Zeiss FL Diavari 6-24 56mm versus 72mm

[dogfox]

Hi,

Has anyone had chance to compare side by side the Zeiss FL Diavari 6-24 56mm versus 72mm in the last few minutes of light, which is the important bit where it matters.

Forgetting the 1 cm adjustments, turrets getting it mounted etc., its those last few minutes of light that matters. Is there much difference and is worth the extra money.

Dogfox

 

[MudRunner2005]

Man, 56mm is really all you need.....To me, 72mm is just rediculously big.

 

[dogfox]

Its about those last few minutes of light, and is the 72mm much better, does it give you an extra 10 to 15 light of shootable light to get that fox killing your chickens.

Dogfox

 

[Svein Lerbrekk]

I have two 6-24x56 and one 6-24x72 and the 72 gives you an egde over the 56 in low light conditions.

 

[dogfox]

I have two 6-24x56 and one 6-24x72 and the 72 gives you an egde over the 56 in low light conditions.

Hi Svein thanks for response, just out of interest are you able to quantify the difference between the two in low light conditions.

G

 

[Svein Lerbrekk]

The 72 will give you around 15 minutes more on a dark night, but on a low light night it will give you the possibility to hunt all night, I use a rubber pice (home made) to keep out the stray light and that helps a lot.

 

[bruce_ventura]

The answer depends somewhat on the hunter's age. The eye pupil dilates to a smaller size for people above the age of 50. Someone in his sixties will probably have 5-6 mm pupils in low light.

For some one with 6 mm pupils, both scopes will have the same brightness as the naked eye up to about 9.3 magnification. Above 9.3 the 56 mm scope will start to loose brightness. The 72 mm scope will have the same brightness up to 12 mag, above which it will also start to loose brightness. By comparison, a 40 mm scope starts to loose brightness at 6.7 mag.

In low light the human vision system trades off resolution against contrast. Higher magnification is like having higher contrast. In low light, contrast is what determines how well objects can be seen. The 40 mm scope allows someone with 6 mm pupils to see 6.7 times better than the naked eye, the 56 mm scope is 9.3 times better, and the 72 mm scope is 12 times better. "Better" can mean either higher contrast at a constant resolution (or range) or higher resolution (or range) at a constant contrast.

The phase of the moon, weather, terrain and vegetation are factors too. A quarter moon provides more light than clear starlight, which provides more light than overcast starlight. A flat prairie grassland provides more light than a tall forest at the bottom of a canyon.

 

[dogfox]

Many thanks Bruce for that in sight into the benefits from the larger object lens. That slightly brighter image with a little extra magnification will be a real help.

G