Iron or scope class

[SchuetzenDave]

Does light affect visual acuity?

At all blur and luminance levels, visual acuity decreases gradually for contrast levels down to 20%, and decreases sharply for lower contrast levels. Over the range of background luminances we tested (75.0 to 0.075 cd/m2), visual acuity decreases linearly with reductions in luminance.

Visual acuity is greater with higher light intensities than with low light intensities, and at low intensities.

So to shoot better you need to improve your visual acuity by increasing light levels to your eye.

[bpcrshooter62]

ok dave so are you saying by using the largest rear aperture you will shoot better than using the smallest rear aperture ?

[SchuetzenDave]

Yes, greater amounts of light to your eye provides the best acuity as long as it is not intense light.
Up until you reach the point of too much light that causes glare that will reduce that acuity.

Another issue that affects your sight acuity is oxygen in the blood.

When shooting offhand it is recommended to fire within 7 seconds.

The oxygen in your eye depletes once you delay your breathing and the acuity of your eye drops with the declining oxygen.

So light to the eye and oxygen to the eye affect sight acuity and ability to see precisely.

[Woody]

As an illustration, I have shot turkeys at Raton with no front sight insert. I used the hood as the aperture and shot 13 of 15 at Raton. You can't hit what you can't see. With my "new eyes", the targets are black again, but I still like a large aperture front and rear.

Woody

[bobw]

Does light affect visual acuity?

At all blur and luminance levels, visual acuity decreases gradually for contrast levels down to 20%, and decreases sharply for lower contrast levels. Over the range of background luminances we tested (75.0 to 0.075 cd/m2), visual acuity decreases linearly with reductions in luminance.

Visual acuity is greater with higher light intensities than with low light intensities, and at low intensities.

So to shoot better you need to improve your visual acuity by increasing light levels to your eye.

Makes sense to me, I usually use one of the larger openings on the Hadley and only change that for ambient light conditions. Just about allways have my largest aperature in the frt as I want light around the target..bobw

[ian45662]

Maybe it’s just me but when I close down the rear aperture and limit the amount of light that comes through, the animal in the front aperture become more defined. The bigger I go on the rear and the less defined the target is. Having said that I DO focus on the front aperture but I like the target to be defined as possible since they are somewhat odd shaped little critters.

[Woody]

Ian,

I think you still have "young eyes"

Woody

[From Along The Trail]

With a different way of thinking on using my sights, I have really seen that I was somewhat confused at being able to see a target.
So yesterday I had the chance to watch my target at 1000 yards. I have a test sight tube that I put into place, and let it sit there during the day. From 9 am with sun to my back, I was able to see 1’ square target real good. Then as the day continued on, I could test my ability to see the target, with the sun moving across my left shoulder. About 1:30 in the afternoon, the target was now in shade. As the sun passed from shining on the front to the rear of the target. With the sun to the rear of the target, that sorta represents a cloudy day. Or a cloud passing over the target.

I have realized that I was only testing my ability to see the target, when I went to the range. I never thought to work on this part of shooting, when I had time before going to the range.

[SchuetzenDave]

ian45662 You missed the advice I presented earlier; originating from Lones Wigger, the most successful Olympic shooter ever, Olympic Coach and Coach of the Vietnam War snipers.

A sharper target has your eye concentrating on it instead of concentrating more time on centering the target in the front sight.
Forcing the eye to committing more time to centering of the target comes from having a sharper front sight and a less sharp target image.
It means your eye acuity is being used to center the target (most of the time) opposed to figuring out what the target is (with young eyes or old eyes).

Go ahead like most of us and always pursue the sharpest target by using a smaller aperture - but your groups sizes will be three times larger.
I learned how to shoot irons with great precision - and it definitely was not with a sharp front target.

Using Lone Wigger's advice I was the International Schuetzen Benchrest Champion in 2008 and 2013 using iron sights and slow moving cast bullets in single shot rifles.

[mike herth]

I'm really appreciating this discussion, thanks Dave, et al. I wish more of the top shooters would weigh in. I have more experimenting and learning to do in in proper sight picture and mechanics of shooting. Oh, and determining wind and other environmental adjustmens.

[SchuetzenDave]

Some basic rules I use for wind:

1. Sight your rifle to shoot on the consistent and the constant wind condition
2. Avoid winds coming or going at 45 degrees since the wind drift will be twice what a 90 degree cross wind or a straight forward or back wind drift will cause.
3. Always avoid shooting when the wind is increasing. Time your shot to coincide with a dropping wind velocity.

In the Schuetzen game you learn how to dope and adjust your shooting to wind conditions since you have to hit the bullseye precisely.
The above basic rules will significantly help your scores when judging wind condition.

Wind charts show how the bullet deviates with the wind direction at the time of shot. This is valuable to understand the up and down and sideways direction the bullet deviates depending on the wind direction.

[Aviator]

Dave, that chart mostly makes sense to me.
The one thing that I don't understand is the large vertical jump that it shows from a 7 o'clock wind to a 6 o'clock wind.

[semtav]

Some basic rules I use for wind:


2. Avoid winds coming or going at 45 degrees since the wind drift will be twice what a 90 degree cross wind or a straight forward or back wind drift will cause.

Could you explain that one better Dave?

[SchuetzenDave]

When you sight in for a specific wind condition you compensate for the direction left or right by adjusting for the constant wind being experienced.
When sighting you also compensate for elevation depending on wind directly at you or away from you.

Changes to where your bullet goes depends on changes in the wind velocity and angle of the wind from your point of aim you have sighted in on.

An increase in wind will move you a certain distance left or right.
However a change in wind and a change to a 45 degree wind will result in moving the bullet twice as far from your point of aim.

When shooting on a target trying to hit a bullseye you may loose a point by moving one inch from a wind change left or right.
However if the wind change is diverted by 45 degrees to you or away from you that wind change will result in a a 2 point loss since it will move it two rings.

Schuetzen shooting is precision shooting and you learn to read the wind and understand what wind variations do to where your bullet hits.
This is also dependent what wind condition you sighted in to.

However the same principles apply to determine if the bullet is going to hit a silhouette at long range.

[SchuetzenDave]

The 7 to 6 O'clock jump shows what happens from moving to a 45 degree angle causing a major change in where the bullet hits.

So you also learn to hit directly on a straight wind to or away from you and avoid even a slight change in the angle of the wind because it causes major differences where the bullet will hit.

I always prefer using a left right wind since it is safer to shoot on.
However a straight wind can record absolutely great scores as long as you can time it to shoot when it is absolutely straight to you or away from you.