Sight picture?

[old sparky]

I went to a indoor shoot last week. I didn’t shoot as well as I do at home. I just figured extra noise and movement equals less concentration. I didn’t think I could see my front sight as well as normal and figured the light is different. This week at home I see that the targets that I print on white paper are easier to see. When shooting the manilla colored targets I don’t see the gaps between the front post and rear notch added with not seeing a definite 6 o’ clock hold spot the black sight doesn’t stand out. So my question is since the manilla target with black bull is standard thats what I need to practice on. Would filing the rear sight increasing the gap let me see better? But after removing material I would be stuck. I am sure someone here has been where I am. any suggestions?

thanks, Sparky

[j-team]

You will be surprised how big you can make the rearsight without loosing accuracy. Most people have them too small because they think it makes is more accurate, but it doesn't.

Does you pistol have a removable rearsight blade? If so you can make a trial one from some black cardboard first to test the size before filing the real one! Stick it on with a bit of blutac.

[deadeyedick]

It is common practice to widen the rear sight notch allowing more light as we age. There is usually more to it and that applies in this instance.

For precision shooting the accepted rule is to have your front sight "apparently" the same width as the black on the target. This takes some experimentation as we have different length arms and different sight radius on our pistols.

Next is to determine how much we sight below the black and adjust/modify our rear sight width to equal the gap between the top of the front sight and the bottom of the black with an equal gap either side of the front sight.

Obviously there is a limit as to how much widening can take place..however it will improve the situation.

Following that I would consult an Optometrist and have a shooting lens made to give you a focal length equal to the distance from your front sight to your eye.

[ShootingSight]

This sounds like a vision problem developing, especially if you were stringing your shot groups vertically.

The relaxed eye will focus at infinity, and the eye muscle deforms the lens to bring focus in close. As we age, the lens in the eye loses flexibility, so pulling focus close gets more difficult, usually areound age 40 it starts. Eventually, you either cannot see close and need reading glasses, or at a minimum the eye is straining and gets inconsistent focus (ie the front sight 'fades').

The answer is to us a slight positive diopter lens - not enough to shift your focus to the front sight (that is too close, and the target will be completely fuzzy), but to a balance point between the sight and the target, referred to as the hyperfocal distance.

For pistols, this will usually equate to a +0.75 diopter lens added to any distance correction you may need.

Art Neergaard
ShootingSight
www.shootingsight.com

[TenMetrePeter]

Its also worth using proper competition manilla targets for practice not only for the lighting but also for cleaner holes. 10c a piece or less. You can get free lux meter apps for your smartphone which you can use to compare lighting directly on the target (if you can physically get to the target). They may not give an accurate lux measure but as a comparator they are not bad. Then your practice range will he nearer standard. Adjust your lighting and targets THEN you can start filing the rearsight after some more practice in standard conditions.

[old sparky]

There is some good information here. thanks. Questions

Front sight should be the width as the bull?

If I got a right lens set about +1 to see the front sight should my left lens focus be set for distance?

thanks

[deadeyedick]

Use a front sight that has the same apparent width as the black area on the target while looking through the sights aimed at the target. As I said earlier you will need to experiment to find the width that suits your arm length and sight radius as there is no given, it is an individual thing.

As far as a lens you need to attend an optometrist ( taking your pistol if possible ) and have your eyes checked in order to have a lens prescribed for the correct focal length to suit the distance from your eye to front sight. Don't consider choosing the diopter yourself...self diagnosis will end in failure.

The left lens would be better glass beaded making it opaque allowing light in ( therefore not causing unnecessary strain on the aiming eye ) but not playing part in the sight alignment process. Some can shot using both eyes and many cant.

If you were going to use both eyes to sight then it makes sense that a similar lens is prescribed for the left eye as well.

[Rover]

For you guys in the Phoenix area, Copper State Optical owner is a shooter and will be completely amenable to trying anything he feels will help. He is used by champion shooters in the area.

[Gwhite]

I went to a coaching clinic at the US Olympic Training Center few years back. One of the recommendations I hadn't run into before is to try to set up your sight picture like this:

Sub-Six Hold.jpg (18.06 KiB) Viewed 2873 times

This is a nice symmetric pattern that the eyes & brain can be trained to achieve automatically at a subconscious level. When I can do it (I've got 50 years of training to undo), it works very well. Part of the theory is that you are not thinking about it as three separate pieces, only as a whole. You still need to maintain focus on the front sight.

The difference in the brain is subtle, and if you've spent years thinking about keeping the sights aligned to each other & then keeping that parked under the black, it's going to take a while to grasp. When I can do it, A) it seems to offload my brain a bit, and B) I get a 10.

[Rover]

White is right!

But to answer your question:

"If I got a right lens set about +1 to see the front sight should my left lens focus be set for distance?"

