about reflex sights

[Halcyon]

hmm ok, i was wondering, how do the reflex sights aim when there is only one lens? Do you line up the dot/cross with the front sight on the gun? i heard that on red dot sights, no matter from what angle you look into the scope, the dot will always be on the spot where the gun is aimed (except for angles where the tube blocks to view, of course. I meant the small slight angle differences). Is this true for reflex sights too?

Also... on Airsoft Extreme's website, there is a square reflex sight by guarder (http://www.airsoftextreme.com/acc/sm.html). On other websites though, there is a similar (if not same) one made by Walther (such as this one http://airsoftshop.polyactive.net/display.asp?ID=1534 on AirsoftShop). Is there a difference between the two? I tried asking Airsoft Extreme, but they never replied to my email =\

One last thing. What is the approximate battery life on reflex sights? I heard the real ones (except for the ones that dont use batts) can be left on for over 100 hours. How do the replicas compare to this? Thx.

[D_Man]

Ok, here is how they aim.

First off, when you look at the lens at an angle, the dot WILL APPEAR to move around on the lens, the same for red dots, due to how reflection works. However in all truth, the dot is actually hitting the same place on the lense. When you are able to center that dot on the middle of the lens, you have zeroed the sight to where it should fire. just like lining up 2 iron sight posts, here you line up the dot projected on a lens in the middle of this lens. Adjusting the sight for zeroing moves the place the dot hits the lense, changing how you look at it.

As for the similar sights made by different manufaturers, this is common. though they might have slight differences in quality and construction materials, they are based off the same design. Only those with first had expirience with these items could compare (I have none).