Telescope Reviews: Small binoculars - Exit Pupil & Aperture

I've only just started to measure this, but it was a real eye opener! Thought I'd share some of the first measures. Of course, eventually I'll complete the table and check as much of the magnifications as possible, although that creates other issues which I'll discuss at a later time.

Magnifications shown with 1 decimal have been measured. Exit pupil measured for every binocular on hand. See later post for discussion of small exit pupils measured.
Table mostly measured completely.

This table has been completely revised, see the later post for the updated table with verified information.
Revised Table of Data

spec * spec * spec * actu * actu * actu *
Mag * Aper * pupil * Mag * pupil * Aper *
12 ** 50 ** 4.2 ** 12 ** 4.2 ** 50 ** Nikon 12x50 SE
12 ** 50 ** 4.2 ** 12.3 * 4.1 ** 50 ** Pentax PCF III 12x50
12 ** 50 ** 4.2 ** 12 ** 4.0 ** 48 ** Nikon Action Extreme 12x50
10 ** 70 ** 7.0 ** 10 ** 6.9 ** 69 ** Fujinon FMT-SX 10x70
10 ** 60 ** 6.0 ** 10.0 * 5.4 ** 54 ** Oberwerk Mariner 10x60
10 ** 50 ** 5.0 ** 10.0 * 5.0 ** 50 ** Nikon Action Extreme 10x50
10 ** 50 ** 5.0 ** 10.0 * 5.0 ** 50 ** Pentax PCF WP 10x50
10 ** 50 ** 5.0 ** 10 ** 5.0 ** 50 ** Orion Ultraview 10x50
10 ** 50 ** 5.0 ** 10.0 * 4.6 ** 46 ** Oberwerk 10x50
10 ** 50 ** 5.0 ** 10.0 * 4.5 ** 45 ** Garrett Genesis 10x50
10 ** 42 ** 4.2 ** 10 ** 4.2 ** 42 ** Nikon Monarch 10x42 Roof
10 ** 42 ** 4.2 ** 10 ** 4.2 ** 42 ** Pentax DCFHRII 10x42 Roof
8 *** 56 ** 7.0 ** 8 *** 6.2 ** 50 ** Oberwerk 8x56
8 *** 45 ** 5.6 ** 8.2 ** 4.8 ** 39 ** Garrett Classic 8x45
8 *** 42 ** 5.3 ** 8 *** 5.2 ** 42 ** Bushnell Legend 8x42 Roof
8 *** 42 ** 5.3 ** 8 *** 5.2 ** 42 ** Garrett DCF 8x42 ApoRoof
8 *** 42 ** 5.3 ** 8.0 ** 4.2 ** 34 ** Oberwerk 8x42 Roof
8 *** 42 ** 5.3 ** 8 *** 5.0 ** 40 ** Fujinon BFL 8x42
8 *** 42 ** 5.3 ** 8 *** 5.1 ** 41 ** Swift Ultralite 8x42
8 *** 42 ** 5.3 ** 8 *** 5.2 ** 42 ** Orion Vista 8x42
8 *** 40 ** 5.0 ** 8.0 ** 4.0 ** 32 ** Oberwerk Mariner 8x40
8 *** 40 ** 5.0 ** 8.0 ** 5.0 ** 40 ** Pentax PCF WP II 8x40
8 *** 40 ** 5.0 ** 8.0 ** 4.8 ** 38 ** Nikon Action Extreme 8x40
8 *** 40 ** 5.0 ** 8.0 ** 4.7 ** 38 ** Nikon Action VII 8x40
7 *** 50 ** 7.1 ** 7.5 ** 6.1 ** 46 ** Oberwerk Mariner 7x50
7 *** 50 ** 7.1 ** 7 *** 7.2 ** 50 ** Captain's Storm King 7x50
7 *** 50 ** 7.1 ** 7 *** 7.1 ** 50 ** William Optic 7x50 ED

In both the GO10x50 and GO8x45, clearly it can be seen that one or both of the interior baffles is too small of an opening and it protrudes into the light cone path restricting aperture and therefore shrinking exit pupil. In this instance the baffle is acting like an aperture stop.

There are no interior baffles in the Ober10x50, therefore either the prism aperture is too small or the magnification is higher than specified. The Ober8x42Roof looks to have a prism aperture that is grossly too small.

Vign is % area of exit pupil blocked, in most cases by prism intruding into the light path, in some case by exposed prism edge not completely spanning the prism aperture therefore missing a portion of the light cone. All can be easily seen by looking down inside the objective barrels and by looking at the exit pupil.

I took this column out, less confusion with the primary issue.

Exit pupils were measured both lenses and several times total using a dial caliper that measures 0.02mm. I measured to the 0.1mm.

All of these are pending verification of magnification.

edz

Edited by EdZ (07/23/08 02:22 PM)

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