All this talk about parallax and red dots...opinions please

[vicious]

Hey guys, I've got some questions that some of you seasoned vets may be able to help me out with. I'm wondering if there is much of a qualitative difference between red-dot sights. I'm more talking about apples to apples, not budget sights vs something like a $1400 Trigicon. Specifically looking at a Vortex Strikefire II SF-RG-501 sight (http://www.amazon.com/Vortex-Optics-SF-RG-501-Strikefire-Sight/dp/B00HYRGXOY/), a sales rep said it "auto-centers" which may or may not be bogus. In contrast my friend currently has a Primary Arms red dot (http://www.primaryarms.com/Primary-Arms-30mm-Red-Dot-p/primary-arms-30mm-red-dot.htm) and I don't have enough experience with red dots to know if the auto center is some guy trying to make a sale or a valid feature that is only available with certain red-dots. So can anyone tell me, do all red dots put the round where the dot is, regardless of where the dot is in the positioned in the tube? The second question is whether or not the Vortex Strikefire II is a qualitative improvement over the Primary Arms one...For a little over 2.5x the cost, is it at least 2.5x better?

I found an article at http://www.thenewrifleman.com/a-primer-on-ar15-optics-the-red-dot-sight/, but it didn't offer much in the way of specifics on this question. The article says, "Because quality red dots are parallax free after a certain distance, the dot can be anywhere in the viewing area and your shots will still hit the target. This is helpful when shooting from unconventional positions. The dot does not need to be centered in the glass."

However, there is no definition of what is a "quality red dot." Does quality refer to EOtech/Aimpoint/Trigicon, and everything in the budget line is not?

Thanks guys!

 

[Hump66]

Does quality refer to EOtech/Aimpoint/Trigicon, and everything in the budget line is not?

Mostly yes.

 

[dennishoddy]

I have some expensive red dots, and some bargain basement models.

The expensive, and some moderately priced models will keep the dot on target no matter where you move your head while keeping the dot on the target.

Doing the same with the cheap models, as you move your head around the dot will move all over the target. Hope this helps.

 

[uncle money bags]

All the words and all the opinions in the world will not help you until you get behind the optics in question and run them with your setup. There are major differences in the quality and consistency between cheap optics and quality optics. Whether or not those differences matter to you is solely dependent on what you need the optic to do for you, and how well you need them to perform.
Some shooters will not notice that much of a difference and while others will.
Without some idea about what you are wanting out of an optic, and how you intend to use it, it will be difficult to give you a good answer beyond what the two guys above me have stated.

 

[Rod Snell]

Strictly speaking, the dot is in the optical plane of the target (zero parallax) at only one range. However, the error effect is most pronounced if the zero parallax range is at long distance and you are shooting closer. In other words, if the parallax is preset for 100 yards and you are shooting at 20, the dot moves all over the target. It is optimum to get it set for the distance you are shooting, or at least not too much longer range. You don't have to spend a fortune, but you do need to be selective in matching your usage.
One problem with dirt cheap is that the parallax distance varies from one sample to the next, so who knows what you get.

 

[henschman]

The only info I can give you is from sights I've had... Burris TRS-25 has noticeable parallax, while Aimpoints do not.