Photo Engineer
Allowing Ads
Keith;
The lamp in Kodak spectrophotometric work is set to a common output value. We derive everything from that very highly stabilzed and calibrated light source; however release speed is tested at the correct degrees Kelvin. Color speed tests are also done at the correct degrees Kelvin and at each segment of the spectrum, R/G/B, so you can be assured that you are getting daylight and tungsten products balanced correctly.
As for the example above, the best safelight is in the white (clear) area to the right of center, and that is how to pick a safelight for a given product.
Now, some additional information. Let us suppose that a green sensitizer causes low contrast in the green region but you have high contrast in the blue region. Your image will be mismatched in color/tone scale. This is rare but does happen. Therefore a full working wedge spectrogram used for engineering purposes looks like the one I posted above. A line drawing will not show you contrast as a function of wavelength, just speed. Both are important, but speed vs wavelength is only useful if the photo engineer has done his job and equalized contrasts.
IMHO, for the true professional photographer, a photo of a MacBeth color checker is sufficient to reveal the good and bad points of a given film product.
Peter;
I'm not sure how to reply to your comment. Of course it is correct, but seems to be a non-sequitur in the context of the preceeding posts. Can you elucidate? Thanks.
PE
The lamp in Kodak spectrophotometric work is set to a common output value. We derive everything from that very highly stabilzed and calibrated light source; however release speed is tested at the correct degrees Kelvin. Color speed tests are also done at the correct degrees Kelvin and at each segment of the spectrum, R/G/B, so you can be assured that you are getting daylight and tungsten products balanced correctly.
As for the example above, the best safelight is in the white (clear) area to the right of center, and that is how to pick a safelight for a given product.
Now, some additional information. Let us suppose that a green sensitizer causes low contrast in the green region but you have high contrast in the blue region. Your image will be mismatched in color/tone scale. This is rare but does happen. Therefore a full working wedge spectrogram used for engineering purposes looks like the one I posted above. A line drawing will not show you contrast as a function of wavelength, just speed. Both are important, but speed vs wavelength is only useful if the photo engineer has done his job and equalized contrasts.
IMHO, for the true professional photographer, a photo of a MacBeth color checker is sufficient to reveal the good and bad points of a given film product.
Peter;
I'm not sure how to reply to your comment. Of course it is correct, but seems to be a non-sequitur in the context of the preceeding posts. Can you elucidate? Thanks.
PE
