"Sun up, sights up, sun down, sights down"
Nicole Hamilton
Nicki
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bwatson
As I remember from my National Match and Palma competition days, it refers
to the fact that on a sunny day your point of impact will usually be a bit
lower as the target is more clearly visible. On a bright day you hold a bit
lower on the tgt blur as it is more clearly visible. By the same token, on a
darker day you tend to cheat the front post up into the bullseye as it is
less distict.
Hence, sun up-sights up-you raise your point of impact as you will actually
be aiming lower on the tgt, sun down-sights down, lower your point of impact
as you are actually aiming a bit higher on the bull.
My opinions and recollections are always subject to error so please seek
independant comfirmation.
BTW, my sight adjustment was to turn the rear aperture on the M1A up for
sunny and down for dusk once zeroed. They were NM sights.
Bill
Bill Barott
for everyone. Probably much depends on your hold, whether you hold
'line of white' or actually touch the front sight to the bull. If you
hold 'line of white' as I do bright, overhead lighting will make the
'line' appear fatter and I will 'push the bull'. Ergo, the sights have
to come down, which is exactly the opposite of what is alleged to
occur. But, the effect probably works as described if your normal sight
picture is to 'touch the bull'.
Under low, slanting sun conditions I do have to click into the light.
The reason I click into the light under angled-light conditions is the
side of the front post opposite the light tends to disappear in these
conditions, shifting my point of aim away from the sun.
Jim Owens has a 3-4 page discussion of lighting effects in his boot
'Sight alignment, trigger control and the big lie', it's worth a
perusal.
Naturally, aperture sights pretty well eliminate this effect.
Nicole Hamilton wrote:
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John Kepler
Nicole Hamilton wrote in message <953n16$9o$1...@xring.cs.umd.edu>...
> ...
To be pedantically correct, it's "Light's up, sights up; light's down,
sights down!".
When you go from diffuse or overcast light to bright sunlight, optical
factors will cause your normal sight picture to shift your Point Of Impact
downward from one to two MOA.....the farther back you get, the more
pronounced the effect is. It can be a REAL problem at 1000 yds, but is
noticable at 600. To compensate for the optical effect, you come up a click
or two when you transit from overcast to bright sun. Ditto in the reverse
if you are zeroed in bright sunlight and you transit into overcast...you
drop down one or two.
John
> ...
Michael Loscalzo
This does not pertain to scopes or aperature front.
When it is very bright, shooters find the contrast too harsh between their
front site and the black bull. They have a tendency to put a little space
below the bull.Therefore their shot will go low; requiring a sight
adjustment UP.
When the contrast is good, they snuggle that post right up to the bull.
Then their shot will be high, requiring an adjustment down. Thusly "Sun
up, sights up, sun down, sights down"
--
<<<<<<"If you don't stand up for your rights NOW; you won't have any rights
to stand up for LATER">>>>>>
skidmark
front sight, that creates a false impression on where the front sight is
actually located. There will be a "double image", or "mirage" , if you
will. This will make you aim a little lower, as you place the "mirage"
image underneath the bullseye. ( this is if you are using a 6 O'clock hold,
instead of the "Navy", or point of aim, hold) This will incurr at least a
minute, or so, inaccuracy in sighting, as you will be aiming low.
Therefore, a couple of clicks up, or so, will help you overcome the error.
Always make sure you black up your sights real good with carbon, or a match,
before doing any serious shooting. Make it a habit, and you'll not be
disappointed when the sun does come out from the cloud.
The reverse is true, if your sights are elevated for the compensation
of "mirage", when the sun is "down". You will have to adjust your sights
accordingly. This means a downward turn of the elevation knob is in order,
IF your sights were adjusted upward for "sun up" conditions. This is really
where a record book of High Power is an asset.
If you record all of your shots, and the condition they were shot in, it is
a simple matter to duplicate the sight settings at a later date.
Course, if you shoot like I do, the last thing in the world you would
want to do is to be reminded of them :-)
flimflam on wife's computer
flim...@xtalwind.net
#Can anyone explain this tip for rifle competition, please?
Jeff/addesign
#Can anyone explain this tip for rifle competition, please?
Other replies may be more technical, explaing why. This is what I've
found from experience. My summer HP league starts shooting at 5:30pm,
so we think of ourselves as better "night fighters." By end of summer,
second relay is almost shooting in the dark. Sometimes, we compete in
regionals or weekend matches, in broad daylight! My solution is to
adjust sight picture, not change elevation.
Bright sunlight: center of mass. Front post splits the bull.
Evening, overcast, rain, or other poor light: Lollypop. Bull sits on
the post.
Some of my shooting buds will adjust the sight, and not change the
sight picture, reasoning that centering the post is easier with a
center-of-mass hold. But I find this harder to see in dim light.
Jeff/addesign
NRA Certified RSO
ISRA,Tuesday Night Irregular Rifles, High Power League
arn_werks
The advice given to me was simply to shoot or fade toward the
light because glare wipes out a portion of the visible edge
toward the light.
Not very scientific explanation but Bill Pohl and Earl Waterman,
former AMTU rifle and pistol shooters used to help me a lot and
that was their advice for any post front.
Light can also mess with target edge contrast and fuzz edges
depending on direction and brightness. Takes a lot of staring
at a target on bright and overcast days to learn.
Cordially,
Red
Nicole Hamilton wrote:
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