Advanced Marksmanship Does target shadow have an effect on dope?

[david8989]

So I ran into a situation the other day that I haven't experienced before. I was at the range in the afternoon and was getting target shadowing due to all the berms shading the steel, and thus was needing to bring my dope up anywhere from .1-.2 to compensate. This happened to me both at 542yds on steel and 98yds on paper (target distances were all confirmed with a terrapinX). I checked my dope out at the 790yd berm which was still in normal sun, and the rifle was a spot on match to my 4dof kestrel's solution and what I expected. So the only way I could explain this issue is if the opposite of target shimmer, which will give you the optical illusion of the target being higher than it really is and make you impact high, was occurring. So does target shadowing have the opposite effect and make you impact low? I have googled my ass off to try and find the answer to no avail, but inquiring minds need to know, does it???
**Edited for clarification**

 

[theLBC]

i would have to guess is it optical and not dope.

 

[david8989]

i would have to guess is it optical and not dope.

Right, that's what I meant. Sorry for the confusion, I'll try to clarify the post. Have you seen that effect before?

 

[theLBC]

Right, that's what I meant. Sorry for the confusion, I'll try to clarify the post. Have you seen that effect before?

no, not personally.

 

[DaleAGribble]

Successful Fclass guys generally know quite a bit about this, one of them put it to me the best I've ever heard it.

When it comes to long range shooting and everything external ballistics:

Drop = science
Wind = art
Light = vudoo

 

[Steel head]

Drop = science
Wind = art
Light = vudoo

That sums it up nicely!

I’ve seen some goofy things from light.
Bright days with snow on the ground come to mind.

 

[crowdog7]

Back in the 90's I shot a LOT of highpower which was, of course, open sights. When cloud cover came & went, the target appeared either larger or smaller, depending on light conditions. It definitely made a difference in elevation.

 

[1moaoff]

 

[alex2x2]

i faced the same problem. Target seemed higher than it really was.

It was higher about 0.4 mil on 500m

 

[THEIS]

Hi,

The old saying of "Lights Up Sights Up, Lights Down Sights Down" still holds true to this day.

Sincerely,
Theis

 

[msstate56]

Hi,

The old saying of "Lights Up Sights Up, Lights Down Sights Down" still holds true to this day.

Sincerely,
Theis

I’ve heard this a thousand times, but no one ever explains it. In the context of modern precision rifles with say 5-25x scopes, exactly how does this saying apply and how do you adjust your sights? And in what conditions?

 

[alex2x2]

Hi,

The old saying of "Lights Up Sights Up, Lights Down Sights Down" still holds true to this day.

Sincerely,
Theis

Can you explain that please?

 

[Conaso]

I may be wrong but from my notes of others' comments.

Light intensity and direction doesn’t directly impact bullet trajectory but changes perception of the target. On a vertical plane, shooting with lower light-intensity compared to when zeroed, POI goes high. Shooting with greater light-intensity compared to when zeroed, POI goes low. So, light up – sight up; light down – sight down. Generally, adjust .25 MOA/0.1MIL at 100 yards/meters plus, and .75-1.0 MOA/0.2-0.3 Mil 600 yards/meters plus. On horizontal plane, changes in light direction causes an illusion commensurate with the direction the light. If the light comes from the shooter’s right, adjust sight (right) toward the light, and vice-versa. Generally, adjust .25 MOA/0.1MIL.

 

[308pirate]

, exactly how does this saying apply and how do you adjust your sights? And in what conditions?

Ladies and gentlemen, and here we have yet another reason why keeping a data book or notes of observations of every shooting session is critical.

Those of you who think the magic electronic box contains ALL of your answers are usually the ones asking the quoted question.

 

[alex2x2]

I may be wrong but from my notes of others' comments.

Light intensity and direction doesn’t directly impact bullet trajectory but changes perception of the target. On a vertical plane, shooting with lower light-intensity compared to when zeroed, POI goes high. Shooting with greater light-intensity compared to when zeroed, POI goes low. So, light up – sight up; light down – sight down. Generally, adjust .25 MOA/0.1MIL at 100 yards/meters plus, and .75-1.0 MOA/0.2-0.3 Mil 600 yards/meters plus. On horizontal plane, changes in light direction causes an illusion commensurate with the direction the light. If the light comes from the shooter’s right, adjust sight (right) toward the light, and vice-versa. Generally, adjust .25 MOA/0.1MIL.

Are you saying about light without mirage, are you?

 

[6.5SH]

 

[msstate56]

Ladies and gentlemen, and here we have yet another reason why keeping a data book or notes of observations of every shooting session is critical.

Those of you who think the magic electronic box contains ALL of your answers are usually the ones asking the quoted question.