The brief answer is, "Hell, no!" Why are you even thinking about your left eye? Cover the inside of the left lens with matte scotch tape to admit light without vision.

Also, where did you get the +1 diopter from? Normally shooters would use 0.5 to 0.75.

If your eyes are OK (see a Doc) you can find suitable glasses at a 99cent store. If you need a scrip (astigmatism?), just have the correction added to your distance and forget the left eye.

For quick and dirty (but perfect) notch widening, buy a 3/16" chain saw file at the hardware store and hog out your rear notch until you've cleaned it up to a half moon. It worked well enough for the Russians to kick our asses for MANY years.

[old sparky]

When I used the +1 I was using that number as a example. Last year when I got glasses I had my optician make me a pair of single vision glasses that focus at 40” for looking at a PC screen while doing electrical testing. I have tried using those for shooting. the front sight is perfectly focused but the target is so fuzzy it doesn’t appear round. Couple weeks ago I went back to get glasses. I described how the target was a blur. He said he would make me a set with a little less magnification thinking I would still be able to see a nice sight picture while bringing the target back into a little focus so its recognizable. The glasses came in this week but the lab didn’t get the prescription of the left lens correct. the left lens came in .5+ more than the prescription. I took them anyway so I could try out the right eye looking at my sights and target. They will change the left lens to anything I want. Im just not sure what that will be. It was an experience looking thru these with both eyes if I left both eyes open my left eye wanted to be dominate.

thanks

[deadeyedick]

I have tried using those for shooting. the front sight is perfectly focused but the target is so fuzzy it doesn’t appear round.

You should have stuck with the first pair. You are not supposed to be looking at the target at any time or in any way...should be blurry and even distorted.

[deadeyedick]

buy a 3/16" chain saw file at the hardware store and hog out your rear notch until you've cleaned it up to a half moon. It worked well enough for the Russians to kick our asses for MANY years.

Here is what Rover was talking about. Pictures 2&3. I am sure that even not used as much nowadays the dished rear notch will still work as well today as it did in the past.

[TenMetrePeter]

If the target is far too blurred for your liking when the foresight is sharp you can experiment with small iris plates. You can start by drilling a 2mm or 3/32" hole in a piece cut out of a Coke can and hook it over your right lens. Take care not to scratch your lens! Try larger holes.
you can also buy self adhesive ready made ones.
You will lose light but gain depth of focus.

[ShootingSight]

The correct answer is +0.75 added to your distance prescription for your aiming eye, and a translucent blinder for your non-shooting eye.

Eye doctors are normally NOT the people to go to to discuss this. They are good at getting you to your correct distance prescription, but the math for helping you focus for shooting is outside their normal expertise and technique.

Doctor's expertise is in helping you focus ON an object, but falls short when you have two objects at different distances, and you want to focus between them (or on both at the same time, said another way). Further, their normal technique of trying to find the right lens by guessing a little more power or a little less power is a poor approach. Outside of shooting, the human eye never tries to manage depth of field to focus on multiple distances at the same time, which is why eye doctors are not used to trying to solve this problem. Interestingly, photographers get it right away, because they do manage depth of field.

In reality, optical physics knows how to solve this problem using the formulas for hyperfocal distance and the lensmaker's equation to come up with an exact diopter value.

Cutting through all the math, it really comes down to taking the average of the lens needed to focus perfectly on the rear sight of your pistol, and focusing perfectly on the target. This will result in a sight picture where the front sight is slightly sharper than either the rear or the target, but will still leave the rear and the target in sifficient clarity that you can form a good sight picture.

Diopters are the inverse of focal length, in meters. So a 2 diopter lens will focus you at 1/2 meter, a 3 diopter will focus at 1/3 meter, etc. It also works for fractional diopters. 3/4 diopter will focus at 4/3 meter = 1.33m.

Assuming you have good distance vision, the lens to see the target can usually be rounded to zero diopters. A 10m target would require a 0.1 diopter lens, but the human eye can usually only see steps as small as 0.125 diopters, so it is essentially the same as 0. Any target further than 10m is even closer to 0. The rear sight, for me, is about 24" away from my eye. This is 0.61 meters. To focus at this distance would require a 1/0.61 = 1.64 diopter lens.

So if I average 1.64 and 0 (or 1.64 and 0.1, if you want to be technically correct), you end up at 0.82 or 0.87 diopters would be my perfect shooting lens for a pistol with iron sights.

There are few places I have found that will custom grind lenses in 1/8 diopter steps, so a 0.875 is not impossible, but difficult to find. Common lenses are available in 1/4 diopter steps, so you would round down to a +0.75.

If you do need distance correction, especially if you have astigmatism, you would take your prescription, and simply add +0.75 to the sphere value, leaving the cylinder and axis unchanged.

