Red Dot vs. Holographic Sights
When it comes to sighting mechanisms for weapons, red dot and holographic sights are the popular choices. The differences between the two are not readily identifiable by just a simple side by side inspection and comparison. With a red dot, or reflex sight, you have a low power LED that produces the reticle, while a holographic sight uses a more powerful laser that bounces around to produce the holographic image of the reticle. The biggest impact of this difference is the duration of the battery life for the sight. As the holographic sight consumes more power, it understandably dies quicker compared to a red dot sight. It is always recommended to turn off your sight if you do not intend to use it for some time to avoid draining the battery.
The biggest advantage that holographic sights have over red dots, is its near immunity to parallax distortion. Parallax problems with red dot sights appear when the eye is not perfectly aligned with the sight, as in this case, the line that is drawn from the eye to the reticle and beyond is no longer parallel with the barrel. This problem is more pronounced as you increase the distance between the shooter and the target. The holographic reticle in a holographic sight is able to composite for this misalignment, thereby reducing errors due to parallax distortion, even at very long distances.
When it comes to disadvantages, there are also a few besides the reduced battery life stated above. Holographic sights are a little bit more complex compared to red dots sights. Due to this, holographic sights are a bit bulkier compared to red dot sights. Then there is the slight problem of temperature. Holographic sights are not as immune to temperature variations as red dot sights. So if you are going to a location which is too hot or too cold, then it may be better to carry a red dot sight instead of a holographic sight.
Summary:
1. Red dot sights use a LED to produce the reticle, while a holographic sight bounces a LASER to produce a holographic reticle.
2. Holographic sights consume more power compared to red dot sights.
3. Holographic sights are more immune to parallax errors compared to red dot sights.
4. Holographic sights are slightly bulkier compared to red dot sights.
5. Holographic sights have a lower temperature tolerance compared to red dot sights.