Parallax in a red-dot scope?

[TMan]

I'm assuming you all know what parrallax is in a regular scope. If you don't try this with a scope that doesn't have adjustable objective. Look at a target 25 yards away; move your heard around . Notice how the cross-hairs move on the target? That is parrallax. It is noticable at 25 yards because your scope is set to be parrallax free at 100 yards (unless it is a rimfire scope).

I 'borrowed' a red dot to mount on my Sig Sauer 522, which I mounted this evening. I'm not a big red-dot fan, but I've been told that part of my problems have been because of me focusing on the target instead of the red-dot.

So, with the scope mounted on the 522, I lokked through it and found that if I moved my head around in a rotation, that the red-dot moved on teh target. Has anyone else discovered this?

[MLB]

I'll try it out with the red-dot I have on the RMII this weekend. Can't do it tonight; One of the kids has a friend over for the night. Don't need them going home with stories of me pointing handguns around in the house...

[TMan]

Now that Sig Sauer is back in my graces, I tried out a 522 w/Sig Red-Dot scope on it today. I glued my cheek to the stock so I would be looking through the scope the same way. After zeroing it in, it performed very well except one group that was way off. Apparently I did something wrong with those 5 shots. They were fairly close together, but way off from the point of aim.

I don't have a red-dot on a pistol, but I've heard some people talk about the quality of certain red-dot scopes. The Sig is not a real expensive red-dot, as I recall, it was around $150.

I've tried 2x and 4x scopes on handguns with dismal results.

[5ontarget]

I've used the 1x/holo type red dots, and, yes there is indeed paralax. A good solid and consistent cheek weld was needed to help eliminate the problem. I have also use the iron sights as a double check from time to time just to make sure what I'm pointing the red dot at is the same as the muzzle.

[TMan]

OK, so I don't have my head up my... (for once).

Just suppose you took a red pepper and cut out a small round piece. Then you used a wire that was so small that it was virtually invisible and mounted the pepper toward the end of your handgun. Then looking at the target you see the red-dot pepper in the middle of the target. See where I'm going with this?

Now take a pistol, remove the rear sight, and move the front sight close to where the rear sight once was. Paint the front sight red.

I think we have previously established that the further the front sight is from the rear sight, the greater accuracy we will have in shooting the handgun.

With our modified handgun, there is only one sight - that red-dot sight with zero sight radius. Why has our accuracy suffered?

I once mentioned to a gentleman at the range, who has shot at Camp Perry in the past, that I never shot well with a red-dot or a scope on a handgun. He told me that you have to focus on the red-dot or cross-hairs and not at the target.

With normal front and rear sights there is alignment between the center of the target, front-sight, rear-sight, and eyeball. With a red-dot sight there is front sight, red-dot, and eyeball. Am I missing something here? Is it a basic difference in physics?

Does the length of the red-dot tube matter? Suppose you have a long tube and there is something in the front of the tube that projects a dot at the back of the tube. Does this give you better precision than a short tube? i.e. does the length of the active elements in effect produce a sight radius?

How does the alignment of the eyeball with the rear of the red-dot ensure consistent accurate shots? I think 5OT's observations with a good consistent cheek-weld are right on target (excuse the pun). How do you effect this alignment in a handgun?

Am I way off base in my pondering? If so join me in some cognac (since we are friends with the French again).

[5ontarget]

I've thought of this as well, the idea of one point to establish the plane of the barrel to the target, vs using 2 with iron sights. But isn't a traditional scope reticle essentially the same thing?
A longer tube could decrease some paralax by decreasing your overall field of view.
As you know, the quality of all optics vary, and is often strongly corelated to price. I tired a number of the $50-100 varieties of red dots, but they were not bright enough for me, or their color was not good for my colorblindness. I could not see them on a mostly sunny/sunny day. (yes, I turned up the brightness to max) Even at gunshows, I struggled to see the red dot on a couple models. I thought a dealer was pulling my leg when he was demo'ing his red dot and all the various shapes he could make his reticle. I couldn't see a thing through it, I just nodded and smiled.
So knowing that, perhaps I'm not the best person to be puting input here I do see the dot nicely through my current red dot though...
www.midwayusa.com/viewproduct/?productnumber=453878

Prices seem to be up since I bought mine.
odd, it is advertised as paralax free. Maybe I should read up more on paralax before I start trying to talk with boot leather in my mouth.

[TMan]

Probably parallax is not the right term to use to describe what I'm talking about here. However, the effect is the same: the POI changes in relationship to your eye location.

When we have a scope, there is a front lens and a rear lens, and they are some distance apart and parallel to the bore of the gun. Once parallax is eliminated, putting the cross-hairs on the target gives you good accuracy.

Friday there was a guy at the range shooting a Ruger Mark III with a red-dot on it. At first I thought it was a handgun scope, but then I noticed the battery. It looked all the world like a scope because of the long length. Perhaps that has something to do with it. However, the EOtech that you have the link to is a holographic sight, and they have a great reputation for accuracy.

I just have this nagging feeling that I'm missing something in my understanding on how these things work.

[MLB]

I have an Aimshot 5100 (http://www.inovatech.co.uk/shop/product.php?productid=101&cat=0&page=1). It's a cheaper red dot reflex. I don't think it's available anymore.

Sighting on a nearby target, I kept the handgun steady while moving my noggin. I noticed that while the red dot moves with my head, it moves to stay at POA (as my perspective changes) as long as I don't move too far towards the edge of the glass. Than it moves off target.

I'd imagine that there is some small amount of parallax even when the dot is close to the center of the glass, but it gets exponentially bigger as you start sighting at the edge.

[TMan]

Am I doing something wrong, or is it just that this is a cheap red-dot. It has been sitting on the desk-top for a long while, and I thought I'd mount it on a rifle, but got to playing with it first.

With it sitting on the desk-top, I have it aimed at the door jam, which is about 10 feet away. If I move my head just a litle to the left or right, the dot moves on the door jam. I can understand that like MLB experienced, if you are at the extremes of the field of view, there could be differences, but I'm not moving my head very far.

Becky has a Sig Sauer red-dot in stock that says "Parallax Free" (maybe parallax is the right term for a red-dot). I'll pick it up later in the week and see how it behaves. I remember buying an Ecotech at one time, but I have no idea where it is, probably on some gun buried in a safe somewhere.

I just went upstairs and checked. The one I'm looking through is made by BSA - who isn't too high on my quality list. Wonder if Mueller makes a red-dot? I'll be back...

I'm back, and I found another red-dot, but it too is a BSA. The first one was a RD30 and this is a PMRS. I went to their web-site to look up the specifications and you will not believe what I found:

SPECIFICATIONS
Magnification 1X
Obj. Lens Diameter (mm) 30
Exit Pupil Range (mm) 30
Field of View @100 Yds 68
Optimum Eye Relief (in) UNLIMITED
Parallax Setting 50 yds.
Click Adjustment Value 1/2
Adjustment Range 45 - 45
Transmission(%) Day/Night
Weight (ounces) 5.00

Anyone notice about half-way down the list "Parallax Setting 50 yds". I've been had!!!!! $%^&#*@ I should know better than buy cheap stuff - life is too short. I'm not going to buy a $1000 red-dot to put on a $200 rifle, but I need things that are at least a decent quality.

I'll slap this BSA on a rifle that I know shoot well, and give it a try at 50 yards.