Holographic tubeless RDS

[DonP]

What exactly is considered a "real" holosight? Some links to hard data would be appreciated.

I know something about holograms and holographics - two cheap sights I have (ie not Bushnell or EOTech; a bare-bones from Belarus, and a Chinese sight) have holographic optical elements in them.

They are not illuminated with a laser (unlike an EOTech I played with) but the optical element is definately holographic. (Laser is better for illumination, but it's hardly required for the holographic part to work.)

[Drake]

They're all reflex sights, but what sets the EOTech holosight apart (Bushnell's is just a licensed copy of the EOTech) is the design - true holography.

Other RDS and reflex sights rely on a red filter to partially reflect the aiming reticule (often a red LED in most low cost models; higher end reflex sights may use light gathering fiber optics or tritium [namely Trijicon's reflex sight]) For those reflex sights with a reticule other than a dot, the light is simply reflected off a pattern first, instead of being shone directly at the filter.

The EOTech system on the other hand is designed on the same principal as the HUD in jet fighters, as explained in a previous post. It uses a laser to do this, and the laser is in front of the optics (shining towards the operator) rather than behind it as with other sights (shining in the same direction as the operator is looking).

Back when the EOTech Holosights appeared, other reflex sights were only dots, so one obvious advantage was the other-than-dot reticule. Being a real world, high end optics, it was also constructed to very high standards (including suffering from no parallax). And last but not least, since it does not use a red filter, it does not reflect red light from "the other side" (as in someone looking towards the shooter; with a reflective glass you'd see a red reflection).

On a last note about regular reflex sights (and RDS in general), the reflective glass is usually curved, and just as with camera lenses (such as wide angle lenses) the quality of the glass/lens affects image distortion. This distortion is what translate into "parallax" on sights (simply put, the dot doesnt accurately go to where it should appear when you move your head). Also, high end sights will try and reflect only the wavelength used by the dot, whereas cheaper optics will reflect a much broader portion of the red spectrum, creating the common blue-green tint when looking through a RDS (it becomes more visible as more of the red spectrum is being filtered).

[|2enegade]

wow, very informative, thx!
(p.s. of the non-EOTech, crappy RDS, which would you recommend, reflex or holo? (well.. "fake" holo anyways..))

[Drake]

They're all reflex. Even the holos. The EOTechs are "holos" cuz of the holographic technology.

For airsoft, personally I set my lower limit to the midrange cheap ones -- like the Chinese-made ones with a metal body. The cheapest ones, with a plastic body, seem too fragile and there are some very reasonably priced models made of metal that aren't much more expensive.

One of the nicer (IMO) civvy models is the ATN Reflex sight. Jackyiscxd sells some in the accessories section for pretty cheap (compared to eBay and other online sources).

The repro Aimpoints also do a good job, and there's quite a few makes to choose from. (as well as mounting options)

Like I said before, for airsoft it doesn't matter that much because your range and accuracy are extremely limited, so up close the parallax won't put you off by much, and at range your gun probably won't have the accuracy to match even if your sight is 100% parallax free.

[|2enegade]

oh wow sweet, he's in toronto...
thanks for the link!