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New Zeiss APO Binoculars (1 Viewer)
- Thread starter william j clive
- Start date
Art Thorn said:
I agree! APO design is not that difficult using modern computer aided systems - the problems come from variables which are very difficult to control during manufacturing. A perfectly polished lens from expensive glass (ED-type) may turn out to have a non-homogenous refractive index, which easily destroys the advantages of APO design. This kind of control makes it impossible to produce bulk, which would otherwise reduce costs.
I saw an article about lens design (in the internet...hmmm) saying that in the manufacturing it is easier to use a unit specific compensating lens (to correct unhomogeneity) than to reach the tolerances required for a good (=functioning) APO design. I guess this may be the (4-lens) principle used in Zeiss "superachromats".
Ilkka
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This may be totally off base, but I believe that magnification can be calculated by dividing objective focal length by eyepiece focal length. When an object is closer, we focus by moving the eyepiece further away from the objective lens. Does that then increase the magnification (because the effective focal length of the objective is increased)? And do all manufacturers specify magnification when focussed at infinity? Like I say, maybe I'm totally off base. I should dig out an elementary physics book.
Art Thorn said:
I agree about the calculation principle, but don't the two focal lengths just stay constant during focusing - as well as their ratio. The objective produces the image inside the tube and the eyepiece acts like a magnifying glass to watch the image. This has to be at the same distance from the image.
Ilkka
I just spent a half hour looking at some thin tree branches against a bright mornig sky. Not enough light yet to see the details on the branches - just silouettes. I tried three different Nikon glasses: 8x32 SEs, 10x42 SEs and 10x32 HGs. I also tried my Televue 85 Scope (APO, air spaced doublet objective lens) with a 14mm Radian eyepiece. I was looking for two things, chromatic aberration and size of image. The results surprised me a bit. First of all I could see no difference in chromatic aberration amoung the glasses. When I thought I did, I picked up another pair and changed my mind. Back and forth many times and, in the end, no difference. The chromatic aberration was there in every case, not in the centre of the field of view, but definitely near the edges. When I pointed the Televue at the same branches chromatic aberration was non existant. So a 'true' APO objective does make a difference. The second thing I was looking for was size of image between the porro 10x glasses and the roof 10x glasses. They have slightly different fields of view at 6 degrees and 6.5 degrees, respectively. I didn't know what to expect but found what others have mentioned - the porro's magnification did seem less, even though they have a narrower field of view! Odd, and I can't think of any explanation except that the manufacturers might be rounding off to the nearest half power. Maybe they get to a point where they have everything just so, and have 9.8 power or 10.2 power and just leave it at that. I don't know. What other explanation is there???
Blincodave
Well-known member
As a matter of interest Art, just how good are the Nikon 10x42 SEs?
They are the glasses I pick up first almost always. I take the 8x32 when I am going into dense bush where having the widest field of view is critical in finding the fast moving warblers, for example. But for average viewing the 10x42 are as light as the 8x32 HG and are brighter at dawn and dusk. I also like the grip- my fingers don't run into each other. The focus is slower than the HGs and that is a matter of individual taste. My wife likes the faster focus; I find advantages in both. But in terms of the view - contrast, resolution, aberration - I'd say the 10x42 SEs are the best of the three. And I prefer the 10 power, not finding shake an issue.
william j clive
Well-known member
Last Saturday spent a fruitless day on Anglesey trying to see a Little Bunting that refused to show all day, then reappeared on Sunday and is still showing today. Lets hope it is still around next Saturday.
After several hours of searching got bored, and compared my 8x32 SE with a Leica 8x42 roof. The image of a bird was significantly smaller in the Nikon compared to my friend's Leica. However, this phenomenon was known to me, the big surprise came when I got out my Swaro 8.5x42 EL. Both my friend and I, after careful and prolonged comparison felt that if the Leica was a true 8x, then the Swaro was 9x or more.
At the next opportunity I would like to compare the 8.5x Swaro with a 10x roof and if the findings are in any way significant I will post the result on this board.
