First of all we need to understand that "Night Vision" is intended to enable us to see in the dark, not to be a long range observation system as with telescopes and binoculars etc.
Certainly as the technology advances we are able to see greater distances than in the past, and are able benefit from it all.
OK, now let us look at what various types of night vision will give us.
Thermal imaging detects the heat of all objects, living or not, you need no light at all.
Obviously the greater the temperature difference, the greater one object will stand out from other surrounding objects. For example, on a hot day in the "field", a small animal will not be easy to see against the surrounding hot ground, rocks etc. whereas at night in the same location it will stand out clearly.
But let’s think about that for a moment, why would you need thermal or any other night vision system in the daylight anyway?
A "live target" among rocks etc. that are a similar size, and are still hot from the days sun, can be a little hard to distinguish until the rocks have cooled somewhat, therefore providing a greater temperature difference between them and the target.
Naturally enough a moving target will be obvious. (Rocks do not normally move !)
Other forms of night vision, image intensifying, including digital, ALL require some LIGHT, whether it is the ambient light generated by stars, moon or an external infrared light source, as they amplify any available light. Although the night is never TOTALLY dark, it will require at least high end Gen 2,e.g. 2+ or Gen 2 HPT, and preferably Gen 3 if there is no moonlight available or an external IR light source to provide a usable image.
Digital equipment is a usable option for limited use due to the improvement of these items, coupled with the price comparison with other forms of night vision, makes them a possibility. Some of the current models of digital night vision rifle scopes compare reasonably favourably with Gen 2 image intensifying night vision. Although digital items still require large amounts of additional Infrared light to obtain any sort of distance recognition. Digital units are also not affected by bright light / daylight should they be turned on in those situations, whereas lower end varieties of image intensifying night vision gear can be damaged by that occurring.
The general consensus is that Image Intensifying units will provide more detail or definition of the target when compared with most thermal imaging, this is an interpretation view point only, but regardless, will still NOT see a "desired" target in dark shadows, whereas thermal will make these stand out and be seen without question.
The higher specification models of thermal imaging can provide the user with outstanding detail giving the best of both worlds.
There are units combining thermal and image intensifying NV, but they are unfortunately out of reach to the general "public", as are the new High Spec thermal products.
Do not expect to get the same performance from a $300 NV item that you will get from one costing $30,000!
THIS IN NO WAY IMPLIES THAT ONLY TOP END UNITS SHOULD BE CONSIDERED.
Whatever produces the desired results and is within a budget is obviously the choice to make.
If you intend to make observations, for example, from inside a motor vehicle or inside a building, thermal imaging will not "see" through glass windows, while image intensifying can be used but with somewhat reduced performance.
When making a choice of a system type to use, remember that any type night vision other than thermal, will have difficulty when trying to observe something or someone when they are even partially covered or concealed behind bushes. The use of infrared illumination will only provide limited benefit when used in an attempt to light up the bushes. All that will be seen is the I.R. glare reflected of the face of the bush, just as that observed when using a spotlight in the same situation.
Having said that, a "hot" target completely covered by an object which prevents any heat being radiated, will not be seen with thermal imaging either.
Various "generations" of image intensifying night vision exist, these nominally start at Gen1, there is also mention of Gen 0 at times, and go up to Gen 3, plus various "improvements" after that. Generation 4 * is also referred to at times but it is not an official classification. The Generations relate to changes in design and their performance in low light conditions, and at the same time image quality improves accordingly. The greater number of line pairs per mm (lp / mm) the better the image resolution produced but will not substantially increase the detection distance . Prices naturally increase relative to their performance.
It is important to be aware of just what the differences actually are. Unfortunately it is difficult to explain all this in text. It is always beneficial to discuss this in detail with us prior to making a decision what may be applicable for the job at hand.
One difference between types of night vision systems that may influence selection for a shooter, is that with the use of I.R. illumination with image intensifying units, "eye shine" can be detected. Thermal imaging will not produce this effect, as no illumination is required, therefore there is nothing to be reflected back to the shooter.
An example situation to consider for instance, even a medium sized animal in a “clear” paddock with long but not excessively so, grass, at 100 – 200 M thermal imaging will clearly indicate a “target” is there, even partially obscured by the thick grass, and although you may not see enough of it above the grass to properly identify what it is, you will know it is there.
Changing from thermal to image intensifying NV, even Gen 3, the "target" will tend to blend into the shadows and shapes in the grass and be difficult to even see, although it is widely accepted that this type of equipment will (supposedly) provide better definition of the target than thermal.
* Photonis have now released a "G4" tube (not "Gen 4") which has some improved specifications. Basically the improvement is better signal to noise ratio and a slight improvement to average lp / mm. There is also slight improvement to the EBI. Unfortunately the light amplification is still reasonably low compared to current Gen 3 tubes. In my opinion it will not provide a casual user any real benefit for the extra money.
A classic example of how thermal will show up a target that may otherwise be missed with a quick scan of the surroundings.
Just imagine how difficult it would be if the man was even just into the edge of the trees.
By arrangement, AUSTRALIAN SHOOTING SERVICES can arrange night demonstrations of all grades of night vision and thermal imaging equipment in most areas.
Should you choose to go down the path of using thermal for "spotting" and image intensifying for shooting, you will not overcome the problem of knowing something is there alright but you probably will not see it to shoot it.
These are just a few of the things that you need be aware of when choosing your NV type and models.
Again it is important to really consider how you wish to operate in your situation and not be told by others what you need, just be aware of the differences.
THERMAL IMAGING OR IMAGE INTENSIFYING?
Photo courtesy "Guns America"