On May 25, 2012, at 10:53 PM, Mark C wrote: > If I were testing the meters, I'd do the following: > > 1. Be sure to compare both meters in spot metering mode. You probably did > this but just in case... > 2. Verify what the 'spot' in the spot metering is. Put a small saucer sized > white paper plate on a piece of black foam core. With the K5 - fill the frame > with the plate and then slowly walk away from it, letting the black foam core > start to fill the frame. Keep the paper plate centered in the finder - you > will see the meter reading stay steady and then rapidly change as the plate > gets smaller than the area being metered. You can verify that the "spot" > being measured correlates the to the circle in the center of the frame. You > could do that with the Sekonic as well. > 3. Test both the K5 and Sekonic on a gray card, using your knowledge of the > size of the spots to be sure that you are only metering off the grey card. > 4. If there is a material difference in the readings off the gray card, then > test the meters off a gray card in direct noon sunlight and compare to the > sunny 16 rule. Hopefully one of the meters will comply with that. > 5. Use the meter that complies with sunny 16 to work up an adjustment factor > for the other. Well though out, but I don't think that's precise enough to get an accurate calibration. Sunlight intensity varies by the season and by atmospheric conditions. The only way to be sure a meter is accurate is to have it checked by a professional calibration service. Quality Light Metric in L.A. 323-467-2265 is among the very best. They calibrate meters for many of the DPs who work in the film industry.
Paul > 6. Spot meter off various colored items and see if the meters perform > consistently. If they vary, they may be more or less sensitive to different > colors. This can be a bugger because you have no control point. One meter may > be more sensitive to green, another to red, you can't use one to calibrate > the other. You can try the sunny 16 rule with different colors, of course.. > > Are you shooting slide film, color neg, or silver B&W? > > If B&W, I'd just go out and shoot, take notes (mental or otherwise) and > compensate the workflow. That means tweaking your metering / film ISO setting > (same thing), your development times and agitation regimen. Use the data > printed along the edge of the film as a control point for developing. If you > are shooting slide film you have to be more careful with metering. > > Here's a story about metering and slide film: > > I visited the beach with a friend of mine one day, and we both shot this > lighthouse: > > http://www.markcassino.com/newsite/portfolios/lighthouses/pages/0204l07.htm > > He had a Nikon F5 with a super sophisticated evaluative / color corrected > metering system that he relied on. I had a Pz-1p. I spot metered off the > black metal frame, did some quick zone calcs in my head, and set the exposure > manually. We both shot ISO 100 slide film (him Provia, me E100S.) My shots > came out very well - maybe 1/4 to 1/2 stop over exposed, but very usable. His > were a mess. SO taking control of metering with film is important. > > Good luck! > > MCC > > > > > On 5/21/2012 8:27 PM, Kenton Brede wrote: >> I'm making a foray into film and decided I should get a light meter. >> I bought a used Sekonic L-508 which has both incident and spot >> metering. Messing around with the K-5 and Sekonic, I found the >> readings didn't really match up. So I took a picture of the blue sky, >> the histogram was spiked in the center. I then spot metered the sky. >> I used the compensation function to dial in 3AV to bring the meter in >> line with the K-5's shutter, ISO and aperture. I used a gray card in >> the shade to meter off of with the K-5, and then matched those >> settings on the Sekonic by dialing in a -1AV for the incident reading. >> >> Does this sound like a decent calibration method? >> >> I went around metering things and taking shots with the K-5. I found >> that if I spot metered off a shaded green bush, I needed to speed up >> the shutter 2 stops to bring the histogram near center. When metering >> off a gray cloud, with silver lining, I sped up the shutter a couple >> stops to bring the histogram to center. The incident meter seemed to >> get the K-5 in the ballpark when metering in front of a tan shed, >> while the meter was facing the direction the sun. In shade, facing >> away from the sun, I generally had to slow the shutter down a couple >> stops. >> >> Does this sound like the way an accurate light meter works? I've >> never used one. >> >> Any thoughts appreciated. I realize all this hinges on the K-5 being >> accurate, and assuming the film cameras will work with the same meter >> readout as the K-5. I probably should have just purchased a new >> model, but good ones are expensive! >> Thanks, >> > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
