Comparing photos

OldNick

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Sep 3, 2006
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Western Australia
I was wondering if you guys has a set of rules for photographing lights. Targets, distances, camera settings. I see this as being used when comparing photos posted on the web.

Thanks for any help
 

lightningbug

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Apr 1, 2006
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Posters usually will note the distance from the light to the target background in their post.

There is no set distance, but I think most of us prefer to shoot beam photos @ 1 meter or less.

For throw examples, most pictures are taken outdoors and the distances vary wildly.
 

OldNick

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I am starting to feel like the Light Police here.:rant:

There was a thread that tried to address the problems of lack of uniformity, but it died months ago AFAICS, and there is a Poll/thread about photo methods.

I am happy to see outside shots, simply showing the view. But isn't comparison important? Ican make a LED or light look awful different by simply mucking about with the camera.

lightningbug said:
Posters usually will note the distance from the light to the target background in their post.

There is no set distance, but I think most of us prefer to shoot beam photos @ 1 meter or less.

For throw examples, most pictures are taken outdoors and the distances vary wildly.
 

Somy Nex

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Penang, Malaysia
just my humble opinion but the methodologies for lux, lumens, and "light units" are there, and if you want an absolute comparison, those are the best units to use, even though there are flaws and difficulties associated with them, particularly the latter two. Even something as scientifically defined (and you'd think, "straightforward") as lux and lumens requires calibration and specific methodologies to be used to be comparable to one another.

so, with so many different factors surrounding beamshots, you can't really make beamshots comparable across the board for everyone, as there are differences in actual sensitivities between different brands of cameras and films, and even between models of the same camera using different CCD sensors (most of us use digital now). ISO 80 on one camera may be equivalent to ISO120 on another, or whatever (just an example). then there's also shutter and aperture speeds, and distance from target and other external factors such as the lux lottery and the scenario used for the beamshot (white wall & small room vs. large open area & green leaves vs. ???), and blah blah blah.

at best, you can standardize among your own beamshots, and hope one of the lights you own is one which the person seeking information also owns or has a question about. but in essence, that's really about it.
 

Lips

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Mar 14, 2005
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Louisiana - USA
Just list the info.

PhotoShop is a PITA!



Unerexposed Beamshots
Manual Mode 9ft
Laser for centering Vent in Ceiling
ISO 100 1/13 sec F3.2


Beamshots0506FF.jpg



.
 

OldNick

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Joined
Sep 3, 2006
Messages
130
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Western Australia
Lumens seem to be the unit of choice, for all their possible faults. However, a Lumen does not help measure how bright a beam you get from a torch. You need to know how small an area the beam covers as well.

And _there_ you get problems. beam degrees vary widely fro claimed figures, to th extent where the accepted measure is the angle of half fhe beam width at which the light has reached half its peak value, but I saw one lens that gave the totla width of fhe beam when the light had fallen to almost zero. This made it about 1/4th as wide as everybody else's for the same "12 deg" beam.
I feel that while cameras will be different, it will be within an f-stop for given conditions. This is better than nothing.

As I said, "targets, distances, cameras settings etc". That was my point. If you set up an agreed set of targets, at a known distance, with the colours also agreed upon, you can elliminate a lot of subjectivity.

It seems to me that every reply has said that one part won't work, because the other part gets in the way.......so think about them all and see what happens! The biggest factors here are the human eye and brain.

Somy Nex said:
just my humble opinion but the methodologies for lux, lumens, and "light units" are there, and if you want an absolute comparison, those are the best units to use, even though there are flaws and difficulties associated with them, particularly the latter two. Even something as scientifically defined (and you'd think, "straightforward") as lux and lumens requires calibration and specific methodologies to be used to be comparable to one another.

so, with so many different factors surrounding beamshots, you can't really make beamshots comparable across the board for everyone, as there are differences in actual sensitivities between different brands of cameras and films, and even between models of the same camera using different CCD sensors (most of us use digital now). ISO 80 on one camera may be equivalent to ISO120 on another, or whatever (just an example). then there's also shutter and aperture speeds, and distance from target and other external factors such as the lux lottery and the scenario used for the beamshot (white wall & small room vs. large open area & green leaves vs. ???), and blah blah blah.

at best, you can standardize among your own beamshots, and hope one of the lights you own is one which the person seeking information also owns or has a question about. but in essence, that's really about it.
 

OldNick

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Joined
Sep 3, 2006
Messages
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Location
Western Australia
But I have had two posters (well, me and one other) both saying their shot portrayed "what they saw" .......with 6 f-stops of exposure difference between them. Different lights. Different targets, but basically two LED lights, both in the multi-watt range and above 100 Lm each, with similar beams, shot in the dark. But we said we both posted what we saw _and the photos were completely different! We _did_ post the settings, and they were way off; 6 f-stops. So the photos looked completely different, and another viewer would look at one shot and say "well that's MY torch!" because it looked so bright.

Lips said:
Just list the info.

PhotoShop is a PITA!



Unerexposed Beamshots
Manual Mode 9ft
Laser for centering Vent in Ceiling
ISO 100 1/13 sec F3.2

.
 
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