Man that was a ton of help. I’ll write that down in my data book.

 

[msstate56]

I may be wrong but from my notes of others' comments.

Light intensity and direction doesn’t directly impact bullet trajectory but changes perception of the target. On a vertical plane, shooting with lower light-intensity compared to when zeroed, POI goes high. Shooting with greater light-intensity compared to when zeroed, POI goes low. So, light up – sight up; light down – sight down. Generally, adjust .25 MOA/0.1MIL at 100 yards/meters plus, and .75-1.0 MOA/0.2-0.3 Mil 600 yards/meters plus. On horizontal plane, changes in light direction causes an illusion commensurate with the direction the light. If the light comes from the shooter’s right, adjust sight (right) toward the light, and vice-versa. Generally, adjust .25 MOA/0.1MIL.

Thanks for the detailed response. What you described is what I have observed with sun at low angles on the left or right. I generally try to check my zero at midday, which seems to eliminate my left/right deviation.

But back to the original question- I’ve noticed a phenomenon at matches that is similar. Head sized plates that are located inside of a van at ~450 yards. I spot a lot of shots going high, I can only guess due to the plates being in the shade inside the van. I’ve had my best results by aiming low on the plates on that particular stage.

 

[smoothy8500]

The "Light's up, sights up" saying has been a maxim in Highpower shooting for basically the entire history of the sport. The explanation was usually related to the 6-O'clock hold and either sunlight glare on the front sight surface or narrowing of the eye's pupil enhancing front sight focus. Despite the observation and saying's 100-year existence, it is virtually unknown outside of Highpower shooting.

What is interesting is the fact that the phenomenon is repeated with optical sights. I have observed it and documented it with both the low-power 4.5X scopes used in Highpower, and also higher magnification F-class optics. Once again, databooks are key to proper Dope records.

 

[308pirate]

Man that was a ton of help. I’ll write that down in my data book.

Shoot more and write shit down, then you would know how this works

 

[Steel head]

Shoot more and write shit down, then you would know how this works

Even if I don’t go back all the time to refer to my notes writing stuff down sure helps me remember stuff.

 

[7mmMato]

I have noticed this as well when going from a black bullseye style target to shooting painted white steel. Would have a perfect waterline on the steel. When i switch to the black target to shoot a group the group would be low a couple of tenths 600 yd and 1000 yd.

 

[GrumpyOleFart]

The lantern test.
Different coloured lights set at the same distance with same diameter, appear to be different sizes.

 

[Deleted member 113831]

So does target shadowing have the opposite effect and make you impact low?
**Edited for clarification**

There are too many variables to give any absolutes.
The target image deflects in the direction of the warmer air.
However, the light condition you zeroed in makes a difference, and whether you are shooting from the same temp gradient the target is in.

 

[salks]

Learned a valuable lesson one day. It had been a hot sunny day. Breif little rain came through cooled things down. I was prone shooting a 600 yrd chip shot basicly. Watched my first 2 shots go over the target. Couldnt believe it ,i was on it, knew i squeezed off some good shots, knew i had my shit right. I was extremely frustrated ended up blowing the rest of the stage. Luckily i was shooting with a really good shooter he explained what might be happening some type of ground miage. He had seen his shots hit high and adjusted. I asked him what the fuck i am i supposed to do about that , i was still just kinda pissed at myself, he said aim lower. Just one more thing that may require some adjustment on the fly.

 

[Deleted member 113831]

Learned a valuable lesson one day. It had been a hot sunny day. Breif little rain came through cooled things down. I was prone shooting a 600 yrd chip shot basicly. Watched my first 2 shots go over the target. Couldnt believe it ,i was on it, knew i squeezed off some good shots, knew i had my shit right. I was extremely frustrated ended up blowing the rest of the stage. Luckily i was shooting with a really good shooter he explained what might be happening some type of ground miage. He had seen his shots hit high and adjusted. I asked him what the fuck i am i supposed to do about that , i was still just kinda pissed at myself, he said aim lower. Just one more thing that may require some adjustment on the fly.

What you were experiencing was the sudden reduction of target refraction. The target deflects in the direction of the warmer air. You zeroed with the target image appearing lower than actual. When the rain cooled everything off you were seeing the target closer to it's true higher position and therefore your rounds sailed over.

The exact same thing can happen when the sun is suddenly covered by clouds...or when you have two targets at exactly the same distance, but one is in shadow.

 

[SanPatHogger]

Thank guys very much for asking this question and discussing it.
I shot at 400 yards last night and had a very large shift high and right. Exact same spot I shot 400 last time.
Shot a nice group but was way off.
The time laps video appears to be what happened.