Miyauchi 20x100 Binoculars
by Bill Dellinges
In May of this year I purchased a pair of 20x100mm Miyauchi binoculars from Texas Nautical Repair Co. I found Epoch Instruments of San Leandro, Ca. to offer the most generous discount as a dealer for T.N.R. I paid $3200 (list $3995) plus another $200 for the optional interchangeable 37x eyepieces. This unit has a five-element objective lens including a fluorite element (the non-fluorite model sells for about $1000 less), Bak-4 prisms, and Kellner eyepieces giving a generous eye relief of 27mm (I can just about see the entire field with the eyecups folded down wearing my glasses. The field is 2.5į (1.8į at 37x). They are fully multi-coated. Weight is 13 pounds.
I love these binoculars! Stars seem to be quite sharp near center with a slight bit of coma about halfway to the edge, not bad for f/5 binoculars. It's wonderful to pan the star fields with them and see the "big picture" after years of high power/narrow field views in telescopes. I have seen the roundness of M57 and resolved doubles down to about 13.7" (Beta Scorpii) at 20x. I also barely split Gamma Arietis at 7.6". At 37x I can see the hole in M57, belts on Jupiter, clearly resolve Saturn's rings and two moons, resolve M22 and split doubles down to 6.4" (45 Herculis). I recommend some type of viewfinder, even with the unit's 2.5į field. I have a Celestron Starpointer mounted on the binocular's handle, which works great. I can't imagine using them without it. If you were to see M24 or M7 in these babies on a dark night, I think you would be sold on them too. I'm very happy with my Miyauchis and plan to be buried with them.
Addendum to Miyauchi 20x100 review (February, 2004):
A little more than three years since my original review, the price of this binocular appears to hover around $3735, up from $3200. There is now a set of 26x eyepieces (epís) available ($335) in addition to the optional 37x eyepieces. The new 26x epís render the same field of view (2.5 degrees) as the 20x epís. Their eye relief is slightly less than the 20x and I can see only about 2/3 of the field with glasses on and the rubber cups folded down. This is still a vast improvement over the 37x epís that have the worst eye relief Iíve ever encountered. Their rubber cups are too short to fold down; your eyes must be literally pressed against the epís to see into them. It would be impossible to use these 37x epís with eyeglasses. It should be noted the Miyauchi 20x, 26x, and 37x epís are proprietary to this 20x100 binocular. That is, they have outside barrel diameters slightly larger than the standard 1.25Ē, so that other epís you may have cannot be used in this binocular.† The pictured Davis-Sanford tripod used to support the Miyauchis has been replaced by a Bogen 3051 tripod and Bogen 3433 video head, a combination I feel works well in supporting and using this large binocular (Miyauchi offers an expensive fork mount/tripod that bolts to the binocular sides).
Omitted in the original review was the fact that this 20x100 fluorite model, unlike the semi-APO non-fluorite 20x100, has extendable dew caps and interchangeable epís.† I found the individual focusing epís too easy to rotate. Even gentle contact of the eyes on them tended to defocus the image. I fixed this problem by getting - from Texas Nautical Repair - a heavier grease to apply to the inside focusing sleeves (minor disassembly of the ep housing was required-if I could do it, anyone can).† The inter-pupillary distance adjustment mechanism has the opposite problem - itís too stiff, but Iíve learned to live with it.† Nevertheless, I still stand by my original positive review: their breathe-taking views more than make up for the minor gripes noted above.