Before all the generations, there was a Gen 0, which was used in World War II and dates back to the 1930s. Nowadays, Gen 0 is no longer in production but, it has been replaced with the improved versions of Gen 3.
Generation 1
They were first introduced during the Vietnam War and still required some light to work properly. They were quite heavy and bulky but compared to Gen 0, significant improvements regarding image quality and brightness were made. As of now, Gen 1 devices have still kept their design but have undergone significant improvements with the latest technological advancements.
They are the best choice for those who need a more affordable option in the market but still want some of the qualities found in the higher models. Some of the limitation in Gen 1 are that the range doesn’t extend beyond 75-100 yards, whereas Gen 2 can provide a better range at 200 yard or more. Their battery lives are also shorter and have a shorter life expectancy.
Generation 2
Gen 2 improved on Gen 1, especially around the edges where Gen 1 night vision scopes would not be as bright. Gen 2 models did not require some sort of light unlike the previous generation. While most hunters use gen 1, some hunters use gen 2, which are considered to be the best option in terms of performance, quality, and resolution. Subsequently, their battery life last longer and are expected to last much longer than Gen 1 models.
Generation 3
Generation 3 is typically used by military and police as such, they are not commonly found in the commercial market for the general public. They are the highest grade but also the most costly. They offer the longest range at 300 yards or more. Their field of view as compared to the latter is significantly better. Their life expectancy lasts the longest and are more reliable out in the fields.
Just a quick note, if you encounter a night vision scope that’s labelled as Gen 4, it’s used for advertisement and there’s no real classification for Gen 4 according to the US army. They’re basically the same as Gen 3 (they’re also priced in the same range of 5k to 6k. But this is up to debate, some hunters believe that there is a Gen 4 and should be treated as it’s own category.
It’s important to not get too caught up with generations as features, specifications, and intended use are more important when shopping for a night vision scope. Solely going by generations can get quite costly and could leave you unhappy with your purchase.
In this video below, you can see the differences between Gen 1 and Gen 3.