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View Full Version : Can someone explain my experience with red-dots


Whiterabbit
09-05-2011, 10:30 PM
Hi guys,

Here's what red dots do for me:

I set a red dot on a table and point the red dot at a target maybe 10 yards away. Without touching the red dot, I move my head so the dot shifts location inside the tube or heads up display (I've tried both). What happens is that the point of aim (what the dot is covering, the target) also shifts.

I thought the point of the red dot was that as long as you could see the dot, the bullet goes where the dot is pointing at?

Distance to target doesn't seem to matter, different models didn't seem to matter. They all seem to be "shifty". Meaning I have to eyeball the dot into the center of the FOV of the sight and hope I'm "close enough".

It's never close enough.

Was I just mis-told about the concept of see-dot, bullet-hits-dot?

Pthfndr
09-05-2011, 10:35 PM
Have you actually mounted it to a gun and shot with it yet? They aren't made to be mounted to a table.

bjl333
09-05-2011, 10:56 PM
Have you actually mounted it to a gun and shot with it yet? They aren't made to be mounted to a table.

What caliber is the table?!?! :p




JK ... Go mount it and shoot it!!

The dot will be on target! As your head move you're changing the angle of the sight, when mounted on a gun the prespective will change to the point of impact. Unless you have a cheap red dot!!

carnelianbay
09-05-2011, 10:58 PM
A good red-dot will have no issues even near the side of the tube.

What I did find out about red-dots is that if the dot doesn’t appear to be perfectly round then it could be your eyes. This is what happened to me. I spent big bucks on a CompM4, mounted it, and the dot was oblong. Crud… I called aimpoint and they told me to rotate the optic. If the shape stayed in place (didn’t rotate with the optic) then it was my eyes. Sure enough it was my eyes. This effect is less pronounced with both eyes open (which is how you should use a red-dot anyway). Every red-dot I’ve looked through since has the same oblong shape.

Whiterabbit
09-05-2011, 11:34 PM
Have you actually mounted it to a gun and shot with it yet? They aren't made to be mounted to a table.

Why would that matter? If I said I went to the range, mounted the red dot, rested the gun on sandbags, aimed at the center of a paper target, then without moving the gun or firing a bullet, moved my head and watched the red dot shift all over the target, would that change what's going on here?

In that case, I thought the red dot was supposed to remain aimed at the center of the target, regardless of where my head goes? (as long as the red dot is visible)

jonnietyler
09-05-2011, 11:46 PM
Hi guys,

Distance to target doesn't seem to matter, different models didn't seem to matter. They all seem to be "shifty". Meaning I have to eyeball the dot into the center of the FOV of the sight and hope I'm "close enough".

It's never close enough.

Was I just mis-told about the concept of see-dot, bullet-hits-dot?

What you're seeing is parallax error. Have you tried an Aimpoint red dot? Aimpoint Micro H-1/T-1's are suppose to be free of parallax error.

However, when I aim my Aimpoint Micro and move my head, the point of aim does shift slightly, but a lot less than when I try the same test with my Primary Arms red dot.

esskay
09-06-2011, 12:45 AM
What you're seeing is parallax error. Have you tried an Aimpoint red dot? Aimpoint Micro H-1/T-1's are suppose to be free of parallax error.

However, when I aim my Aimpoint Micro and move my head, the point of aim does shift slightly, but a lot less than when I try the same test with my Primary Arms red dot.

FYI, none are 100% parallex free. Aimpoint says their sights are ninety-something percent though!

ejhc11
09-06-2011, 5:34 AM
The only red dots with the nearest parallax are the Eotechs around 22yds, Aimpoints are set 50yds as well as most red dots on the market.

Whiterabbit
09-06-2011, 7:55 AM
wow, disappointing. Maybe the best iron sights I can get my hands on is the way to go. Are there any tricks red dot manufacturers use to better ensure the user has the dot lined up in the center of the viewing window? Any tricks to minimize using the firearm in a parallax-generating position?

HK Dave
09-06-2011, 7:57 AM
Try it again with something farther away. Nothing is parallax free at 10 yards.

Whiterabbit
09-06-2011, 8:01 AM
Went to the range and zeroed and rezeroed at 15, 25, 50, and 100 yards on Sunday. Always seemed to be a problem. Using a cheap (and I mean cheap) borrowed red dot. tests with the good stuff was always at a shop aiming at the back wall of the shop, 10-ish yards, no distances, no mounting, no firing.

You are saying the good stuff would be parallax-free at a set distance (say, 50 yards), but show these signs of parallax both short of 50 and beyond 50? Do any red dots have adjustable parallax, or have them set for longer distances (say 100 yards)?

K_Labs
09-06-2011, 8:15 AM
I have a Doctor optic knock off and it's cheap but holds just fine at the indoor range. The nearest I shoot is around 10 yards and I think the back walls is at 25 yards. Never had any issues but it was with a .22 LR and I usually get similar cheek wield. Are you using a pistol?

