Bill, I just read the specs on the Sekonic C-500 color meter. Besides the cost ($1,000) it apparently does not read below 2,300K. From a real world film perspective, this is probably not be an issue. It appears that 2000-3000k is the quality of light seen at sunrise or sunset.
Any thoughts anybody??
Film has latitude. Shutter speeds are within tolerance if they are ±30% of the marked speed. ISO, exposure meters and guide numbers are starting points. They are not arbitrary. You tailor the ISO, the filter factor, the guide number, the exposure meter, the flash meter and the color temperature meter for your personal preferences (if you shoot for your satisfaction) and to your clients expectations if you are shooting for someone.
if a colour meter isn't matched to a particular film then what is the point of your test.
Each colour film has RGB layers but what is the actual wavelength range of those layers? I bet they will not be single wavelengths because if they were, they would remove a lot of colour information from the subject. So does your colour meter work on single wavelengths for each colour and if not what range does it work over and do those ranges match the film RGB ranges exactly. I think not. So what does does your colour meter prove? Nothing. It always comes back to practical evaluation and that is done using ONE meter so that your personal ISO speed suits that meter. If you have other meters which don't give same readings then you have to test those as well. There are no short cuts.
p.s. digital cameras have white balance so why don't light meters?
Last edited by percepts; 10-Jul-2009 at 10:19. Reason: typo
Hmm. All I know from my own experience is that my B&W proofs - made consistently, all with the same exposure, development, etc. - are consistent. They all look fine. So if my Pentax Digital is goofy, then it's accurately reflecting a goofy universe.
"Close Enough for Photography."
I guess I'm missing the practical application of bglick's analysis. What, practically speaking, should we do differently?
Bruce Barlow
author of "Finely Focused" and "Exercises in Photographic Composition"
www.brucewbarlow.com
I find my inaccurate meter compensates for my faulty shutter speeds. And my overcompensation for reciprocity failure usually makes up for forgetting the bellows extension factor. I think I'm finally perfecting my technique...
"I love my Verito lens, but I always have to sharpen everything in Photoshop..."
Doesn't the K-factor also influence the reading a meter might give. Some manufacturers seem to clearly state their K-factor; others seem to not.
but... too much scientific analysis ruins the fun for me. Somehow I seem to get good, accurate, and consistent negs despite using a collection of potentially inaccurate, imprecise, and poorly calibrated meters. Perhaps I should have taken the "don't bother reading" option offered in the OP
> You did not even maintain a constant change in EV - the figures are jumping all over the place, at a much greater magnitude than the change in K. For a clean test, only the tested parameter would be variable - a constant growth in EV would be the absolute minimum for an amateurish approximative test.
Sevo..... just to clarify this post...
1) I was not paid by you, or an outside source to run this test. This short test was to confirm a suspicion I always had.
2) The results of this short test, speak volumes about the variance in light meters, plain and simple. Is this a perfect test? Hell no, but it proves an obvious point, their is huge errors between different light meters. Certainly far above the +/- .1 stops advertised.
3) The information I shared in this post was as a courteousy. I am sorry if I did not spend weeks and thousands of dollars producing the level of information you would classify as a bear min. for even an amateurish study. You are welcome to do such, and share with the list. Or if you want to fund the study to be sure it meets your min. amateurish standards, just send me $5k and I am capable of performing such.
> and assumes that among them only color temperature had any influence on the results.
Sevo, this claim was never made, the variance in readings in this small sampling can be a result of light levels AND/OR color temp... my guess is, it's both. Accept the data for what it is, draw your own conclusions.
Rob, I would say the number of times landscapes will produce color temp below 2300 is is very rare. So, I would not be concerned about it. If you take this route, run a test with 35mm chrome film against an exposure chart....compare with an exposure meter. If you do such, I would understand why you would not post the results to this forum, but I would sure appreciate if you shared the results with me off list....
> You tailor the ISO, the filter factor, the guide number, the exposure meter, the flash meter and the color temperature meter for your personal preferences (if you shoot for your satisfaction) and to your clients expectations if you are shooting for someone.