Clive (Super Anorak Man)
After several hours of searching got bored, and compared my 8x32 SE with a Leica 8x42 roof. The image of a bird was significantly smaller in the Nikon compared to my friend's Leica. However, this phenomenon was known to me, the big surprise came when I got out my Swaro 8.5x42 EL. Both my friend and I, after careful and prolonged comparison felt that if the Leica was a true 8x, then the Swaro was 9x or more.
At the next opportunity I would like to compare the 8.5x Swaro with a 10x roof and if the findings are in any way significant I will post the result on this board.
Clive (Super Anorak Man)
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scampo said:
Steve: It is the Nikon 8x30 EII that costs ~£280 at Ace Optics. The Nikon 8x32 SE costs ~£440. See the BVD web site for a review. The owner of Ace Optics - at least I think he is the owner - uses the 8x30 EII so read into that what you will. I bought my 8x32 SE used but as new in a private sale. Hard to find, but often well priced.
Hello Clive. I will be very interested in what you find. I have no access to other glasses at this time of year. No one is out there bird watching (too @#$ cold) and the local shops do not carry high end binocs at all. As I noted, my Nikon roofs certainly have a larger image than my Nikon porros, but I don't know about other roofs.william j clive said:Last Saturday spent a fruitless day on Anglesey trying to see a Little Bunting that refused to show all day, then reappeared on Sunday and is still showing today. Lets hope it is still around next Saturday.
After several hours of searching got bored, and compared my 8x32 SE with a Leica 8x42 roof. The image of a bird was significantly smaller in the Nikon compared to my friend's Leica. However, this phenomenon was known to me, the big surprise came when I got out my Swaro 8.5x42 EL. Both my friend and I, after careful and prolonged comparison felt that if the Leica was a true 8x, then the Swaro was 9x or more.
At the next opportunity I would like to compare the 8.5x Swaro with a 10x roof and if the findings are in any way significant I will post the result on this board.
Clive (Super Anorak Man)
I'm not sure what you mean by 'low' Marcus, but I find this thread interesting too. This optics design can't be downright simple or there would be more than a half dozen top flight maufacturers out there - everyone would be producing great glasses and scopes. What I found MOST interesting in all of the reading I have done is that Al Nagler, from TeleVue, said he can only produce limited quantities of his biggest scopes because he can't get good, uniform, exotic glass to make his large objectives. Someone else in one of these threads said essentially the same thing - lack of uniform dispersion of the added components in glass is the limiting factor in producing great optics. Very interesting!! :h?:marcus said:
scampo
Steve Campsall
It is interesting - I had to return a medium priced scope because it had micro-bubbles in the field of view (probably eyepiece) - then I found all of the shop's remaining stock of that scope (three more) had similar or other marks on their inner surfaces.
This makes me wonder if the pricing of these top scopes from Kowa, Nikon, Swaro, Zeiss and Leica, etc. isn't high merely because of profitability but - just maybe - because the particular ED or APO type glass they use is genuinely difficult, and therefore expensive, to produce. It would be interesting to know the answer, as we generally feel that we are being somewhat taken for a ride at the prices we have to pay.
This makes me wonder if the pricing of these top scopes from Kowa, Nikon, Swaro, Zeiss and Leica, etc. isn't high merely because of profitability but - just maybe - because the particular ED or APO type glass they use is genuinely difficult, and therefore expensive, to produce. It would be interesting to know the answer, as we generally feel that we are being somewhat taken for a ride at the prices we have to pay.
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Sure opens up a whole world of questions, doesn't it? Every manufacturing process operates within tolerances. For a manufacturer to maintain a good reputation, he (they) can't afford to have wide variability in their product. So maybe high cost is also partly due to high rejection of off-tolerance product. And maybe one can find a good scope at a lower price by having a large number to sift through - finding the one that came through the line with no flaws. But, as Steve points out with the four scopes he looked at, you have to have a large number to sift through. Makes you think twice about mail-order.
