a medium and closeup or whatever.

Attached see two examples. It's not even consistent as to which camera (zoom level) creates which exposure issue.

What I'm showing here is really just a one frame grab but as I watch the footage, the differences are a little more obvious.
Attached Thumbnails
2 camera exposure-exposure_1_cu_lighter.jpg   2 camera exposure-exposure_2_cu_darker.jpg  

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Old March 6th, 2009, 07:02 AM   #2
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When you shoot on auto and zoom in, the exposure can and will change because the average brightness of the background changes. Like if you first have a wide shot with sky in it the exposure will be a bit dark. After you zoom in and cut out the sky and get more dark riverbank in the picture the exposure lightens, further zooming has only the fisher and light water and exposure gets dark again. I hope you get my drift here.

The only way to have consistent exposure is to shoot on manual where the exposure stays put. If you are zooming in very deep, choose an f-stop which is available also at the zoom tele end, otherwise the will be some darkening at the tele end (problem with cheap long zooms, they do not hold max aperture all the way...)
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Old March 6th, 2009, 09:36 AM   #3
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In the first shot, look at the sun on the guy's forearm. The second shot is more backlit. You really need to get off auto exposure.
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Old March 6th, 2009, 09:51 AM   #4
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I agree with Bill. And not only that, all four of those shots looks like there may be some lens diffraction going on. Look at the trees in the background for example. Then again there's not much detail at all in those shots. Were you using ND? If not you should, plus trashing auto & open up the aperture manually.
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Old March 7th, 2009, 12:37 AM   #5
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also, if possible, shoot from a different angle so the main subject isn't in shadow and the light is more even. or hire a lighting crew (ha ha). i find choosing the right angle/light in the first place is easier than struggling with two different exposures at once.
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Old March 7th, 2009, 04:33 AM   #6
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Throw it in manual, lock your shutter at your appropriate speed, turn your gain down to -3 or 0 (since it's bright) and dial in your aperture using the exposure meter at the top left hand side of the LCD.

If the meter is always in the middle for both cameras, then it's pretty much "shooting the same settings". Only variable is the aperture which you adjust to correctly expose.

Like Bill B. said, use ND filters first before stopping down the aperture.
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Old March 7th, 2009, 10:24 AM   #7
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Thank you everybody, I am reading and digesting. I appreciate *all* of your comments and help.

Quote:
Originally Posted by Randy Panado View Post
Throw it in manual, lock your shutter at your appropriate speed, turn your gain down to -3 or 0 (since it's bright) and dial in your aperture using the exposure meter at the top left hand side of the LCD.

If the meter is always in the middle for both cameras, then it's pretty much "shooting the same settings". Only variable is the aperture which you adjust to correctly expose.

Like Bill B. said, use ND filters first before stopping down the aperture.
Awesome advice. I think I got over my fear of manual gain and focus yesterday next time we shoot we'll try manual exposure too.

2 questions concerning above, and shoot me if you must, but:

1) any pointers (or web links or "hey, go google XYZ your answers lie within) on choosing a shutter speed?

2) If I choose a shutter, and then constantly fiddle with the aperture using the meter display as my "bible", couldn't I achieve the same thing by choosing a shutter speed and just shooting shutter priority? Won't the camera also "keep the meter in the middle?" I realize that over time I'll get more comfy with the settings, and, choose different settings for different purposes, but for filming live action where I either got the shot or I didn't, I'd like to keep things as simple as possible at the beginning.
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Old March 7th, 2009, 12:28 PM   #8
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If you're shooting 24f the shutter speed needs to be 1/48; if you're shooting 60i, then it needs to be 1/60. It's not a still camera. If you use a shutter speed different from the standard, you will get blurring and strobing if you go slower and other types of interesting effects if you go higher, although you can go a bit higher easier than lower with nothing too noticeable. You go too high and some types of motion may appear to slow or stop. It's much better to use the standard shutter speeds and ND filters. In addition to the two built-in filters, I have an ND.3 for my mattebox that I use outdoors in bright sun so I don't have to stop down the lens so far. It seems to look better in the mid-range.
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Old March 20th, 2009, 09:39 PM   #9
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Thanks for all the info, guys. We have done two shoots on full manual now. When we got to our first shoot, there was hard sun behind a fog, so it was actually really bright... and like morons we forgot about the build-in ND (and hadn't acquired any ND filters yet)... so we set the gain to -3 and had to bump the shutter speed all the way up to 1/420 in order to get some head room on different angles.

We were able to shoot at 1/48 today though in normal outdoor lighting conditions by using the built in ND and also, it just wasn't as bright.

Again, thanks a lot for the help. Am investigating ND filters now but in the short term will use the built in.
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Old March 21st, 2009, 04:08 AM   #10
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When shooting a scene you usually do not need to change the exposure during the take. If you use auto it might and will change the exposure, but often it is a mistake! Reason: light remains the same, but the ratio of dark and light areas in the picture change and the camera interpets this as light change, but it is not! This is exactly the reason you should shoot on manual if possible. Same thing with white balance.

And yes, there is very seldom any reason not to use the standard shutter speeds. ND filters are designed so that even in bright snow scene the darkest filter and smallest aperture are enough. At least never use anything shorter than half the standard (1/120 for 60i) of your footage will look funny.
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