Telescope Reviews: Small Binoculars- Eye Relief and TFOV vs spec

The following eye relief measurements have all been taken by focusing a translucent frosted disk attached to a caliper depth gauge. Focused at exit pupil distance, (the eye relief distance), there the exit pupil creates the smallest possible visible disk. Then measuring depth to lens, or lens recess, to find usable eye relief behind the eyepieces. Both binocular being measured and caliper are mounted to facilitate more accurate measurement.

The difference between "dist exit" and "usable ER" is the depth of the recess. Recess is important for eyeglasses weares. Little to no recess results in eyeglasses touching binocular eye lens, and that results in scracthes. A minimum recess of 3mm is good.

Usable w/cup is the ER remaining behind the fully extended eyecup.

Compare "spec ER" to "Usable ER".

The closest usable eye relief that allows me to see the entire field of view while wearing my particular thin lens eyeglasses is 13mm. Several 13mm and even one 14mm er had some very minor cut off of full field of view. All binoculars less than 13mm usable er had some fov cut off.

All fields of view have been measured on star fields.

spec*dist *rcss*usable*usable*spec*actu*
ER * exit * lens * ER *w/cup *FOV * FOV *
17 ** 20 ** 3 ** 17 ** 6 ** 5.0 ** 5.0 ** Nikon 12x50 SE
20 ** 20 ** 3 ** 17 ** 3 ** 4.2 ** 4.2 ** Pentax PCF III 12x50
16 ** 18 ** 5 ** 13 ** 3 ** 5.5 ** 5.1 ** Nikon Action Extreme 12x50
23 ** 27 ** 10 * 17 ** 9 ** 5.0 ** 5.0 ** Fujinon FMT-SX 10x70
23 ** 23 ** 2 ** 21 ** 13 * 5.3 ** 5.1 ** Oberwerk Mariner 10x60
20 ** 21 ** 8 ** 13 ** 6 ** na *** na *** Fujinon FMT-SX 10x50
18 ** 21 ** 4 ** 17 ** 7 ** 5.5 ** 5.25 * Leopold Mesa 10x50
17 ** 18 ** 5 ** 13 ** 3 ** 6.5 ** 6.1 ** Nikon Action Extreme 10x50
20 ** 18 ** 5 ** 13 ** 3 ** 5.0 ** 5.0 ** Pentax PCF WP 10x50
22 ** 19 ** 5 ** 14 ** 4 ** 6.5 ** 6.0 ** Orion Ultraview 10x50
18 ** 19 ** 6 ** 13 ** 3 ** 6.5 ** 6.4 ** Oberwerk 10x50
24 ** 18 ** 2 ** 16 ** 2 ** 6.5 ** 6.1 ** Garrett Genesis 10x50
16 ** 17 ** 5 ** 12 ** 3 ** 6.0 ** 6.2 ** Nikon Monarch ATB 10x42 Roof
22 ** 17 ** 5 ** 12 ** 4 ** 6.0 ** 6.0 ** Pentax DCFHRII 10x42 Roof
18 ** 21 ** 4 ** 17 ** 9 ** 6.3 ** 6.5 ** Bushnell Legend 8x42 Roof
20 ** 21 ** 2 ** 19 ** 9 ** 7.0 ** 6.7 ** Garrett DCF 8x42 ApoRoof
20 ** 19 ** 5 ** 14 ** 6 ** 6.0 ** 5.8 ** Oberwerk 8x42 Roof
24 ** 24 ** 3 ** 21 ** 9 ** 6.0 ** 5.7 ** Oberwerk 8x56
19 ** 20 ** 2 ** 18 ** 4 ** 8.3 ** 7.3 ** Garrett Classic 8x45
15 ** 17 ** 6 ** 11 ** 5 ** 6.5 ** 6.5 ** Fujinon BFL 8x42
20 ** 21 ** 2 ** 19 ** 7 ** 6.6 ** 6.5 ** Swift Ultralite 8x42
18 ** 15 ** 4 ** 11 ** 6 ** 6.5 ** 6.5 ** Orion Vista 8x42
18 ** 19 ** 3 ** 16 ** 9 ** 8.4 ** 8.0 ** Oberwerk Mariner 8x40
20 ** 18 ** 5 ** 13 ** 3 ** 6.3 ** 6.3 ** Pentax PCF WP II 8x40
17 ** 18 ** 4 ** 14 ** 4 ** 8.3 ** 8.1 ** Nikon Action Extreme 8x40
12 ** 13 ** 2 ** 11 ** 4 ** 8.2 ** 8.2 ** Nikon Action VII 8x40
17 ** 19 ** 5 ** 14 ** 5 ** na *** na ** Nikon SE 8x32
24 ** 27 ** 2 ** 25 ** 18 * 7.0 ** 6.3 ** Oberwerk Mariner 7x50
22 ** 21 ** 4 ** 17 ** 3 ** na *** na ** Captain's Helmsman 7x50
na ** 15 ** 5 ** 10 ** 3 ** 7.3 ** 7.2 ** Captain's Storm King 7x50
23 ** 28 ** 8 ** 20 ** 10 * 7.5 ** 7.4 ** William Optic 7x50 ED

Edited by EdZ (10/31/07 07:52 PM)

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