Using a +1.00 would bias your focus to the sights, and blur the target unacceptably. Using a +0.50 would bias your focus to the target, however your eye muscle can exert to add power in your eye, so you can still get a good sight picture, but it is with your eye muscle slightly exerted, which can lead to fade of your sight picture, and would result in vertical stringing.

Non aiming eye should be blocked with something translucent, not opaque. Your pupils have sympathetic dilation, so if you have one eye seeing light and one eye seeing dark, both pupils will dilate to a level half way in-between, which means your shooting eye is too dilated, overloading it with light, and robbing you of depth of field, which ruins focus. Scotch tape keeps both pupils consistent with brightness.

[Gwhite]

+0.75 is a good place to start, but it may not be perfect for a variety of reasons. It is a compromise that moves the eye's relaxed focus from infinity to where you can focus more easily on the front sight, without making the target or rear sight too blurry. Depending on your stance, length of arms & sight radius, you may be off slightly, but it usually doesn't matter much.

HOWEVER, it is not the whole story. You need to be able to focus on the front sight without straining your eyes, and +0.75D will usually do that. You also have two other pieces to the puzzle; the rear sight, and the target. Ideally, you would also like the rear sight to be reasonably in focus, and the target not too blurry. This is where "Depth of Field" (DOF) comes in.

"Depth of Field" is a function of the "aperture" of the optical system, i.e. the size of the hole the light goes through. DOF is the range of distance over which you have acceptable focus, and it expands as you make the hole smaller. The extreme example is a pinhole camera, where you have sharp focus over a very wide range of distance (but very little light getting through...).

If you shoot with just a corrective single lens, DOF will be set by the size of the iris in your eye, which will vary dramatically with the lighting conditions. In bright light, the iris will close down, and your DOF will increase. You may be able to see your rear sight fairly clearly, and even still have the target be reasonably sharp. In dim lighting, the iris will open up, and your DOF will shrink. The target will get increasingly blurry, and your rear sight may get fuzzy too.

You can control DOF through two techniques: filters or an aperture (or both). In bright light (like outdoors), you can reduce the DOF by adding a dark filter in front of the lens. Many shooters find it much easier to stay focused on the front sight if they CAN'T focus on the target. Adding a filter on a sunny day can force the iris to open up, reducing the DOF so that the target is beyond the distance where you can focus. A small aperture can also reduce the light going into the eye. However, if the aperture is too small (smaller than your iris), it will begin to INCREASE the DOF again.

In low lighting conditions (like a poorly lit indoor range), your iris may open up to the point that the target is REALLY blurry, and the rear sight is very fuzzy as well. A filter won't help, but you can increase the DOF by using an aperture that is smaller than the eye's iris. The downside is that you are also reducing the (already somewhat inadequate) amount of light going into the eye, which can be fatiguing.

If you have a regular pair of glasses with a +0.75D lens correction, you can use clip on dark glasses, or tinted safety glasses over your corrective glasses to introduce filtering, but your options on darkness are pretty limited. You can buy fixed aperture stickers (EyePal), or adjustable clip-on (Gehmann) or suction cup (Merit) apertures to attach to your glasses.

The alternative is to get dedicated shooting glasses (Champion, Knobloch, Jaggi). These can use clip on filters, and an adjustable iris simultaneously.

Now, back to the +0.75D business. If you have the option of using filters & an aperture, you may find that you can get a better combination of front sight, rear sight & target focus by using a different correction and tweaking your DOF to suit. Also, your eye is not a fixed lens, and over the course of a match, the range over which it can focus can vary. I find that my eyes change enough that what works at the beginning may not be ideal by the end. In effect, my prescription is changing. This often manifests itself by slowly being able to extend my focus out to the target, which is doesn't work well for me.
I have a really hard time staying focused on my front sight IF I can see the target clearly.

I wear contact lenses, and my shooting eye is corrected for good distance vision. I'm in my mid-60's, and have presbyopia, which means I can't focus in close. I have to wear shooting glasses of some sort, or I'd never be able to see my sights. Two examples that work for me (YMMV):

1) Indoor pistol: Most of the local ranges do not have super bright lighting, so I don't use any filter. I use a +1.0D lens, with my aperture closed down so that my DOF extends past the front sight, but there is no way I can focus clearly on the target. As my eye muscles stretch and/or tire, I can adjust the aperture to suit.

2) Outdoor pistol (typically free pistol at 50 yards): Most of the time, the light is very bright. I use a +1/.3D lens, with a dark filter. if it's cloudy, I can switch to a lighter filter. In theory, the +1.3D lens should bring my focus in to about my rear sight, but between the bright light making my iris small, and adjusting my aperture, I can find a combination that gives me a DOF that has my front sight nicely in focus, the rear sight also crisp, and the target slightly blurry, just the way I like it.