Whiterabbit
09-06-2011, 8:32 AM
yes, a revolver. Trying to get out to 100 yards rested and trying to determine if a red dot will be better for this application than irons. I can get fiber optic front sights for $30, and Millitt rear sights (no idea if this would help anything) for something like $50 or $50+, but if they won't really help compared to OEM irons, I may as well spend many times over that value and go for a small form-factor red-dot.

IF it truly provides a benefit in terms of tight groups when rested.

ejhc11
09-06-2011, 10:11 AM
The red dots do work. You may need to try zeroing them at 25yds minimum at first. For my rifles I only have the cheapy priced (Primary Arms $120, and a Tasco BKRD30 $33 Walmart) and they do help you shoot better. I rough zeroed them at 25yds then fine tuned them at 50yds and they stay zeroed for 200yds. Even my 11yo kid who never shot an AR could hit the 200yd steel plates after his 3rd shot consecutively. It was point and shoot thereafter.

IntoForever
09-06-2011, 10:15 AM
Try the NcStar ones from the swap meet. Twitch and the dot drifts all over the place.

ejhc11
09-06-2011, 11:07 AM
Try the NcStar ones from the swap meet. Twitch and the dot drifts all over the place.

I got one of those $9 red dot NcStar for my kids Nerf gun and that didn't even hold up...

Maybe get the Bushnell TRS-25 from Amazon for $80 plus a $30 rebate? Seems like the best deal for a decent red dot.
http://www.amazon.com/Bushnell-Trophy-TRS-25-1xRed-Riflescope/dp/B00200E0HM/ref=sr_1_1?ie=UTF8&qid=1315335970&sr=8-1

d4v0s
09-06-2011, 11:39 AM
The issue with the dot moving all over is nothing to worry about. On a cheap red dot you have parallax and even the eotech and aimpoints have a bit.

What i want to know is why when your shooting your rifle, you feel it necessary to move your head all around... cheek weld is extremely important for consistency with any optic; another thing, Eotechs and aimpoints with their minimal parallax will allow you to hit a man sized target by simply looking at your sight from any angle. YES, they will not put good groups together when doing this, but that isnt the point of a red dot. Truly the red dot is for fast moving target acquisition and a max engagement range of 350meters. after that humans get small and the inconsistencies in the optics start to show.

dhyayi
09-06-2011, 12:23 PM
I got one of those $9 red dot NcStar for my kids Nerf gun and that didn't even hold up...

Maybe get the Bushnell TRS-25 from Amazon for $80 plus a $30 rebate? Seems like the best deal for a decent red dot.
http://www.amazon.com/Bushnell-Trophy-TRS-25-1xRed-Riflescope/dp/B00200E0HM/ref=sr_1_1?ie=UTF8&qid=1315335970&sr=8-1

I think so. This is a good deal

Coyotegunner
09-06-2011, 1:10 PM
The range I shoot at,a lot of 22 pistols have them for indoor 25 yd bullseye matchs.The cheap ones are fine on 22.The tactical guys mount them(a lot of C-Mores) sideways on a rail for ARs for close to 50 yds.They then have real scopes on top for longer ranges.I have used a few aimpoints on shotguns for coyotes to 70 yds.I think my next one will be Eotech.Point here is I remember a little weird stuff when trying to use one sideways.Still like and use a variety of them as well as 1-3 and 1-5 scopes.I prefer the scopes if I had to choose.

carnelianbay
09-06-2011, 3:12 PM
The issue with the dot moving all over is nothing to worry about. On a cheap red dot you have parallax and even the eotech and aimpoints have a bit.

What i want to know is why when your shooting your rifle, you feel it necessary to move your head all around... cheek weld is extremely important for consistency with any optic; another thing, Eotechs and aimpoints with their minimal parallax will allow you to hit a man sized target by simply looking at your sight from any angle. YES, they will not put good groups together when doing this, but that isnt the point of a red dot. Truly the red dot is for fast moving target acquisition and a max engagement range of 350meters. after that humans get small and the inconsistencies in the optics start to show.

^^^well said

Also note that at 50+ yrds the dot will be larger than the accuracy of the rifle.

