This article was written a few years ago and needs an update at this point. In the last few years, I’ve worked with and discussed the subject of vision with many shooters and it has led to a lot of insight. Everything in the original article is true, but the perspective I wrote from (a right handed and right eye dominant shooter who uses iron sights with both eyes open and has unlinked convergence and accommodation) is narrow and fails to directly apply to a great many other shooters.
See what you need to see is still the truest answer. Different people learn to work with different visual details and different levels of visual certainty all quite successfully.
Here’s a little shorthand that can help someone cut through the heavy technical orientation of the original article:
If you have a hard time with a doubled image (particularly the target) when keeping both eyes open and using iron sights, you probably have a strong natural linkage between your convergence and accommodation (see original article for details.) You are probably a good candidate to explore and develop two main aiming methods – target focused shooting with both eyes open on easier shots, and closing or squinting your nondominant eye for harder shots that require the detail allowed by sight focusing (sharp and clear front sight.) Closing/squinting the nondominant eye will eliminate the problem with the doubled image. Ideally, closing/squinting the nondominant eye should be done after the decision to fire has been made and as the gun is being brought into alignment with the target, whether that is from the holster, a ready position, or a previous target.
If you have a hard time getting the front sight sharp and clear enough to see the necessary detail for difficult shots, you are a good candidate to explore and develop target-focused shooting with the sights blurry. High visibility sights that are more visible even when blurry will usually help a lot with this, whether they have a fiber optic in the front only, in the front and rear, or are any of the high visibility night sights that are available, with bright orange/yellow/green markings on the face of the front sight.
To borrow a profoundly-correct statement from five-time USPSA National Production Champion Ben Stoeger, don’t underestimate how fast you can learn to be with sight-focused shooting, and don’t underestimate how accurate you can learn to be with target-focused shooting.
This describes how vision works for me personally. I am terribly nearsighted and wear normal, single-vision eyeglasses. I do not have any formal training in the study of the eyes or vision. I have simply sought to understand visual processes to better practice and enjoy shooting. Some of what I describe here may not apply to a person with vision issues that I have not experienced, such as astigmatism, vision corrected with monovision prescriptions (one eye corrected to see near and one to see far), etc. None of the following is new information. This is simply how I organize and execute these visual processes in my own shooting. I am right handed and right eye dominant, and I shoot an iron-sighted pistol with both eyes open.
Preliminary Definitions and Discussion
There is a lot of confusion in the shooting world as a result of imprecise language and misapplication of terms. ‘Look at’ and ‘focus on’ (the front sight) are often used interchangeably, but that is not a precise way to refer to the relevant visual processes.
There are two separate visual processes we are dealing with in this discussion: the spot your eyes are pointed at, and the distance that is in sharp and clear visual focus.
The spot your eyes are pointed at is called ‘convergence‘. The depth of visual focus is called ‘accommodation‘. I will try to stick with those terms from here forward.
The following illustration shows convergence only. Accommodation is not addressed yet.
In the left illustration, the shooter (who, like me, is right handed, right eye dominant, and shoots with both eyes open), directs his convergence the way I do – both eyes are converged on the target spot. In the right illustration, the shooter directs his convergence in what I guardedly call ‘the wrong way.’ His eyes are converged on the front sight.
An essential aspect of convergence is that there is only a single image of the spot/area being converged on. All other objects/depths will have a double image. The double image can be very hard to notice when the brain is primarily or exclusively paying attention to what your eyes are converged on, but the double image is there. This is simply the nature of binocular vision.
In the left illustration, the shooter’s eyes are converged on the target spot. He sees one target. He sees two guns. The inner (left) gun is the image coming from his dominant right eye. That’s the image he needs to align with the target. The outer (right) gun is the image coming from his nondominant left eye. That image needs to be ignored when aligning the gun with the target.
In the right illustration, the shooter’s eyes are converged on the front sight. He sees one gun. He sees two targets. The right target is the image coming from his dominant right eye. That’s the target that would need to be aligned with the gun if a person shot this way. The left target is the image coming from his nondominant left eye. That image would need to be ignored if shooting this way.