The downside of all the added flexibility of throwing filters and apertures into the mix is that you can drive yourself nuts (and/or broke) playing with all the variables. At least now you (hopefully) have a better understanding of what the variables are & how they interact.

NOTE: One thing to watch out for is that most regular glasses are not very precise. A tolerance of +/- 0.25D is not uncommon. I've used my optometrists "lensometer" to check my shooting glasses lenses, and 0.25D is the finest graduation on the dial. With modern manufacturing, I think the tolerances are improving, but I've had lenses that were way off in the past. The correction may also vary a bit over the lens. What is important for shooting is the correction through the relatively small region in the center of the lens.

You can set up a home brew measurement system to check your lenses using a long dark hallway or basement, and a small bright light source (I use a Mini MagLight with the reflector removed). You park the light source as far away as possible, and move the lens back & forth until you get a sharp focus on the opposite wall. The Diopter rating of a lens is given by:

D = (1/O) +(1/I)

Where "O" is the distance from the light to the lens, and "I" is the distance from the lens to the focused image (everything in meters). If you have a light that is far enough way, the "O" term becomes negligible, but it has to be bright enough to allow you to see the focused image clearly. My basement is ~ 15 meters long, so neglecting the "O" term adds a ~ 6% error. If you can wait until mid-day, you can also try to focus the sun on the ground. That is bright enough that you can also add an aperture to evaluate only the portion of the lens in the center that you will be looking through. A piece of opaque tape with a 1/4" (6mm) hole is good, but you may find it hard to see the focused spot. Some shooting glasses lens vendors will sell lenses in 1/8 diopter increments. I've tested all my lenses, and even the "fancy" ones are often off by more than 1/8D.

[old sparky]

WoW, the information you are giving me is amazing. Thanks! It’s amazing the complexity of our eyes. I started looking into the eye glasses a year ago because I couldn’t see my ruler mkII sights. Joint problems were making it where 45acp was imposable to shoot. I sold what hurt. I thought about getting air pistol to shoot in the shop since I don’t get to the range as much as I would like. This has opened up a hole new realm.
What I experimented with today. I used my glasses that focus at the front sight. made a blinder from card stock for the non aiming eye. Cut out a soda can that would clip onto the aiming eye and punched a hole in the center of that. I tried 1/8” and opened that up to 3/16”. I have shot a few targets and this works really well. This makes me think how nice it would be to have the perfect lens correction with a aperture with the correct diameter opening. I think I will buy one of the clip on adjustable ones. Which one? Thanks for the input. I will re read this several times. I won’t ever be a master pistol shooter but I can improve and you all help cut down some frustration and time. So many variables but I am curious to see if I can add points to my scores at a shoot.


thanks for your help

[Gwhite]

The only clip-on continuously adjustable aperture I'm aware of is the one sold by Gehmann (Model 390). It pays to shop around, or keep an eye on auction sites, because they are pricey. I noticed they also have one with a suction cup (Model 393), and an add on filter set (Model 392) that fits the 393..

Champion's Choice has the 390 for $57, which is a pretty good price. I've seen some places asking close to $100:

http://www.champchoice.com/store/Main.a ... s&item=390

Midway sells the Merit with the suction cup for about $60. If the Gehmann fits your glasses OK, it's much more secure & less likely to pop off at an awkward time.

One other option that I haven't seen for sale in years is a clip-on aperture with a rotating wheel. The wheel is offset, and there are a series of different sized holes in it for you to select from. If you are handy with small mechanisms, it wouldn't be too hard to build one.

[David M]

For my own shooting, I found the adjustable Iris did not suit all events and I am better off with tints.
I use two lens of similar power, the non shooting eye is partly blanked out with Magic tape.
Using two lens helps reduce eye fatigue over a long shooting wekend.
Both 0.5 and 0.75 powers are used, 0.5 for Air and 0.75 for 25 and 50m.
I use yellow tint for low light, clear anti-glare indoors and grey tint for bright daylight or spotlights.
Play with the lens during prep time and select the best for the day.

[Rover]

World Champion Don Nygord said:

"As a follow up on the shooting glasses tip, we are going to talk about the sights themselves that you are trying so hard to see. The most common type of “iron” sights, those required by international shooting rules, are the “partridge” type — a square rear notch and a square post front. There are other types — notably the “U” notch rear sight — used by some of the top European shooters. The “U” notch is interesting in that if you make a windage error in aligning the front sight with the rear, it shows up as a change in the height of the bar of light on the error side, as well as a change in the width of the light bar. See figure 1. I used this type of rear notch for several years when shooting Free Pistol, including when I set the National Record of 574."