tenex
reality-based
Here is the original (2005) post reporting this alleged phenomenon:
So two possibilities exist. First, it's simply a confusion or mistake on his part, which he never followed up with proper investigation. (I'll put my money there, as I suggested above.) Second, it's a real phenomenon which many more careful observers on BF might have been expected to report over the years (as they have not), and a plausible explanation for it would have to exist. You come a bit closer to enunciating one here:
I repost this in a form that allows following the link, to learn that this person posted a few dozen messages on BF 15 years ago that cannot be said to be of a technical nature, and gave no indication here of any particular care in measuring or verifying this purported difference in perceived DOF. No one seems to have found the report interesting enough to pursue or inquire further into at the time, yet here we are now, asking how to explain it.I have two pair of Leica Trinovid 8x42 BA. Externally they look identical. Comparing them, I noticed that they did not produce identical images. One pair has a bluish tint to the coatings, and the other has an amber tint. The blue pair produces a brighter, whiter image that requires pinpoint focusing. The amber pair has a darker image, but seems to allow for less focusing at similar ranges. What I mean by focusing, is that with the amber pair I can shift my view to a different object at a different distance, and it is not as badly out of focus as it would be with the blue pair.
So two possibilities exist. First, it's simply a confusion or mistake on his part, which he never followed up with proper investigation. (I'll put my money there, as I suggested above.) Second, it's a real phenomenon which many more careful observers on BF might have been expected to report over the years (as they have not), and a plausible explanation for it would have to exist. You come a bit closer to enunciating one here:
This is still curiously vague, but I might take you to be suggesting that shorter wavelength light, having greater refraction, would present a greater challenge in focusing, and therefore the "bluer" Trinovid could seem to have less DOF? (What would that mean for Swarovskis vs Leicas today?) But how much bluer is it really? You're inviting us to envision the transmission curve for Trinovid BA 42, which Allbinos didn't measure back then but probably ranged between 80~90% across the visible spectrum, and imagine that tiny variations in overall color within that narrow range due to coating differences can have easily perceptible effects on DOF which however have only been noticed by the incomparable "bodromarsh" in the history of this forum. That is what strikes me as absurd, although I'm prepared to review any evidence you might have to the contrary but are for some reason withholding.The eye, using a simple lens, suffers from longitudinal chromatic aberration, so its ability to accommodate for different distances in a view can depend on the distribution of colors in the light involved.