Exit pipil

[serial # 001]

For my fun and entertainment I laid out some binos and two scopes for a low light comparison on some sand bags. After focusing the bins on the deer antlers at 135 yards I decided to see what was the lowest setting I could make out the forks with the scopes. My criteria was would I shoot at the deer which carried them? The exit pupils have been included to show how irrelevant they are generally.

Tasco World Class 4-16X40 @ 7X = 5.71 exit pupil
Bushnell 6500 4 1/2-30X50 @ 5 1/2X = 9.09 " "

After this I turned them up to 8X to match the Bushnell Ultra HD 8X42 and waited.

Binnoculars Exit pupil

Minox 15X58 - 3.87mm
REI 10X32 - 3.2
Bush. 8X42 - 5.25

At 5:10 the 8X42 the scopes set on 8X were out.

Tasco on 8X = 5.00
6500 on 8X = 6.25

I turned up the scopes till I could make out the forks again.

Tasco - 14X = 2.86
6500 - 15X = 3.33

At 5:14 I had to turn up the scopes again.

Tasco - 16X - 2.5
6500 - 20X - 2.5

At 5:15 the REI 10X32 were out.

At 5:16 the Tasco and 6500 were out.

The Minox lasted until 5:20.

At this almost too late moment I wondered how the Swarovski z5 5-25X52 would fair so I ran to get it. I could not see the antlers until they were on 25X and they lasted only about a minute. The exit pupil calculates to 2.08mm. Good glass works even with this very samll exit pupil. The Bushnell 4200 4-16X40 and the z5 are equal until the 4200 gets to its limit of 16X. During the day neither are as good as the 6500 but is better during low light.

 

[watercam]

Confirming that one gets what one pays for. Would love to have had some Nikon Monarchs in the bunch but thanks for sharing!

 

[serial # 001]

The idea that one gets what one pays for is contradicted by the Busnelll 4200's being as good as the Swarovski z5. The 6500 is better than the z5 durning normal daylight hunting for about a grand less purchase price. The 4200's match the z5 until it runs out of magnification at 16X while the z5 goes to 25X. Neither are as good as the 6500 during regular hunting light for resolving detail or brightness. Both need 1X more to resolve the same detail.

The real suprise was the Tasco World Class 4-16X for under $100. I expected the Bushnell 8X42's to be better than the REI 10X32 and both scopes when they were set on 8X; but I was wrong. The REI actually amazed me; especially for a price of $132.

This was a fun excercize and suprising; except for the z5. I knew it would be very good in low light.

 

[JabaliHunter]

In low light, I have found that magnification trumps exit pupil. So for example, I can see better with a 10x compared to an 8x even though the exit pupil is smaller for the same diameter objective lens. This is the basis of the twilight factor measurement in the binocular specs. However, comparing glass at the same magnification is really illuminating (excuse the pun)!

 

[serial # 001]

JabaliHunter,

Try to convince some optics experts about that and see what happens to you over
that fact. I don't know how many times I and others have proven it at my house
with different optics. Sometimes facts are hard on some folks head.