praise for Zeiss FL minimum interpupillary design efforts (1 Viewer)

[Alexis Powell]

Here is are the 3 messages that composed a string that was lost due to the recent Bird Forum hardware failure.
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I just noticed something very exciting in the specs for the Zeiss FL models for which Zeiss deserves praise and recognition--the full size models have 54mm, and the mid-size have 52mm minimum interpupillary distance settings! My wife has a 54mm interpupillary, so cannot comfortably use any of the top quality mid or full size roof-prism binos, as all of them (to my knowledge) have a 56mm minimum interpupillary. Given that at close focusing distances it is often helpful to reduce the interpupillary setting below what one would use at infinity, she isn't even completely comfortable with a 54mm minimum (which is itself hard to find--I know of only the Zeiss Conquest models, and the discontinued Nikon 8x40 Classic Eagle). The mid-sized Zeiss FL are, to my knowledge, the first premium roofs (other than compacts) suitable for her use. Given how long it took much of the bino industry to address the needs of eyeglasses wearers with regard to eye relief, I don't dare hope this is the beginning of an industry-wide recognition of the existence of adults with close-set eyes (who don't have much consumer clout), but I thank Zeiss for their attention to this detail!
--Alexis Powell


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Alexis,

I'm glad to hear other people appreciate low IPD's. The majority of bins I've seen, except for the "best", start at 58mm; some at 60mm. Thankfully, most high quality bins have a wider range. Zeiss has the best with a low of 54/52, the Nikon SE is 53, and most of the Swaros/Leicas/Nikons are 56 mm. The Swift's were quite accommodating, especially the 8.5/44 porro. I made a comparative list of bins some time ago, which I’ll be happy to share. IPD is one of those stats I often had trouble finding and I encourage manufacturers to list IPD ranges along with other specs.

I couldn’t agree more with your comment about lowering the IPD for close viewing. People complain about the SE porro in this regard and, unless you start with a very low IPD, the argument that a porro doesn’t work well at close range is nonsense. My IPD is 57 mm and, when I further reduce the IPD on my SE, the images I see at the 10-foot minimum are stunningly beautiful. Again, if you have no IPD adjustment left (porro or roof) I think close viewing is going to be a problem with anything but a near-perfect set of lenses.

FYI
http://www.cl.cam.ac.uk/~nad/pubs/EI5291A-05.pdf
has a nice IPD graph.

Based on the data presented, Zeiss should be commended for their generous design.

John Traynor


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The most frustrating aspect of the lack, until now with these new Zeiss models, of quality roof prism binos with minimum interpupillary settings under 56mm, is that so many of the current models could have been designed to go lower than they do. The limiting factor on many has to do with the limit imposed by the hinge, not the point at which the oculars or objectives bump against one another. It seems that the 56mm limit is specified as a matter of tradition, rather than engineering limitations or difficulties, presumably because designers think that 56mm meets everyone's needs. A number of porros are more generous (some of our favorites are the Swift Ultralite 8x42, Nikon 8x32 SE, and Nikon 8x30 EII), but my wife, although not nearly so interested in binos or birds as I am, has often been jealous of the handling properties of my roof prism units. If we go on a hike and she doesn't carry one of the porros that suit her, she will borrow the binos that I have brought along (always one of my premium roofs) for the occasional look, will remark on how well they fit in her hands, and then discover/rediscover, to her irritation, that they don't fit her eyes well.
--Alexis Powell

 

[MacGee]

I made a comparative list of bins some time ago, which I’ll be happy to share.

John, I would appreciate a copy of your list.

I find your IPD paper very interesting. Thanks for giving me the opportunity to read it.

Michael.