Convergence of the eyes on the front sight is often the culprit when a person finds visual confusion in target transitions and they find that the targets double. When I try to run my vision this way, I find additional difficulty in seeing the front sight through the rear sight notch. Because of the tight double image of the rear sight when convergence is on the very near front sight, it makes the rear notch image slightly doubled and it makes it difficult for me to perceive the light bars on both sides of the front sight. This is not an issue when converged on the target spot because the angles are wide enough that the nondominant gun image is far enough off to the side that it can easily be ignored.
Closing one eye eliminates the double image, which is a valid method when there is insurmountable visual confusion in the double image (wherever that is) for a given shooter.
As a related side note, convergence is what must be manipulated to see Magic Eye 3D pictures. The two eyes have to get pointed at different parts of the picture, which allows the separated image to reassemble and the 3D image ‘appears’.
Convergence and accommodation are naturally linked. They both move together in normal, non-shooting activities. There is normally no reason to separate convergence from accommodation. Whatever you look at (convergence) is normally what you want to see sharp and clear (accommodation.)
In shooting with iron sights, it is very useful to be able to separate convergence from accommodation and exert control over those two processes separately and independent of each other. It is also useful to be able to shift accommodation back to front sight depth, but before the front sight and gun get to their final shooting position at full extension.
Standard Use of Vision in Shooting
This is my execution of the standard, accepted process for vision in sight-focused shooting with iron sights:
Convergence and accommodation start out unified and on the target spot. There is one target spot and it is sharp and clear.
Once the decision to fire is made and as the gun is brought from wherever it was (holster, ready position, previous target) to its final shooting position, convergence stays on the target spot but accommodation shifts back to where the front sight is about to be. There is still one target spot but it is now blurry, because accommodation is at front sight depth. When the gun arrives in its final firing position, the front sight is immediately sharp and clear since accommodation is already at front sight depth. There are two guns since convergence is on the target spot. Use the dominant eye image (the inner of the two images) to align with the target spot. Disregard the nondominant eye image (the outer of the two images.)
The shooting commences and shots are called without moving either convergence or accommodation.
When the sharp and clear front sight lifts on the last shot on a given target, convergence and accommodation both snap to the next target spot and are again unified (one sharp and clear target spot.) As the gun is driven toward alignment with the new target spot, accommodation is pulled back to front sight depth before the front sight is there. When the gun arrives in its final shooting position, there should again be one blurry target spot and two sharp and clear guns.
This process continues until the shooting is done.
By learning to shift accommodation back to where the front sight is going to be but before it is there, we either save time by concurrently moving the gun and our accommodation, and not having to wait for the front sight to get to its final position before shifting accommodation to it, or we increase certainty by immediately seeing the most precise and certain sight picture at the earliest opportunity. If we must wait for the gun and front sight to get to their final position before shifting accommodation back to front sight depth, we either lose time by moving the gun and accommodation consecutively rather than concurrently, or we fire the first shot or shots when still target-focused and with a lesser degree of certainty. Target-focusing works on many shots. There are also many shots where the precision and certainty allowed by target-focusing are insufficient for the difficulty of the shot.
The at-will focal shift allows us to get the most precise and certain information from our sight picture at the earliest possible time.
Learning the At-Will Accommodation Shift
So now the question is, how can we unhinge accommodation from convergence and commit accommodation to our conscious control so that we can get the most certain information from our sights at the earliest possible time?
Some time ago, I read somewhere on the internet about this exercise and it worked for me. I don’t know who deserves credit for this method.
This is how I learned the at-will accommodation shift:
Pick a distant target spot or object (at least significantly further than the length of your arm) and put your vision on it. Laser focus your eyes on it. See it sharp and clear. Your convergence and accommodation will be unified at this point.
Using your thumbnail or other small object as a substitute front sight, keep your vision just like it was and with your arm fully extended bring your thumbnail into your eye-target line and align the tip of your thumbnail, as if it were a front sight, with the target spot/object. There should be one hard sharp and clear target visible, and two blurry thumbnails. Now keep that alignment and bring your focus/accommodation back to the thumbnail. There should still be one target, though the target will be blurry, and there should still be two thumbnails, but they should now be sharp and
clear. The alignment of the target spot and thumbnail are unchanged.
Keep the alignment of the target spot and thumbnail the same, but shift your accommodation out to the target and back to the thumbnail. Make one sharp and clear, then the other, and repeat many times. There may be feelings of strain in your eyes as you exercise the tiny muscles that control accommodation. Carefully notice the sensations you feel in your eye muscles.
