Mon 06-Feb-12 01:57 AM | edited Mon 06-Feb-12 12:55 PM by laddad
I have three high quality light meters, two old, one new, but all functioning with three different readings. The spread is about 1 stop. All were tested in ambient light under same the conditions. All were used in the incident light mode.
Sekonic L-758DR, new Minolta Flashmeter IV, 20 plus years old but excellent Quantum Calculight XP, 20 plus years old but excellent
Question 1: Which one is right? Question 2: Who can calibrate the older meters?
They are all right. What numbers the meter gives back is immaterial. What matters is if you set your camera to that exposure, do you get a proper exposure. So therein lies the crux of the matter. When you were using the older meters, and setting your camera to match, did you get on the money exposures, or did you get over/underexposed photos?
This is one reason I stopped even having my meters give me F-stops when I am shooting films (aka motion pictures). I just have it give me footcandles, and work from there.
Yeh I guess. I think the the Sekonic is 100% correct and the others 85%. I like consistency! If one is down, I want to use another with 100% competence. I shoot Spherical Panoramas thus lots of contrasty situations. I depend on hand held meters more than the camera meter.
Ok, well get another Sekonic. Problem solved. Or work up a compensation table for the other meters and do the math, just like we do when we add filters. Either works just fine.
Photocells age over time. Older meters will not be as sensitive as they once were. There is probably someone who can replace the cells, but I couldn't tell you who. About the only people I see using meters these days are old guys like me who came from film, and the movie guys who need to work up something before they call in the lights from the truck. And maybe the fashion guys. Everyone else is good with Matrix metering.
I probably look like a fool walking the courts and the fields with my meter before sporting events. Fortunately, I can use the spot meter on my Sekonic for most things now.
Laddad, I also have the Minolta Autometer IV. It sat on a shelf for 20 years. In April I bought a Nikon D7000. The light readings from the Minolta are identical to the camera when using a wide angle lens.
And I used a remote PC cord to connect the meter to my SB800 strobe. A meter reading of the flash yielded the same results as TTl metering with the same strobe mounted in the hotshoe of camera.
All the while, I am aware of how the angle of view and reflectivity of the subject matter can add or subtract from readings with any meter. I shot a lot of Kodachrome 64 using only incident readings from my Minolta. Kodachrome is very unforgiving about under or over exposure. But the meter always gave me professional results.
>They are all right. What numbers the meter gives back is >immaterial. What matters is if you set your camera to that >exposure, do you get a proper exposure. So therein lies the >crux of the matter. When you were using the older meters, and >setting your camera to match, did you get on the money >exposures, or did you get over/underexposed photos? > >This is one reason I stopped even having my meters give me >F-stops when I am shooting films (aka motion pictures). I >just have it give me footcandles, and work from there. > >
They are not all right. At least 2 of them are wrong if not all three. And I must emphasize this point that when the meter is right it does not necessarily give you good exposure and when it gives you good exposure it's not necessarily right. It's right when it is accurate to the standard that it was calibrated for.
This says it all, it is about the picture looking right. Incident light readings are best then Gray card reading for reflected light, Histogram will tell what is working best, but with RAW you can always tweak. Getting it right in camera save time!
Have you compared them using reflective mode? Are the results the same of different? If the same then I would also suspect the diffuser used for the incident readings. Not only photocells change over time, plastic does as well.
I would try an incident reading on a clear blue sky (no direct sun), and you should get the "sunny 16" answer.
Or... send the best meter, the Sekonic, to Quality Light Metric, 7095 Hollywood Blvd. Ste 550, Los Angeles CA 90028-8912, for calibration. Then note the difference with the others and make appropriate corrections.
My bet is that the Sekonic is correct (I've had that model for years, and it has always been perfect.)
Thu 02-May-13 12:37 AM | edited Thu 02-May-13 12:43 AM by Craig Bennett
>I would try an incident reading on a clear blue sky (no >direct sun), and you should get the "sunny 16" >answer. > >Or... send the best meter, the Sekonic, to Quality Light >Metric, 7095 Hollywood Blvd. Ste 550, Los Angeles CA >90028-8912, for calibration. Then note the difference with the >others and make appropriate corrections. > >My bet is that the Sekonic is correct (I've had that model for >years, and it has always been perfect.)
I have a Sekonic L-478DR and this is exactly how I checked mine!. The Sunny 16 rule provides a very good controlled test IMO. My meter was dead on....as were my cameras using spot metering and grey card under the same condition.
I have a huge respect for Joe McNally...he is a master and IMO a league of his own with regards to lighting. But there are good reasons to use a light meter. If all I did was shoot with Speedlights using TTL, then I might see it, but for studio work, there is not substitute. Also, with setting up formals and using my speedlights on manual or my monolights, then I use my lightmeter to set the power levels, set my camera on manual leave it and shoot without worrying about what the camera is doing with the flash. This brings consistency to the session.
It's my understanding that Sekonic bases their exposure on a 12% reflectance. Most of the rest of the world bases their exposure on 18% reflectance. IIRC, that's a 1 stop difference. This Photo.net discussion goes into 18% vs 12%: http://photo.net/large-format-photography-forum/006kMK?start=10 The FM-IV has a tiny rheostat in the battery compartment that gives U some adjustability. The important thing is that U know what is the correct reading for your circumstances. I wouldn't bother to send the new Sekonic in for calibration, unless U have some reason to suspect it's accuracy, such as having been dropped or abused in some other way, (U did buy it new?) It's almost certainly as correct as it left the factory. If it were me, I'd send the Quantum, & the FM-IV to Quality Light Metric for calibration. George Milton (I've gotten terrible w/ remembering names these days. I think that's his name.) @ QLM is one of the finest, most conscientious, accurate, & honest people around. U will get 2 meters back that are accurate or U will have a damn good explanation why not, that U can believe. Call him 1st to see if he works on the Quantiums. The worst thing about is the FM-IV is that it has about a hundred different switches, which gives about ∞ combinations to be misadjuste The best thing about my old Quantium was that it had a flat circular calculator that I could use to plan exposures with, instead of my head & fingers. Best Wishes, Jay Drew
Even if you consider the FM-IV and the 758 are calibrated differently the readings should be very close to each other.
In incident mode the 758 is calibrated for C=340 and the FM-IV for C=330 the sekonic would read 0.043 stop lower. In reflected mode the 758 is calibrated for K=12.5 and the FM-IV or other Minoltas were calibrated for K=14 and the Sekonic would read 0.16 stop higher. Not anywhere near a 1 stop apart.
>I have three high quality light meters, two old, one new, but all functioning with three different readings. The spread is about 1 stop.
I have a 6-month-old Sekonic 758 Cine, and it's always right on (exposure-wise). I bet yours is the same. I've got three Sekonics, and even the model from the 1990's is within a quarter-stop of the new one.
If you really want to, you can duplicate the tests the meter boys do, measure Dmax, Dmin and density and so forth. Or you can go out and take photos using the exposure info from your meters, and see which of your meters is most accurate.
Sekonic will repaire and calibrate their meters, I think.
If I was you, I'd keep the most accurate meter and sell the other two. If you want a backup meter (I use my next newest Sekonic), buy a new one you know is accurate. (I tested my meter at the store before I bought it. I know the accuracy of my D4 meter, and the Sekonic lined up well with that...the Sekonic will give me greater granularity, though.)