Most of the very inexpensive consumer products today use Gen 1 technology developed nearly 40 years ago. There are three important attributes for judging performance. As the customer, you need to know about these three characteristics to determine the performance level of a night vision system. Sensitivity , or photoresponse, is the image tube's ability to detect available light. Signal plays a key role in night vision performance.
Resolution is the third major consideration when purchasing night vision.
This is the ability to resolve detail in your image. Look for the option of higher magnification so you can have it if you want it, not because your system needs it to function effectively. All you need is starlight to produce a clear image which is produced by intensification of light. As light passes through the front optical, it enters the intensifying tube which has a photocathode surface. The electrons striking the surface are amplified and projected onto a phosphors screen thus creating the image you see.