TATB
10-05-2011, 1:30 AM
Hi, I am kind of scientific guy with an Eotech XPS. Here is my vision of the parallax problem.
Unfortunately, there are no absolutely parallax-free sights. Some rifle scopes are set parallax-free at 100m, some at 200m, and some are adjustable. From my understanding, quality red-dot sights (Eotech and Aimpoints) are set parallax-free at infinity, which I believe is the best choice. It means that the distance to the target is negligible compared to the distance to the reticle image.
The implication is that moving your eye 15mm to the left (half-width of the Eotech window) would shift the point of aim the same 15mm to the left irrespective of the distance to the target, and so on. Similarly, moving your eye 11mm up (half-height of the Eotech window) would shift the point of aim the same 11mm up irrespective of the distance to the target, and so on. You can verify this by looking at a distant target through your Eotech and a powerful binocular. If you zeroed your rifle with perfectly centered reticle the maximum possible error from non-uniform cheek weld is 15mm in windage and 11mm in elevation independent of the distance to the target. If your reticle is centered there is no parallax error.
The reticle position in the window may be different provided it is uniform. To control the reticle position you can use either the iron sights, or you can move the Eotech forward to better see the frame (at 2' the reticle covers the whole window). The position of the Eotech on the rail doesn't affect the reticle visibility - your eye must be within the same 30x23 window to see it.
If Eotech like many riflescopes was made parallax-free at 100m the parallax error would be zero at 100m, but double at 300m and triple at 400m (with opposite sign).
The claim that the Eotech sights are parallax-free at distances over 100m means that the maximal error is less than 0.5MOA, which exceeds the accuracy of the rifle and the shooter.
Nothing is perfect, even the sun has spots, and the Eotech has parallax errors, but we can live with it.

Droppin Deuces
10-05-2011, 6:39 PM
Red dots do not fix poor technique - they enhance good technique.

Merc1138
10-05-2011, 7:47 PM
Why would that matter? If I said I went to the range, mounted the red dot, rested the gun on sandbags, aimed at the center of a paper target, then without moving the gun or firing a bullet, moved my head and watched the red dot shift all over the target, would that change what's going on here?

In that case, I thought the red dot was supposed to remain aimed at the center of the target, regardless of where my head goes? (as long as the red dot is visible)

As people have said, yes it will be different. 10 yards is going to be too close for even a high end red dot unless it had it's parallax correction specifically set to be that short, and I've never heard of one like that(there might be, but I'm not aware of them).

Take that red dot somewhere and point it at a target 25-100 yards away, it will behave differently than it will at 10 yards. They are all like this.

Whiterabbit
10-05-2011, 10:20 PM
so then, would you folks suggest that a red dot on a pistol is pointless? The idea of keeping a sight picture within an 11x13mm area is not trivial without a stock to use as a crutch.

Merc1138
10-05-2011, 10:51 PM
so then, would you folks suggest that a red dot on a pistol is pointless? The idea of keeping a sight picture within an 11x13mm area is not trivial without a stock to use as a crutch.

It depends on what you're shooting at and how far away it is. You already have a small window to look through with iron sights on a pistol when they're lined up correctly. There just isn't a "frame".

Whiterabbit
10-06-2011, 9:13 AM
Right, let me be more clear.

I'm trying to understand the arguments put forth. What I read in what folks say, is that with a "proper cheek weld" OR a realistic eye position shift of ~.5 inches combined with a well designed tube red-dot @ parallax @ infinity, dot accuracy suffers not-at-all.

Great.

So my question extends now to non-tube style red dots on a pistol. In this example, there is no tube, the dot in my experience is still visible even when the eye is outside that .5" window, there is no stock to help align some sort of sight picture, and the dot itself is much farther away from the eye compared to a rifle. Thus, it is possible to "get the dot" on paper while being shifted out of that sub-moa alignment suggested in above posts.

Irons is a moot point because I have two points of reference to give me a "perfect" sight picture alignment. Not so with a red dot, I just get the dot projection.

Thus I ask: without a crutch (gun stock or tube as chassis) to help ensure (or force) visual alignment within that .5" window of view, wouldn't the red dot "not enable" moa accuracy with regards to point of aim? (which was my definition of "pointless", but let's get way from that word as too-negative)




-------

For the sake of argument (I suspect I'll see a bunch of posts saying "it's a pistol so you are shooting less than 5 yards anyways"), let's pretend the pistol is a very accurate model capable of shooting good groups at 50-100 yards (because it is and can). And that the ultimate goal is to improve group size at 50-100 yards without the use of magnified optics.

bombadillo
10-06-2011, 9:19 AM
Sounds like a parallax issue. Put it on a scope, put your gun on some bags or a rest. Start shooting. If you leave the gun on the rest, and move your head, shoot again. Red dot may be in a different place but its going to shoot through the same hole. That would be parallax. If you move your head and dot stays in the same spot, you're parallax free as one would hope. EOtech and Aimpoint are parallax free, some of the others like the reflex sights have short parallax like sub 15 yard issues or ultradots. Most are pretty good though.

caoboy
10-06-2011, 9:34 AM
How much have you practiced with a red dot? It's a sight, like any other. You need to zero, then practice your sight acquisition and build up a muscle memory for your hold, so your sight is on target every time. I don't understand why you think a rds will always be on target. If you move your head all around with your irons, you aren't going to hit anything either.

