The twilight factor makes it possible to compare the performance of binoculars in low -light conditions. It is calculated by first multiplying the magnification by the objective lens diameter and then finding the square root of the result. In a 7x42 binocular, the twilight factor is therefore 17.2 - the minimum for sufficient detail recognition in twilight - and an 8x56 binocular has a twilight factor of 21.2. A comparison: An 8x30 binocular, on the other hand, has a twilight factor of 15.5 and is therefore less suitable for viewing in very low light conditions.
Note: The twilight factor is only one parameter among many, it does not say anything about the image quality which is a determining factor in detail recognition in twilight (twilight performance)! Twilight performance is mainly determined by as high a transmission as possible in the right spectral range, as low a straylight portion as possible, as high contrast as possible and as high a resolution as possible. Only if all these requirements are met at the same time - and only then - can the twilight factor be used a measure of the twilight performance in binocular viewing.
summan av kardemumman:
ett trubbigt verktyg som endast är apllicerbart om alla andra optiska parametrar är identiska kan jämföra optikens lämplighet i dåligt ljus.
jag tycker själv inte att det värdet tillför så mycket... alla vet att stor objektivdiameter ger mer ljus än liten med samma förstorning.