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Message: <blockquote data-quote="Surveyor" data-source="post: 1380310" data-attributes="member: 50720">While reading Elkcub’s description of, apparently, very well executed measurements of Henry’s photos, the trend intrigued me.  Since I did not know Ed’s monitor settings, I used a standard D65 (6500K) setting and the RGB standard gamma value of 2.4. Most monitors, I believe, are set to either 6500K or 9300K and most end up with gamma settings of anywhere from 1.6 to around 2.2, especially if using Photoshop custom calibration, or similar, to match cameras. I think this accounts for the couple of percent difference in the transmission values when I convert from RGB, a monitor adjusted reference system, to the CIE 1931 standard color model. My level percentages were obtained from the CIE luminance value. I have attached a couple of images of the results of the conversion. These results track Ed’s analysis very well indeed. The only additional comment I might make is, though the FL and SE end up at the D65 neutral point, they still represent a very small warm shift from the reference. Since these measurements were made on a monitor, the resultant color temperature is no surprise. If these same pictures were analyzed on a monitor with an accurate color temp setting of 5000-5500K, it appears they would approach a spectrometer look.  The color shift of 250K is very representative of what I see in spectrometer measurements of the best alpha binoculars, mainly due to the filter effect of the transmission curve since most seem to peak around 600nm and roll of in varying degrees on either side. I have attached a plot of a spectrometer output of the sun in the north sky at noon as applied to the transmission curve of an older Trinovid from another project I am working on. Don’t get excited about the 100% binocular transmission in this chart, color temperature measurements are normalized to peak=1. The one thing that surprises me is that the transmission levels from photos would indicate an average transmission value and, based on my experience, these values are more typically the peak response of the curve. There may be some monitor automatic gain control issues to contend with. From these preliminary results, it is apparent that Henry’s protocol deserves a lot more effort. From the results so far, this appears that it would be a very good predictor of differences in optic transmission and bias. It may even turn out to have some value in absolute, stand alone, level measurements, even if based on a monitors color temperature. I will try to find a monitor tonight that I can figure out how to set the color temp and gamma on. Best to all.Ron</blockquote>

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