Controls are identical across all three, as one expects (but worth noting that their great contemporary rival, Zeiss's Dialyt series, weren't uniform in the same way). Diopter is in front of the bridge, same as the 10x40 and 8x30 Dialyts. I actually prefer this setup, or the conventional diopter on the right barrel, to the more modern integrated focus wheel and diopter as used in the FL, EL and others. Diopter tension is adequate - ideally I'd have liked it stiffer, but it's OK. Focus feel is quite light (I would have preferred a little more weight/resistance), but precise.
Eyecups are now the twist up type (god I wish these were retrofittable to Dialyts) and have three set positions. They needed a little more pressure to start turning than I expected, but once familiar with their operation, everything was fine. I found I needed to twist the eyecups of all three up just a little to eliminate blackouts. At this intermediate setting I was wondering if the eyecup position would hold, as it didn't seem to take much pressure to turn them out once they got started, but - at least during the short time I was using them - I had no issues. The main stops are very solid.
Hinge tension: again I'd like to be a bit stiffer, but in use seemed fine, although you would need a longer trial to really confirm the IPD stays where it is.
Eye placement of all three I found pretty easy and undemanding, more than I'd expected as one expects such small binoculars to be a bit finicky. The 7x35 isn't as effortless in this respect as the 7x42 Dialyt, but its 5mm exit pupil is more than adequate. Eye placement of the 10x40 seems similar to the 10x40 Dialyt, which when looking at distant targets and for long periods, does need careful setting up - but is easy enough over shorter distances such as those I tried it over (I find the same with the 8x32 FL). Ease of eye placement for the 10x40 Retrovid really needs to be assessed over a longer trial of say a couple hours, and over different distances.
Focus speed is slower than most modern binoculars like the 8x32 FL, but I personally prefer a slower focus speed and would rather spin the wheel quicker than overshoot and have to recorrect. I had a pretty good chance to test how quickly I could get on a bird with the 10x40 when a feral pigeon landed on the pavement close to me when I was looking the other way at the furthest twigs I could find. Spun round to get a look at it (iridescent neck feathers would have been a good test subject for colour rendition) but must have startled it as it flapped up. It was gone in a couple seconds, but before it did, I was able to get a good lock on its white rump. It's quick enough for me.
One of the most immediately noticeable things about all three Retrovids is how extremely small they are compared to most modern binoculars of comparable format. The 10x40 Retrovid looks and feels about 85%-90% smaller than the rubber armoured 10x40 Dialyt, and the 7x35 feels smaller than the 8x32 FL. They feel quite weighty for their size, which combined with the small package, I think helps in holding them steady. The Retrovids are actually so small that, having gotten accustomed to larger binoculars, they feel somewhat odd in the hand. The 7x35 in particular feels almost too small for my hands, but I could see it being a perfect fit for someone like my mother (who is 71 years old and loves everything about the 7x42 T*P Dialyt other than its weight/size). Leatherette covering helps make them very slim, but feels less friendly on ungloved hands in January than rubber.
------------------------------------
In summation... I can't say the Retrovids are the best birding binoculars I've ever used, but to be fair to them, they aren't being advertised as such. Back in the 1960s no binoculars were really designed specifically for birding, whereas now they are. The Retrovids are in a somewhat different corner of the market where users want/need compactness and handiness more than ultimate optical performance or weatherproofing. As mentioned earlier, they feel a bit odd at first as they are so small in the hand, but once you get used to it they are wonderfully compact and beautifully pointable. They feel and handle (focus feel, eyecups etc) like a well made product, although only time will tell if they retain that quality feel for as long as the original Leitzes. I must confess I love how they look. They don't, at least to my eyes, look old fashioned in the way that something like a Binuxit does - although I love how the latter looks, too. The downside of that timeless classic styling is you would need to be more careful with these than something rubber armoured. Quite a few of the old Leitzes show wear at the objective ends.
Optically, although I'm not familiar with the whole range of modern 7x, 8x and 10x available today, they strike me as being pretty decent. The 7x35 gives the impression of being like a downsized 7x42 Dialyt, and the 10x40 I'd have to rate as a little better optically than my 10x40 - if I were offered an exchange between the two, I almost certainly would - and definitely (as only to be expected, mind you...) better than the old Leitz 10x40 I tried at Birdfair. They are probably maybe only a tad less good than the Meopta/Conquest HD/Monarch HG class, whose optical performance, objectively, is extremely good. So there.
A lot of commentators here have said that if classic binoculars were made with modern coatings they'd buy them. Now that someone has, it'll be interesting to see if any do. I can't say I would, not for myself anyway, but I'm a cheapskate who has never bought a new pair of binoculars. If all binocular buyers were like me, we'd probably still be using P model Dialyts (or worse), and amazing creations like the SV and SF would exist only in the fantasies of folks like Chosun.
I'm hoping that all the negativity on Birdforum - lack of Uppendahl prisms, not having retained the original optical train etc - really, really hurts secondhand values. I've always thought the leatherette version of my 10x40 looked great, but P models are very hard to find, and the 10x40 Retrovid offers that along with, in all likelihood, more neutral colour rendition. I'm not sure whether to ask my mother to try the 7x35 as I'm pretty certain she would like them...probably a little too much!
