double vision? (1 Viewer)

Hi,
Not sure if anyone can advise me...
I recently had a pair of Vortex Viper 10x42s on trial, and was a bit surprised on using them to find that I didn't seem to be able to just see one image - there was a sort of a black line down the middle or slight overlapping image, almost like the images from both barrels were visible at once. I had adjusted the eyecups as per instructions, the diopter, and what the instructions called the "interpupillary distance" (which basically for me meant having the barrels as close together as they could go), but still got this effect. Sometimes my eyes seemed to suddenly "adjust" and I saw one image, but my eyes did feel strained after using the binoculars. So, my question - is this because these binoculars don't "fit" me in terms of not being able to get the interpupillary distance close enough, or does it sound like these particular pair of binoculars are not right?

It sounds like the interpupillary distance adjustment of the Vortex doesn't get narrow enough for your eyes. Have you ever had this issue using other binoculars? Are your eyes close set?

The IP distance is an often published figure and you can use the Vortex as your guide knowing you need a bino that goes narrower. You can also measure the IPD with a scale by measuring the center to center spacing of the light circles coming out of the eyepieces held at say, arms length.

You can use the above method to measure your own pupil spacing, with the help of a friend.

Good luck.

Your IPD narrows as you focus closer and many people just accept a bit of overlap at close distances. But if you had overlap at longer distances then, yes, the IPD was too great for you. If it's any consolation, a lot of women have the same trouble. The Viper's minimum IPD, at 59mm, isn't particularly helpful, but not particularly unusual either.

Another way to measure your IPD is to set a pair of bins at the right distance, with no overlap, and then measure from the inside edge of one ocular to the outside edge of the other. Some bins even have the distances marked on them.

Here are some threads that have dealt with the topic (there may be others):

praise for Zeiss FL minimum interpupillary design efforts
Best for short interpupillary distance
7x42 roofs < $1k, 6x-7x bins for kids, IPD

Michael

Hi ClaireH;

I have attached a table found while I was doing some experimenting with average IPD setting errors.

You might find your age and set binos to that average figure, use MacGee’s method of setting. Start by moving a mm or two in one direction or the other until the image looks right to you. 70% of the people tested are within 3mm of the average shown so with a 4 mm exit pupil, you may be starting close unless you have a real unusual face shape. You will get the dark center line when either to close together or to far apart.

Have a good day.
Ron
http://web.inonu.edu.tr/~tipdergi/include/getdoc.php?id=831&article=432&mode=pdf

I don't think the suggestion to set the IPD to one's age group average is a very useful approach given that a 6 mm bracket only captures 70% of the population. I know three women who are over 30 (and who are average to tall in height--they aren't miniature people) and who have an IPD under 56 mm (they are 55, 54, 52) which is the minimum setting on most roof prisms. They can't use 2/3 and full-sized roof prism binos because they cannot set the IPD close enough, cannot get proper image overlap, and thus get the black area that Claire described. Having the barrels too close together does not produce such an effect, so I think it safe to conclude that the substandard 59 mm minimum IPD design of the Vortex Viper is too wide for you Claire.

If you are lucky, your IPD is at least 56 mm (though it is best to have room to spare for comfortable overlap at close focus distances). If so, there are many binos that adjust down to 56 mm, but I suspect from your description that you are something under 56. The best way to check your IPD is at an eyeglasses shop or optometrist. It is easy to measure it yourself by using a double-hinged pocket roofs binocular. Such binoculars allow a wide range of adjustment, yet because of their small size (small exit pupils) to get a good image you must set the IPD very accurately. Once you have them set to your eyes so that you can see comfortably, you can measure the distance from center to center of the oculars (or more easily, from the outside edge of one to the inside edge of the other) in order to measure your IPD.

If your IPD is at least 54 mm and you are interested in a roof prism bino in the same price range as the viper, have a look at the Zeiss 8x30 Conquest. It would be a better choice than most other binos, even if your IPD is 56 mm, because your IPD is less at close distances. Alternatively, the Zeiss 8 and 10x32 FL are much more expensive but get down to 52 mm. The Leupold Yosemite 6 or 8x30 is a relatively cheap but nice porro that gets down to 50 mm.

--AP

Hi Alexis;

You may well be correct. I was suggesting a starting point to work from if Claire does not know her IPD. I have only measured 5 women and they happened to fit the average with the minimum being 60 mm FIPD (pupilometer).

Have a good day.
Ron

Ask the shop to check the collimation .easy.

This isn't an eye relief problem is it?

Have you you solved the problem yet, the shop should be able to advise on something like this.

Henry B said:

Have you you solved the problem yet, the shop should be able to advise on something like this.

Click to expand...

To what "shop" are you referring here? If you mean the store where the binocular was purchased, I'm not sure that is necessarily a very good place to start. I have often been truly astounded at the relative ignorance of the people behind the counter at most stores I have ever frequented. At least, I hope it is ignorance because the only other choice would be blatant dishonesty.

In a couple cases the information I overheard being told to another customer was so completely wrong that I couldn't stop myself and I interrupted and corrected the salesman. In both cases the customers were very thankful to receive proper information and if looks could kill, the salesmen would now be in prison for murder. o

lucznik said:

To what "shop" are you referring here? If you mean the store where the binocular was purchased, I'm not sure that is necessarily a very good place to start. I have often been truly astounded at the relative ignorance of the people behind the counter at most stores I have ever frequented. At least, I hope it is ignorance because the only other choice would be blatant dishonesty.

In a couple cases the information I overheard being told to another customer was so completely wrong that I couldn't stop myself and I interrupted and corrected the salesman. In both cases the customers were very thankful to receive proper information and if looks could kill, the salesmen would now be in prison for murder. o

Click to expand...

Quite agree, the level of product knowledge is abysmal in some places, thats probably why she asked on here, pity she hasn,t returned