Focal length probably plays a factor in the
perception of depth of field with binoculars as it does with camera lenses. Longer focal lengths produce better
depth perception even when the actual DoF is the same.
The ZR 7x36 ED2 has a longer FL than the 8x32 LX (stand them next to each other to see the dramatic difference).
In addition, the fast focuser of the LX produces shallow
depth of focus. Turn it just a smidge and images in back or in front of your target become a bit blurry. This gives the perception of shallower depth of field, particularly if your focus accommodation “ain’t what it used to be”.
Field curvature also plays a role in the depth perception. When the edges are slightly out of focus and the centerfield is sharp it gives a greater perception of depth. The ZR has field curvature, the LX has very little.
Stereopsis also plays a role in depth perception in binoculars. The ZR’s 36mm objectives are slightly wider than the LX’s 32mm objectives, which might contribute slightly to a better 3-D effect.
So there are probably multiple factors involved, but I think the most significant in the depth perception between the ZR 7x36 vs. Nikon 8x32 LX are the differences in focal length and depth of focus.
Here’s a Webpage titled “Understanding DOF in Photography". Although there are different variables in photography than binoculars, there is an overlap.
Here’s an excerpt that seems most relevant:
“Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below (see chart and also photos near top of page).
This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness.”
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
Addendum: As far as the stiffness of the focuser in cold weather, Steve (mooreorless) compared the ZR 7x36 ED2, Nikon 8x32 LX, and Swaro 8x30 SLC on another thread. At 5* F, the SLC was the only focuser still turning smoothly.
I've used the 8x32 LX many times in temps below freezing without any stiffness (the focuser, not me, that's a different story), but apparently a half hour in 5* F is its limit.
Although it was cold today (25* F high, not as cold as it had been, 8* F low last night), it was sunny, so I finally had a chance to use the ZRs for the first time this week.
The focuser was quite stiff after acclimating to the cold temps. Backyard birding was pointless except if I kept focused at the tube feeder. Flighty birds like chickadees and titmice were long gone before I had the chance to turn the focuser with a pair of vice grip pliers.
So I went to the park and observed at longer distances where the depth of field is greater. Much nicer. At longer distances, I didn't have to use the focuser much so I held the bins near the end of the barrels, which provided a very stable view.
Not much wildlife outside... a few crows chasing a hawk, a guy walking his dog, but the horses were out. Two mares and a foal were covered with jackets. The male did not have on a jacket (but it looked like he had Eskimo boots on since he was a a huge, hairy, very tall Clydesdale). He kept a close eye on me as I walked around the corral. Steam shot from his nostrils like smoke from a locomotive engine. If you rode this behemoth and he threw you, you'd know how Evil Knievel felt.