 

[Alexis Powell]

Michael,
If you want IPD specs, a good resource is Astronomics (Christophers). Unlike Eagle Optics, they list the IPD for every bino that they carry.
http://www.astronomics.com/main/cat...tegory_name/06M91XPQQNM69M5JAAT58EWUN2/Page/1
--AP

 

[MacGee]

Michael,
If you want IPD specs, a good resource is Astronomics (Christophers). Unlike Eagle Optics, they list the IPD for every bino that they carry.
http://www.astronomics.com/main/category.asp/catalog_name/Christophers/category_name/06M91XPQQNM69M5JAAT58EWUN2/Page/1
--AP

Thanks, Alexis, I'm aware of that site, but there are a lot of brands they don't cover, including UK brands. I've been assembling my own list through Internet searches, emails, questions on BirdForum, etc. I just thought that since John already had compiled a similar list, getting hold of a copy might save me some travail. I was also thinking it might be a good idea to have a Sticky listing all known IPDs.

Michael.

 

[Pileatus]

Thanks, Alexis, I'm aware of that site, but there are a lot of brands they don't cover, including UK brands. I've been assembling my own list through Internet searches, emails, questions on BirdForum, etc. I just thought that since John already had compiled a similar list, getting hold of a copy might save me some travail. I was also thinking it might be a good idea to have a Sticky listing all known IPDs.

Michael.

Michael,

My list covered IPD measurements for models I was considering at the time. I cannot effectively use any binocular with an IPD => 58mm and MANY binoculars start at 58mm. I own an Ultravid (56mm) and a Nikon SE 8X32 (53mm); both are very satisfying.

I wish all manufacturers and dealers would include IPD information along with other specifications.

Interesting factoid:
Collimation of the two oculars in a binocular can vary over the range of the IPD. In other words, your binocular (two telescopes) may be perfectly aligned at one IPD setting and misaligned at another.

John

 

[Pinewood]

Interesting factoid:
Collimation of the two oculars in a binocular can vary over the range of the IPD. In other words, your binocular (two telescopes) may be perfectly aligned at one IPD setting and misaligned at another.

John

John,

A binocular which is properly collimated, is good for the entire IPD range of the binocular. This can only be done with a proper collimator.

Many amateurs who try to collimate their binoculars arrive at what a certain optical tech, William Cook, calls "provisional alignment." I use a 58 or 59 mm. IPD, depending on whether I wear specs and perhaps something else with closeups, using a Porro. Every professionally collimated binocular I own works, even though I rarely specify my IPD to the technician. I have always posted my binoculars to the techs, and they come back properly collimated.

Happy bird watching,
Arthur Pinewood :hi:

 

[Pileatus]

John,

A binocular which is properly collimated, is good for the entire IPD range of the binocular. This can only be done with a proper collimator.

Many amateurs who try to collimate their binoculars arrive at what a certain optical tech, William Cook, calls "provisional alignment." I use a 58 or 59 mm. IPD, depending on whether I wear specs and perhaps something else with closeups, using a Porro. Every professionally collimated binocular I own works, even though I rarely specify my IPD to the technician. I have always posted my binoculars to the techs, and they come back properly collimated.

Happy bird watching,
Arthur Pinewood :hi:

Arthur,
I'm talking about the alignment of the two oculars based on rotation around the hinge. If that hinge is not designed, manufactured, and assembled to strict tolerances, the alignment of the two oculars, to one another, can vary over the range of the IPD. It's a mechanical problem.
John

 

[Pinewood]

Arthur,
I'm talking about the alignment of the two oculars based on rotation around the hinge.
That is my definition of proper or true collimation.
If that hinge is not designed, manufactured, and assembled to strict tolerances, the alignment of the two oculars, to one another, can vary over the range of the IPD.
CERTAINLY! With such a binocular, true collimation would be impossible to obtain over a wide range of IPD. Good design and attention to close tolerances make a good binocular
It's a mechanical problem.
Yes, but it causes optical headaches
John

John,

Any number of large binoculars for amateur astronomers have freely accessible screws for adjusting the prisms, a poorer way of collimation than using eccentric rings. The amateur astronomers always do a personal adjustment rather than a true collimation, which takes precision instruments, skill and experience.

I wrote of collimation done by a competent technician on a well made instrument, which may not be what you had in mind. Should Nikon or Leica service your binoculars, as I know you have at least two fine binoculars, I am sure that you would expect true collimation throughout the entire IPD range.

Happy bird watching,
Arthur