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Old February 1st, 2007, 02:10 AM   #1
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HD100 ASA rating?

Has anyone done a test to find the ASA rating of the HD100? The rating or the process to find it would be great! or is it even worth doing?
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Old February 1st, 2007, 07:19 AM   #2
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I've never had to bother figuring out the ASA of a camera, because of the feedback you get in the viewfinder for exposure. Just turn the iris ring till the picture looks good. A light meter can still be useful for ensuring even lighting in your scene, though.
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Old February 1st, 2007, 08:56 AM   #3
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On these boards I have read that most people are rating it at ISO 320. However, I talked with Robert Yarosh, a JVC Sales Engineer just last week here and he said it actually can rate faster at a baseline ISO 400. Of course I imagine it depends on if you're using stock lense, relay lense etc. And what sort of look you're going for.
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Old February 1st, 2007, 09:23 AM   #4
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Jay, in my opinion David and Stephan both have it right. I've set my meter to 320 ASA to get a "general" reading, but I use it mostly for ratios. What I also do is set my Zebra to 60%-70%, and adjust the iris until the zebra starts creeping in on the key side of a face. Of course that's all dependent on what you're shooting, but it's a good place to start to combine a lightmeter and the Zone System.
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Old February 1st, 2007, 04:53 PM   #5
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Sweet! thanks ya'll. I shot a music video over the weekend and the DP was rating the camera at 200asa (stock lens w/ the color reversal setting). I only saw the LCD and it looked blown out, but the images look correctly exposed on my CRT and SD TV. I'll do some tests with that zebra setting and asa.
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Old February 1st, 2007, 05:21 PM   #6
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I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high
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Old February 1st, 2007, 10:36 PM   #7
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Probably the best way to judge is to set your zebras for 50% and expose an 18% grey card so it's just barely getting zebras. Assuming a flat gamma curve (you would need a chip chart and waveform monitor to verify this, and unfortunately full chip charts can be pricy) you should end up with a fairly accurate idea of what your ASA rating is.

Of course the lattitude of a video camera is small enough that you can't really depend on a light meter to tell you exactly how you should expose unless you've figured out how you can apply the zone system to this camera. Otherwise, you really have to just eyeball it on a scene-by-scene basis.
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Old February 2nd, 2007, 09:51 AM   #8
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Quote:
Originally Posted by Matt Setnes
I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high

I agree, too high...

john
evilgeniusentertainment.com
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Old February 2nd, 2007, 10:45 AM   #9
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Quote:
Originally Posted by Matt Setnes
I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high
It really all depends on how the gamma controls are configured. It can range anywhere from 100ASA with the gamma turned down to as high as 640ASA with the gamma cranked all the way to max.

Typically though, I would rate NORMAL gamma (cine) at around 250ASA.
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Old February 3rd, 2007, 10:42 AM   #10
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30p ASA

At a flat gamma (non-cine) at 30p I got an ASA of just under 400...but that was on my 110
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Old February 21st, 2007, 03:00 AM   #11
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Are there any official ASA Ratings from JVC?
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Old March 4th, 2007, 09:43 PM   #12
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how would one measure the asa for a given scene file?
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