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