You from Joisey? I'm from Joisey. Aside from Joe Piscopo, people from Jersey actually do pronounce the "r" when they say the name of the Garden State.
How to Have a Jersey Accent
You are at least the second person who reported seeing RB in the 8x42 SF but not in the 8.5x SV EL, which is very strange since the SV EL has way less pincushion than the SF.
Looking at Holger's chart, the 8.5x SV EL is as about as low you can limbo with angular magnification distortion (AMD) without having at least some pincushion (click on chart below).
At first I thought the reason some people are seeing RB in the SF and not in the SV EL, as you might expect, might be due to the larger apparent field of view he SF (67.6* vs. 64.6*). Bins with AMD and larger apparent fields of view are more likely to show RB in those individuals susceptible to it. But 3*? Would that be enough to make such a critical difference? I dunno.
What I do know is that Dale Forbes, Swaro rep., recently posted, and unfortunately, I forgot to bookmark it, that someone (at Swaro?) found that the pattern of distortion is also a factor in why some people see RB, not just how well or poorly the AMD and k-value match (k-value is a term for how much pincushion your eyes naturally have, which varies from individual to individual). Holger has a home test for this on another webpage.
The SV EL has a "mustache distortion," that is, pincushion and AMD change over the field of view and at some point about 70% from center, there's an abrupt changeover, which some people experience as the "Absam Ring" (a circle of blurriness about 70% from the center). For some people this mustache pattern causes the image to start rolling, for others, it doesn't.
I haven't read what the distortion pattern looks like with the SF, but the implication in Dale's post is that it's different than the SV EL, and that some people might be more susceptible to RB with the SF (particularly the 8x42 model) due to the way Zeiss mixed the AMD and pincushion over the field of view.
First time I heard about this, but given what you reported and at least one, perhaps two others reported the same susceptibility to RB in the SF over the SV EL, obviously there's more going on than the overall distortion level of the SF, which from the chart is near the border of the "modern Globe Effect possible" and "moderate distortion (the latter suits my eyes better).
The nature of RB is such that most people who see it eventually adapt it it over minutes, hours or days. So if you like the Zeiss better, but are bothered by the RB, find a store that has more than a two-week return period (so far two weeks has been the maximum time needed to adjust to RB, though it's usually much less).
If you adjust to it, then it's unlikely that you will ever see it again with the SF or at least with the 8x42 model. You might have to go through the same adjustment period with the 10x42.
I did not adjust to the RB in the 8x42 or 10x42 Nikon HG, and I used both for at least a month. Steve (mooreorless) saw RB in the HGs, but adjusted to it in less than a minute. Only a trial over time will tell you whether or not you adjust to it.
If you don't adjust to the RB (i.e., it doesn't go away), you will probably always see it and will have to decide whether or not it's something you can live with.
Brock
