Eye focus shifting point of impact?

I’ve never had this happen before, so I wanted to share it with my shooter buddies and see if anyone had any insight. Shooting my GP100 Match Champion, if I close one eye bullseye style and shoot with a hard front sight focus, the gun’s point of impact is ~4 inches to the right at 25 yards, with the front sight centered. No problem, I could just drift the front sight over. However, here’s the weird thing. If I open both eyes and don’t use as hard a front sight focus, but just kind of center the fiber in the rear notch, the point of impact shifts back to dead center, with about 0.50-1.00 inch increase in group size.

I’ve never had this happen before, and I’m kind of wondering what caused it. My current theory is that because I’m not as hard focused on the front sight, there’s a slight amount of blur on the fiber that’s “filling” in the gaps. So a centered green blob puts hits on paper but opens up my groups a bit.

Thoughts?

21 thoughts on “Eye focus shifting point of impact?”

  1. Well, after reading this I went out back and tried both ways to see what would happen.

    I’ll have to admit I’m stumped because, my point of impact didn’t change whether bullseye style or both eyes.

  2. I’d check whether the “hard focus” process is doing something to your grip or trigger pull that you aren’t noticing due to the over-focus on “focus.” Some sort of sympathetic hand tightening maybe?

  3. I’d try the same thing with a different gun first.

    My other idea is that your eyes are aging and it’s changing where your stereoscopic vision converges.

    1. After this, I took a serious of eye tests online. The conclusion: I have astigmatism in my left eye, and I need to see an optometrist.

      1. Caleb – I have dealt with astigmatism AND cross-dominance for quite some time now. Just went for a new exam, prescription, and glasses. Wow! The difference…. Well worth your time and the trip.

  4. Sorry this is not an answer, but possibly a road for some additional interesting experimentation. I ran across a very informative article awhile back on Pistol-Training.com by Gabriel “OrigamiAK” White regarding vision and shooting with both eyes open. Here is a link if you want to read the whole thing:
    http://pistol-training.com/articles/vision

    I have been working with the exercises and I would be interested to see if your results change when you keep the eyes convergence on the target and change up your focus so that you have a clear front sight picture. You will have to read the article for the full explanation, but you will be seeing a single target (blurry) and two front sights (clear). You will want to disregard the outer of the two images, and the rear sights will look as they do when you are closing one eye. With a clear sight picture again, but both eyes open, I am curious what this will do to your point of impact and group sizes.

    It is different for everyone, but I found that I picked these exercises up fairly quickly. I started by using my thumb and a fixed point on the wall (light switch), and quickly moved up to using the sights when I was able to duplicate the exercises he described reliably and quickly. Slight warning though… if you are like me, you will get caught up in the exercises (it was kind of fun for me… I know… I am a little weird) and you will find your eyes can get pretty tired afterwards. I lost track of time and I have to say, I have never had my eyes tired from a “workout” before that (keeping convergence and changing focus repeatedly), but that was definitely a new feeling 🙂

    I hope this makes sense. If you try it out, I would be interested to hear the results and what it does to your shot placement.

  5. I have prescription shooting glasses because the target was getting blurry, that was 4 years ago. Now I have prescription shooting glasses with progressive focal point lenses, so I can see clearly close up too . . . . .

  6. I have just recently received glasses to correct a funky astigmatism. I had never had an eye exam before, but noticed that I had started to squint to see things more clearly. I first noticed it last year, and it seemed to get worse kind of quickly(33 years old).
    My wild ass guess is that you may have a bit of astigmatism in your right eye as well. When you close your left eye, you probably squint your right eye in sympathetic movement. This probably changes the way you perceive the sights and shifts poi.

  7. Ok I could be wrong but part of that sounds kinda like the old triangulation ranging problem (put your arm out with the thumb up, close one eye and note where you see the thumb, repeat with the other eye… It works with compasses, a good map and any distant object too). Also I can sometimes make this work with a soft focus on an object and both eyes open… Not sure if any of this helps, good luck.

  8. I believe its the which eye is Dominant thing. Most people have either Right or Left eye dominance. Some people are 20/200 I think they call it where they have eagle eye equals. Take the Dominate Eye Test to see. Fighter Aces and Snap shooters, exhibition shooters have this and a wider field of view than most everyone else. Ted Williams the Ball Player had that and all of the other too.

  9. A suggestion – start with an ophthalmologist (a medical doctor who specializes in the eye) and get a full eye exam, during which they’ll perform a refraction to determine what the prescription for corrective lenses should be. There may be other issues at play, some of which could be subtle. I’d suspect that if you have identifiable astigmatism in one eye there’s a good chance you have it in both.

    When you get your corrective lenses, discuss how you want them made with the optician. Bausch and Lomb used to make a yellow glass called Kalichrome specifically for shooters, don’t know if it’s still available. Some years back I had a set of Kalichrome lens glasses for which I had three right lenses, two of which with diopter differences from the “standard” prescription the ophthalmologist called for, and with different astigmatism centers (the left lens was my standard prescription for that eye). The diopter change in the two extra right lenses brought the front sights into sharp focus; the “pistol lens” had the astigmatism center exactly in the center of the lens, where a lensmaker would normally put it, but the “rifle lens” had the astigmatism center high and left. That point was determined by bringing a rifle to the optician’s shop and him marking a lens in my shooting glasses frames for the point on the lens I was looking through while in the prone and sitting shooting positions. It made a difference in my shooting.

    FYI, Kalichrome, if it’s still available – AFAIK – in glass only, so they’ll be heavy.

    If you spend a lot of time in front of a computer screen you might also consider “computer glasses” – they have a diopter change to both lenses based on the distance between the monitor and your face in a normal sitting position, and make long hours on the computer much more pleasant because your eyes aren’t working as hard to stay in focus at that distance.

    1. I just recently got Computer glasses from my eye doctor. Cost $400.00 D’s. They have anti-glare coated lenses like scopes and binoculars and are highly scratch resistant. I had B & L shooting glasses long time ago that changed yellow for haze, grey for snow and brown for sun. They were glass lenses. Still have them but not able to have the frames adjusted because of stretched metal.Could probley transfer lenses to a new frame but would require another set. Bought mine a long way back in shopping mall for $89.00 D’s. Pocket change today. A digital eye test is best but cost about $40.00 extra beyond regular eye test. Does other things too like testing for cancer,diabetes, lens degradation and tunnel vision. Best $40.00 you could ever spend. What is eyesite worth?. Still like tempered glass lenses better than plastic , fewer scratches. A line in the movie The Graduate when discussing his Career; the guy said “Plastics”. Little did we know then.

  10. Have the same problem. Learned shooting in the army with both eyes open. When I turned to sport shooting and did a lot of accuracy training, I realised that my groups tighten when I close my non dominant eye. And I Have a POI shift (but don´t remember at the moment in which direction…its a long time ago that I shoot with both eyes completely open)

    1. I was born shooting with both eyes open I believe, (Lucky Me). I tried squinting but after a little while my eye/eyes (Eye Lid) starts to twitch like Dirty Harry when he gets pissed off. Both eyes open also doubles your field of view; good for shots @ running game and snap shooting. You don’t lose depth perception either. The main failure of WW 2 fighter pilots who lost it and were retired from air combat–to a desk job I’ll bet.

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