| Stud Duck wrote:|
Will you please explain the "rolling ball" effect to me; what causes it, how is it prevented by using HD glass and what are its perceived effects to the user IF one suffers from it. Also, are the Swaros the only make of binos that suffer/cause this effect?
I obviously don't suffer from it, I have an older set of Swaros and haven't noticed anything odd when panning across scenery.
I thought I didn't suffer from it either untill I looked through a $2,400 Swarovision
. Boy was I not prepared for that!
Rolling ball happens when you are panning a binocular across the scenery. Magnification magnifies movement as well as everything else. What happens with rolling ball is that the magnification of the binocular magnifies the movement of the image on one side as new scenery comes into view as well as magnifies the movement on the other side as scenery leaves the field of view. It makes the edges of the view look like the image is rolling along like a ball, hence the name. It can even look like the edges are rolling into the center of the field too. Sometimes it is dramatic, and other times pretty subtle, even unnoticeable. The overall effect is somewhat like motion sickness.
Manufacturers typically design in some pincushion distortion (the fuzziness usually seen at the edge of the view everybody complains about) to prevent the rolling ball effect. The distortion cloaks the movement magnification at the edge and, for most people anyway, cancels out rolling ball. What Swarovski evidently decided to do was to finally offer a truly flat field that really is sharp to the edges, as many people were crying long and loud for. Some people have enough distortion built into their own eyesight to counter the rolling ball. Those folks absolutely love their Swarovision. For those like me, who it bothers, they upgraded the SLC series from the SLCneu to the SLC-HD. This has some pincushion built in, so the rolling ball is much less of an issue with the SLC-HD. It is not as perfectly flat and edge sharp as the Swarovision, but sometimes even spending as much money as you should logically have to spend on a binocular, you still have to accept a compromise or two.
The field flattener effect on the Swarovision is largely accomplished with a more expensive and complicated eye piece design. This is not needed in the SLC-HD philosophy, so the eye pieces are less complicated and less expensive, and the SLC-HD is less money than the Swarovision.
HD or ED glass really has nothing to do with rolling ball. Those types of glass are useful in eye pieces for field flattteners and in objectives to improve contrast and help control color fringing in the image. Lots of people are really bothered by this, some so much so that they need very expensive glass that excells at controlling color fringing. That is what the glass types do.
Your older Swaros have some pincushion, which is maybe why you don't see it there. This is kind of why I was cautioning you in another post not to spend a whole lot of time worrying about looking for edge sharpness. Edge distortion is not necessarily a flaw, it is designed in for a purpose. Yes, it can be overdone. Don't spend more than a minute to evaluate it, then forget about it. People can inadvertently sensitize themselves to lots of various flaws. Sometimes your eyes will eventually accomodate the rolling ball effect, and sometimes not.
Swarovision is not the only binocular to show this. Another one you see it mentioned is the Nikon LX series of glass (mentioned by Frank above), also designed with sharp edges. A lot of whether or not people will be bothered by certain effects can only be answered by the eye of whoever is looking through the binocular. This is why there can never be a perfect binocular for everybody and there can never be a definite, absolute ranking of all binoculars from best to worst.
Edited by Klamath - December/07/2011 at 23:12