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Old Jun 25, 2010, 8:11 PM   #1
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Default Why light meters?

Excuse my naivete but why do some photographers use light meters? Are the built-in "reflective" light meters in DSLR's "not good enough"? In studio setups I can understand (e.g. to check ambient light, light from light sources..etc.). But I've seen photographers working outside taking portraits use light meters too. Would having one be overkill for a hobbyist?
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Old Jun 25, 2010, 9:45 PM   #2
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Any integrated camera reflected light meter can be fooled in complex lighting situations such as one with very bright and very dark areas so some photographers may use a hand held incident light meter in critical situations. This measures the light falling on the scene rather than the light reflected by the scene and may give a more accurate reading. The incident meter has to be read at the subject which is not always practical. You can simulate an incident light meter with your camera by taking a reading off an "18% gray card" which is available in most photo supply stores.
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Old Jun 25, 2010, 11:05 PM   #3
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That and for older cameras without light meters. Or to dial in a flash setup without firing a single shot.
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Old Jun 25, 2010, 11:53 PM   #4
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Quote:
Originally Posted by pbjunkiee View Post
... Or to dial in a flash setup without firing a single shot.
How do you do that ???
-> Most lightmeters I've used need the flash(or flashes) to be fired in order to measure...

http://shutterbug.com/equipmentrevie...07lightmeters/

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Old Jun 26, 2010, 12:01 AM   #5
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the test button, you dont shoot an image, you just fire the flashes
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Old Jun 26, 2010, 7:46 AM   #6
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Bob,

Can you further explain how using an "18% gray card" would simulate an incident meter reading? Is it because the card is non-reflective? Would any card still not reflect light?

And yes I do agree...we can't always whip out our $700.00 Sekonic incident meter in every situation. Come to think of it we can't always use the gray card either but is a cheap alternative.

Having said that I might one day invest in a Sekonic light meter as I would like to try shooting portraits with a studio lighting setup. A "basic setup" with maybe 1 Elinchrom umbrella, 1 Elinchrom softbox, perhaps a Lastolite reflector...and go from there...

Most of the time I guess I'll just keep taking my chances with the built-in meter in my D300. Seems to be doing a good job the majority of the time.

UPDATE: Just looked on the Henry's Camera website for gray cards (http://www.henrys.ca/11556-CPM-GRAY-CARD-2-PACK.aspx). Mentions how even these cards are reflective but at 18% (which is at which all meters are calibrated...built-in or external). I guess 18% is an acceptable level of reflectance?

And thanks NHL for posting the link to that article. Answers my question of "why an external meter?" I guess using a gray card is a decent cheap alternative for certain situations (e.g. not in studio).

Last edited by BDD; Jun 26, 2010 at 8:03 AM.
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Old Jun 26, 2010, 8:17 PM   #7
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The camera needs to have an auto exposure lock function as well as a spot meter mode. You would place the gray card facing the principle light source then point the camera at it then use the auto exposure lock function while in spot meter mode so that the card fills the spot circle. You then compose the picture and shoot while the exposure is locked. Check your user manual to see how the exposure lock could be cleared by itself such as when the exposure meter goes to sleep. This also works for flash if your camera also has flash exposure lock mode.
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Old Jun 26, 2010, 10:55 PM   #8
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Thanks Bob. And while we've mentioned spot metering can you (or any one else) tell me why some one would need an incident light meter (e.g. Sekonic 758 DR) that can spot meter when shooting outdoors? Could you not still use one w/o spot metering outdoors (e.g. Sekonic 358)? Is the 758 worth the extra $80.00 (assuming you buy the $200.00 PocketWizard transmitter to add to the 358)?
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Old Jun 27, 2010, 8:17 AM   #9
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You would get a hand held spot meter for the same reason you would use spot metering mode on your camera: you want to meter on the subject and exclude any surrounding areas that could influence the exposure reading.
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Old Jun 27, 2010, 10:32 AM   #10
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In a DSLR sure. I understand that of course. But with an incident meter? The incident meter is usually placed on the subject any how (e.g. under subjects chin). I don't see how having a spot metering function on an external meter would be necessary. Photographers have been using meters w/o it for years.
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