Merc1138
10-06-2011, 9:52 AM
Right, let me be more clear.

I'm trying to understand the arguments put forth. What I read in what folks say, is that with a "proper cheek weld" OR a realistic eye position shift of ~.5 inches combined with a well designed tube red-dot @ parallax @ infinity, dot accuracy suffers not-at-all.

Great.

So my question extends now to non-tube style red dots on a pistol. In this example, there is no tube, the dot in my experience is still visible even when the eye is outside that .5" window, there is no stock to help align some sort of sight picture, and the dot itself is much farther away from the eye compared to a rifle. Thus, it is possible to "get the dot" on paper while being shifted out of that sub-moa alignment suggested in above posts.

Irons is a moot point because I have two points of reference to give me a "perfect" sight picture alignment. Not so with a red dot, I just get the dot projection.

Thus I ask: without a crutch (gun stock or tube as chassis) to help ensure (or force) visual alignment within that .5" window of view, wouldn't the red dot "not enable" moa accuracy with regards to point of aim? (which was my definition of "pointless", but let's get way from that word as too-negative)




-------

For the sake of argument (I suspect I'll see a bunch of posts saying "it's a pistol so you are shooting less than 5 yards anyways"), let's pretend the pistol is a very accurate model capable of shooting good groups at 50-100 yards (because it is and can). And that the ultimate goal is to improve group size at 50-100 yards without the use of magnified optics.

As I said, with a pistol you have a small window to keep your eye within for iron sights already anyway. With a red dot or scope, you keep the center of the reticule centered within the optic.

No one said it was easy with a pistol.

Parallax still also applies to optics on pistols. Yes, people shoot pistols out to 100 yards and beyond, they also hunt with (big)pistols. Scopes and red dot sights are not some magical devices that will make you into a sniper or expert 100 yard bullseye target shooter. They all require technique that you need to learn.

It seems like you're trying to understand what the issues are and how to correct them with thought exercises, for something you have zero experience with. If you want to see how a red dot works on a pistol at 25 yards, go try it. If you want to see how the red dot for your rifle is actually going to work at a distance greater than 10 yards, try it.

Whiterabbit
10-06-2011, 1:43 PM
I took an inexpensive red dot out to the range on a pistol, and the questions I'm asking now are a direct result of that experience. Post #1 came from the time I spent mounting it pointing at the wall.

Thanks to yours and other discussions I've learned how certain more reputable models do a much better job of managing the parallax, but it's still not 100% of the puzzle, though you're definitely right, I'm trying to understand the issues (with almost zero experience) given the product has a $500 price tag! Hard to just go out and try it. :)

-----------

Here's what I'm gonna do. I'm gonna try to get some time sometime in the future at a shop with an infinite-parallax red dot and see if I can't point it out the window or something, and try to get a sense of how much the dot shifts with small head movements. I'm sure I'll be able to come back and ask more questions after that.

I understand that looking through the dot, it's not gonna be around the edge of the optic window. But for infinite parallax dots, I need to get a sense of how much the dot shifts with minor head shifts. Cause eyeballing that dot in the middle of the red-dot window is not really precise.

noone here has indicated yet though if it really needs to be. (or doesn't need to be?)

bohoki
10-06-2011, 4:13 PM
they have their sweet spots generally a half inch around the center

they arent holographic so they are not as precise

elSquid
10-06-2011, 7:02 PM
As I said, with a pistol you have a small window to keep your eye within for iron sights already anyway. With a red dot or scope, you keep the center of the reticule centered within the optic.

No one said it was easy with a pistol.


It's easy with a pistol. ;)

For the OP: I've got an RDS on a Glock, and it's pretty neat to shoot. Nice red triangle, everything in focus...it's nice for us over 40 folks. I don't find parallax to be a major concern for me. My main problem is the jerk jerking the trigger.

Anyways, red dots are used for bullseye pistol competition, so there's always that factor to consider...

( has discussion of parallax )

http://www.bullseyepistol.com/dotsight.htm

-- Michael

TATB
10-06-2011, 9:18 PM
I took an inexpensive red dot out to the range on a pistol, and the questions I'm asking now are a direct result of that experience.

The reticle could be visible outside the window if the reticle image is very close to the window (parallax-free at, say, 2"). With such "sights" you can miss the barn aiming at the gates of the barn.

With quality sights (parallax-free at infinity) and properly sighted gun inconsistent gun mounting can not shift point of impact more than 1/2 of the window width (that is about 0.5") independent of the distance to the target.
Pointing at the wall you can easily see that 0.5" shift with a naked eye, but pointing at the other side of the street you may need some optics to notice the same 0.5" shift. For most applications 0.5" accuracy is acceptable.

If you anticipate problems with proper gun mounting because of shooting from awkward positions, wearing goggles, helmets etc. you may want to have laser sights on your gun.