Advice on the ipd of binoculars

[Rocket dog]

Hello Everyone,
                           I wonder if I could ask a few questions and have some advice please about binoculars, particularly the ipd of them,
I have a large ipd, (76 mm) which is proving a problem for choosing a pair of porro binoculars, as many sets I’ve had a look at seem to reach a maximum range of about 70 to 74mm

I would really like a 20 x 80 (or 25 x 100) set with an ipd which covers 76mm,  I have emailed a few suppliers and one has replied back, apparently  the Omegon Nightstar 20 x 80 has a ipd of 77 mm could anyone on the forums confirm this before ordering them, only to be disappointed?

 Also I’ve been managed to look though a Celestron pair of 20 x 80 and honestly I found them uncomfortable to use and unless I was using them incorrectly I had two 'dark shadows' running down the centre of the image, would this be a result of the ipd being too small for me or maybe something else?

And as always,  if anyone in the forums could offer some suggestions or advice of make and models to look at, what to avoid etc, it would be appreciated.  

Thank you.  

 

[Peter Drew]

It's most important that your IPD matches the exit pupils of the binocular or you will get, what you have found, dark patches in the field of view.  An IPD of 76mm is unusual but I would have thought that a suitable binocular exists.  If the exit pupils of the binocular are greater than your eye's pupils then there can be a bit of compromise, unfortunately larger and higher magnification models tend to have small exit pupils.  There are mechanical stops on the hinge of a binocular that determine the degree to which the IPD can be extended, maybe this can be modified, as a tinkerer this wouldn't stop me if all else failed!     🙂

[Mr H in Yorkshire]

8 hours ago, Peter Drew said:

as a tinkerer this wouldn't stop me if all else failed!     🙂

I am similarly inclined (and as a result have done for a number of things by misadventure, live and learn) but the problem might be that at maximum hinge width as supplied, the two optic's axes and the hinge axis are already on a straight line. The old Apogee binos I use with my portable binochair certainly have room to spare, so some judicious filing would work. It will clearly depend on the construction detail of the binocular.

[Rocket dog]

On 17/12/2023 at 12:10, Peter Drew said:

It's most important that your IPD matches the exit pupils of the binocular or you will get, what you have found, dark patches in the field of view.  An IPD of 76mm is unusual but I would have thought that a suitable binocular exists.  If the exit pupils of the binocular are greater than your eye's pupils then there can be a bit of compromise, unfortunately larger and higher magnification models tend to have small exit pupils.  There are mechanical stops on the hinge of a binocular that determine the degree to which the IPD can be extended, maybe this can be modified, as a tinkerer this wouldn't stop me if all else failed!     🙂

Thank you for your reply, if I may ask, I have been reading some reviews that certain binocular ipd go up to 74mm are these numbers accurate or do some manufacturers make the ipd something like 77mm, but just to be careful in their description they say 73mm. (if that make's sense)

And can anyone give their best dos and don’ts with regards to binoculars please

Thank you

 

 

[Peter Drew]

Binoculars are a precision instrument at a reasonable price point so I think it unlikely that there would be that level of inaccuracy. Most binocular vendors would accept a return if a model supplied did not reach the IPD specified by the purchaser.  Difficult to advise do's and don'ts as binoculars are such a personal thing, common pointers are weight, magnification limit for hand holding and, as in your case, IPD range.  Porro prism binoculars tend to be better value price for price than roof models.  The only real test is to try and see for yourself.     🙂 

Edited December 22, 2023 by Peter Drew

[Rocket dog]

On 22/12/2023 at 19:30, Peter Drew said:

Binoculars are a precision instrument at a reasonable price point so I think it unlikely that there would be that level of inaccuracy. Most binocular vendors would accept a return if a model supplied did not reach the IPD specified by the purchaser.  Difficult to advise do's and don'ts as binoculars are such a personal thing, common pointers are weight, magnification limit for hand holding and, as in your case, IPD range.  Porro prism binoculars tend to be better value price for price than roof models.  The only real test is to try and see for yourself.     🙂 

Thank you for the help and advice Peter.