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Author Topic: H3DII-39 meter inaccuracy  (Read 1487 times)
epines
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« on: November 07, 2012, 06:11:41 PM »
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I recently sent my H3DII-39 to Hasselblad (Denmark) to have the IR filter replaced, and now that it's back I'm noticing something that wasn't there before (I believe this has been discussed elsewhere): the meter does seem to underexpose pretty seriously. I have to dial in 1 - 1.3 stops extra exposure to get it to shoot at a zone 5 / middle grey. Shooting a blank wall at the meter's reading (which should produce a middle exposure) produces an exposure around zone 3.7 or zone 4. Shooting around 1.1 stops above the meter's reading produces a histogram right in the middle. Anything I can do about this?

I swear it was accurate before I ever sent it over, which makes me think it can be adjusted.

thanks
ethan
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epines
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« Reply #1 on: November 09, 2012, 10:16:00 AM »
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Follow up: Upon a second round of quick testing, it seems that I have to dial in +0.3 - +0.7 (rather than +1.0 - +1.3) to get a centered histogram when shooting a blank wall / sky / surface. My Canon 5D MkII also seems to need the identical compensation, so perhaps this is the norm for digital cameras. Strange / annoying.
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Gel
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« Reply #2 on: November 10, 2012, 06:12:02 PM »
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The cameras metering system only sees an average number, which is 18% grey.

Point it at a white wall and you'll need to over expose by two stops.
Point it at a black wall you will need to under expose by 2 stops.

When you point your camera at a scene the camera will base the exposure on an 18% grey average.

This is really base level photography 101. Read up on it.
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Chris Giles Photography
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« Reply #3 on: November 10, 2012, 08:50:19 PM »
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Follow up: Upon a second round of quick testing, it seems that I have to dial in +0.3 - +0.7 (rather than +1.0 - +1.3) to get a centered histogram when shooting a blank wall / sky / surface. My Canon 5D MkII also seems to need the identical compensation, so perhaps this is the norm for digital cameras. Strange / annoying.

http://www.rawdigger.com/houtouse/lightmeter-calibration
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deejjjaaaa
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« Reply #4 on: November 10, 2012, 08:50:46 PM »
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The cameras metering system only sees an average number, which is 18% grey.

which in most cases is not 18%.
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Chris Livsey
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« Reply #5 on: November 11, 2012, 05:57:33 AM »
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Follow up: Upon a second round of quick testing, it seems that I have to dial in +0.3 - +0.7 

Which is an average "correction" of 0.5 stop which is "correct"

http://www.bythom.com/graycards.htm
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Chris Livsey
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It's not what you look at that matters, it's what you see.
epines
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« Reply #6 on: November 12, 2012, 11:37:51 AM »
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The cameras metering system only sees an average number, which is 18% grey.

Point it at a white wall and you'll need to over expose by two stops.
Point it at a black wall you will need to under expose by 2 stops.

When you point your camera at a scene the camera will base the exposure on an 18% grey average.

This is really base level photography 101. Read up on it.

Dear "Gel":

I know how a camera's meter works. And to return the condescension:

Point it at a white wall, and you'll need to overexpose by two stops to make it white.
Point it at a black wall, and you'll need to underexpose by two stops to make it black.

I was talking about making that blank wall, whatever its tonality, a middle grey. If you'll read my posts rather than feeling self-important, you'll see that I understand that no matter what the tonality of the blank wall you point it at, the meter should render it 18% grey, i.e., middle grey. So I was expecting a centered histogram when shooting at the meter's reading. And I was getting a histogram that was about a stop below the center. Thus my assertion that the meter was underexposing.

Why don't you take a look at my work, and then we can discuss again whether I should read up on photography 101.

www.ethanpines.com

 
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epines
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« Reply #7 on: November 14, 2012, 10:08:57 AM »
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Which is an average "correction" of 0.5 stop which is "correct"

http://www.bythom.com/graycards.htm

Chris --

This is exactly what I was talking about. Thanks for the explanation. Apparently meters actually measure around 12% gray. You don't learn something new every day, but on this day I did.

ethan
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Chris Livsey
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« Reply #8 on: November 14, 2012, 01:37:43 PM »
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Thank Thom for writing clarity, although he does take a while to get there sometimes.
My credit is for knowing where to look  Grin
Happy to help.
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Chris Livsey
http://www.flickr.com/photos/red_eyes_man/

It's not what you look at that matters, it's what you see.
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