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I'll need to add my new Prostars to the database. They are sharp, but not yet measured.

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and having now spent the evening out with several instruments, including the Nikon Prostar 7x50, I must now completely revise everything I wrote earlier.

The Nikon Prostar 7x50 has BY FAR the finest (least) edge distortion of any binocular I have ever held in my hands. And not by just a small amount, but by leaps and bounds. In fact, edge distortion seems to be nearly absent.

The best of the best that I've measured
Nikon ProStar 7x50
then
Fujinon FMT-SX 16x70
Pentax PCF WP 16x60
Nikon SE 12x50
Fujinon FMT-SX 10x70
Fujinon FMT-SX 10x50
Celestron Regal 8x42 Roof
Nikon SE 8x32
Oberwerk Mariner 7x50

In the above group, at the very edge, the finest is the Nikon ProStar 7x50, the next closest, the Nikon SE 12x50, has three times or more edge distortion.

5% to 10% in from the edge, the best, in this order, are the Nikon ProStar 7x50, then following a distant second with three to four times the distortion, the Celestron Regal 8x42 Roof, then the Nikon SE 12x50, Nikon SE 8x32, Fujinon FMT-SX 10x50. The Fujinon FMT-SX10x50 do it with an astonishing 70° Afov, the FMT-SX 16x70 with an Afov=65°. But the very fine Fujinon 10x50, at 90% out in the field, have 5 times the distortion as that measured in the Nikon Prostar.


Only the Prostar 7x50 come close to these combos
Oberwerk BT100 - 20TV pl
Oberwerk BT100 - 14 Radian
Oberwerk BT100 - 12.5 UO or

In the BT100, with the 14mm Radian at 44x, I observed a 5 arcsec double star split even as it drifted off the very edge of the field stop, a total edge aberration only 1/3rd that of the Nikon SE.

In the Nikon Prostar 7x50, I used my usual 62 arcsecond pair of stars to see where it would distort from view near the edge. It never did. I could so easily see the pair Nu Draco, even at the edge of field stop, that I would estimate total aberration at the edges perhaps only 15-20 arcsec, if that. No other fixed power binocular that I've used has ever done that. So, the Prostar gives a 7.5° field of view with distortion nearly absent, for the widest, most aberration free field of view I've ever seen in any binocular.



edz

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