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Message: <blockquote data-quote="Surveyor" data-source="post: 1292166" data-attributes="member: 50720">Henry; I finally got my ELX ED back and set out to check the transmission. One problem, the reason I decided to try the ELX is that I did not have a 8x42 in my stock. To try to keep the comparison within reason, I decided to base the comparisons on exit pupil and to do that I would have to make stops either for the ELX or comparison bins. The needed stops were going to be: 8x32 Trinovid = 32mm8x36 Monarch= 36mm8x30 SLC = 30mm12x50 Trinovid=33.3mm7x42 Ultravid=36.75mm10x42 Leupold=33.6mm (Don did test, no stop, ELX+)8x50 Nikon Porro=42mm (Don did test, no stop, ELX+)20x80 Swaro= 32mm (ATS HD 80 w/20x-60x eye piece) The test did not get too far along though. After looking at the 8x32 Trinovid and 7x42 Ultravid, I had seen enough to form an opinion. I cannot see as close a difference as Henry can. I feel lucky if I can differentiate between 5 or 10% transmission. I expected more trouble than actually encountered with this checking process since I was looking to check a change of only 5% and the best estimate of JND generally accepted for the change in light intensity is 7.9% (Weber’s constant, see attachment). Without the stops I figured there would be about 25% difference with the 7x42 on top and around 40% differences from the 8x32 Trinovids with the ELX ahead assuming equal transmission values. The values to be contended with were: Trinovid 8x32, 550 nm 83.71% and peak 86.61 @ 679nm from professional run.Ultravid 10x42, 550 nm 86.31% and peak 90.1 @ 600nm from Leica (typical).Ultravid 8x20, 550 nm 88.28% and peak 92.7% @ 595nm from professional run.Promaster ELX, 550nm 88.72% and peak 91.77% @ 606 from my measurements. First I placed the 32mm stops on the ELX and look at a good, bright view area, sun behind me, so that I had very bright objects and deep, shadowed areas of contrast to compare. I could not tell any difference in the brightness by looking at this view at different times. Next, I stacked both binos on a tripod and pointed them at the north sky and elevated about 45 degrees. Doing this, I could see both exit pupils at the same time and in close proximity to each other. I also changed the position of the binos in the stack with the same results. The ELX showed a small, but noticeable, improvement over the 8x32 Trinovid and just guessing, the 5% seemed reasonable. Next, I had a look at the same view with both the 7x42 Ultravid and ELX. The Ultravid was undoubtedly brighter. I attached the 36.75mm stops to the Ultravid to match the exit pupil of the ELX and looked at the view again and could tell no difference between them. I then stacked them on the tripod as before, pointed at the north sky, and inspected the exit pupils, reversed the position and inspected again. I could tell no difference between them. After dark, when I went inside, I repeated the process for all three bins but this time I used a light table with enough ND filters under each bino to bring the light down to a very low level and inspected the exit pupils again, with the same results. In conclusion, I have at least convinced myself that the transmission curve is representative and the ELX is, indeed, closer to the Ultravid than the Trinovid in light transmission, at least at my vision capabilities. Best,Ron </blockquote>

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