Next, do the same thing and once you have the thumbnail sharp and clear, hold your accommodation at the distance you had your thumbnail, but then take your thumbnail away while maintaining that sensation in your eyes. Do this until you can hold that distance of accommodation and make the target remain blurry when the thumbnail is taken away.
Once you can do that, take your thumb away completely so that you only have the target spot. Make yourself feel the same sensation in your eyes as you did when your thumb was present, and pull your accommodation back to where the thumbnail used to be. Your eyes should still be converged on the target spot, and there should only be one target visible, but the target will be blurry. Work to hold your accommodation at the arms-extended distance. This is what we are trying to accomplish – separating convergence from accommodation and shifting accommodation distance without the necessity of having a physical object (the front sight) actually present. If you see the target double at this point, that means you are moving your convergence along with your accommodation. We want to shift our accommodation only.
You may find that you can do the accommodation shift without the thumbnail present, but have trouble holding it there, and that your eyes almost immediately revert to unifying convergence and accommodation and the target becomes sharp and clear again as your eyes automatically accommodate back to the target. That’s ok. You’re partway there. Put your thumbnail back in line with the target and again practice cultivating control of pulling your accommodation to the distance of your thumbnail with your arm fully extended and holding it there while you take your thumbnail away. With practice, hopefully you will be able to move your accommodation closer to you and further from you at will.
Once you can consciously control your accommodation, you can practice using your shooting vision anywhere. Look at an object and fuzz it out – that is, pull your accommodation back to front sight distance. Snap your eyes to another object, which should automatically become sharp and clear due to the natural linkage between convergence and accommodation, and pull your accommodation back to front sight distance, making the object blurry. Keep repeating.
When in a car, the windshield is about at front sight distance. Use a speck on the windshield as a substitute front sight, align it with a distant object, and move your accommodation in and out, from the speck to the distant object and back.
An interesting possibility becomes available when you can shift accommodation at will. You could use your eye muscles to maintain front sight accommodation during target transitions, but otherwise use the conventional target transition process to direct your convergence, keeping the front sight perpetually sharp and clear and the targets perpetually blurry. I don’t know whether this is a good way to transition or not, but I sometimes do this when I am having trouble being mentally disciplined enough to run my accommodation correctly. I simply don’t let myself accommodate to the target at all in a given drill/array/etc.
The Role of High and Low Visibility Sights
Spending time training with all-black sights helped me learn the at-will accommodation shift. I used to always use some kind of night sights with a ‘high visibility’ front sight – normally one with a white ring painted around the tritium on the front sight. Note that the glowing tritium in low light is not part of this discussion. I’m talking about using these sights in reasonably good lighting conditions.
The vast majority of my shooting is done on an indoor range, which isn’t the brightest – certainly not as bright as outdoors. It became apparent to me that for a very long time I shot with a target convergence and target accommodation, at least for the first shot or two in a string, until my eyes could accommodate to the front sight and get it sharp and clear, and my eyes couldn’t do that until the front sight was actually present in the eye-target line.
I was able to get away with that largely because of the high visibility aspect of the front sight. Because it was high visibility, it allowed me to shoot with a target focus on the first couple of shots but still have sufficient awareness of the position of the front sight since it was so easy to see, even when blurry.
When I tried plain black sights, I initially found the front sight quite a bit harder to see on the modestly well-lit indoor range. I found that I really had to get my accommodation shifted to the front sight or I would have very poor awareness of its precise position. The black sights forced me to be much more disciplined in accommodating to the front sight. If I let myself target focus then my shooting suffered in general, but especially so on tighter shots.
Since then, I have used black sights for training, practice, and competition, and they have forced me to be disciplined in controlling my vision if I want to shoot well. This led to the habit of shooting with a true front sight focus on nearly every shot.
Targets are frequently so big or close that the level of precision and certainty allowed by front sight accommodation is quite unnecessary. It could certainly be argued that I use sight-focused shooting much more than is really necessary. And I wouldn’t disagree with that. But I personally see tremendous value in cementing the habit of seeing the front sight sharp and clear, getting the most precise and certain information from the sight picture, and thus calling every shot as well as I am currently able. Learning to do this marks the last hugest improvement I have seen in my shooting.
I do hope this is clear and helps someone else improve as it has helped me improve. Vision and awareness are key to good shooting. Better visual control allows me better awareness of the shooting.