1) I never once heard a client suggest a specific tailoring of these variables, they want a properly exposed image...
2) Considering most pros know very little about this, I doubt the avg. photog is tailoring for these issues. The assumption is, exposure meters are accurate. Now that most of the world is digital, the results are right on the screen after capture, not a huge issue anymore.... except if you shoot 8x10 in the field and the results are not seen till weeks later...
the one exception to this rule is the studio shooters who spend days tweaking their tools. This forum is not heavy into studio shooters, hence my comments.
> if a colour meter isn't matched to a particular film then what is the point of your test.
Argggggg..... I may have to remove this post. As mentioned several times above, this test demonstrates that exposure meters vary tremendously in exposure readings over different color temps and/or different EV values. That's it! Get it? Nothing else, forget film.... this is about exposure meters. If one meter reads 7.5 EV, and another reads 8.5 EV, they both can't be right.... get it? It's that simple !!! They may each be off by .5 stops, or one could be off a full stop, and the other nutz-on. Or it can be even worse... This 15 minute test did not determine where the errors lie, it only exposed the fact the errors exist.... make sense now? OK?
> So what does does your colour meter prove? Nothing.
thats correct, but what you fail to realize is, I never suggested the color meter was a reliable standard to test against. So once again, lets try in CAPS this time....
THIS TESTS DEMONSTRATES THAT EXPOSURE METERS, FROM DIFFERENT MANUFACTURERS, RECORD VERY DIFFERENT EXPOSURE VALUES UNDER DIFFERENT COLOR TEMPS AND EV RANGES!
Now, is this clear yet?
> I guess I'm missing the practical application of bglick's analysis. What, practically speaking, should we do differently?
Bruce, I am not suggesting anyone do anything different. I tested 4 meters and offered the results to the list, which turned out to be a huge mistake. What you do with the data is your business. If you have perfect exposures on every shot with your film and meter, then you have nothing to be concerned about... why would you change anything?
I am not suggesting any changes to exposure techniques based on this test, because I don't have sufficient data to suggest such, I simply shared the results to demonstrate the errors..
All I can say is, it's insane to expect exposure meters to be within +/- .1 EV (what their specifications state) over a wide range of color temperatures and EV values. They can often be a full stop off. Whether this is of concern to you as a photog. is personal preference, often based on the type of photography you do, and how picky you are about your results.
too much scientific analysis ruins the fun for me. Perhaps I should have taken the "don't bother reading" option offered in the OP
yep, you got that right..... hence why I put that in the 2nd line of the post.... but, at least you were one of the few who comprehended and acknowledge this, so Kudos to you Brian....and congrats on your great exposures. And you are right, if you have having fun, and happy with your exposures ignore these type posts....
In my case, I often can spend thousands of dollars getting to a location for a shoot, and while bracketing is the ultimate solution to this issue, with 810 it can be quite costly.... so I try to gain as much knowledge as possible to increase my chances of success..... I know, call me crazy, ..... I just can't help myself....
What did you expect to learn from your test? It seems you thought these light meters are scientifically calibrated devices. They ain't. Once you know that then you will understand the futility of your test. Get it?Originally Posted by bglick
> What did you expect to learn from your test?
It's called "confirmation" Percepts.... get it? I was confirming my suspicion. Or maybe the sensible position is, accept suspicions, don't confirm... that might be your style....
> It seems you thought these light meters are scientifically calibrated devices.
It seems you still have not comprehended my post. I knew these meters were only calibrated and tested at one color temp. Hence why I ran this simple test. I knew there would be errors at different color temps and EV ranges, but how great would the errors be ? That's what the test demonstrated, get it now?
> They ain't. Once you know that then you will understand the futility of your test. Get it?
You are right, they "aint" scientifically calibrated devices. That alone would not answer the question of, how far do these meters drift when they are used outside their calibration range.... get it now?
Let me know if you are still confused....
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