Kokusai Kohki Masuyama 80mm 3 inch Eyepiece

Kokusai Kohki Masuyama 80mm 3 inch eyepiece

In collaboration with Mr Masuyama of Masuyama eyepiece fame, Kokusai Kohki has gone out on a limb in introducing a truly new eyepiece, the 3 inch barrel size Masuyama 80mm. This eyepiece is aimed specifically at the many private and public owners and users of long focal length telescopes, who would like to greatly reduce the intrinsic high magnification of their telescopes while also significantly widening the FOV they are able to attain at this low magnification, gaining striking celestial views reminiscent of those seen through similar aperture dobsonian telescopes.

Although an 80mm focal length eyepiece is hardly unheard of, an 80mm eyepiece of 2 inch aperture imparts a narrow FOV that hardly gets the blood pumping, and the oohs and ahhs coming. In contrast, the 3 inch aperture Masuyama 80 goes far beyond the current 2" (50.8mm) paradigm by boldly going where few eyepieces have gone before, into the parallel universe of 3" barrel width (76mm) eyepiece design. A peculiar new universe that now allows low magnifications AND wide fields of view.

The Masuyama 80 is not a mere extension of the previous Masuyama design but a brand new design that allows it to perform with excellent image sharpness from center to edge, and little to no light loss at the field edges. Viewing through a C11 at 35X, with over 1.5 degree AFOV, this eyepiece sends long f/l telescopes into the realm of RFTs and short f/l Newtonians. With a field stop diameter of 70mm, at a 52 degree apparent FOV, the huge image combined with the amazingly lowered magnification creates a feeling of a much larger area of space being viewed that what the modest number 52 would suggest. After all, how many full moons would fit in a 1.5 degree actual field of view?

Each hand made Masuyama 80 is carefully and lovingly designed and manufactured at our factory in Tokyo. Each eyepiece is fully tested before shipment and is annointed with it`s own serial number. Production runs are limited and only 20 eyepieces are currently available for sale. Each air to glass surface is fully multi-coated. A rubber eye guard insures optimal eye positioning. And a large "tire" placed around the bottom half of the eyepiece, covered in a non-slip rubber rollet, provides a secure hand hold for the hefty 1.7 Kg (3.74 lb) weight of this massive eyepiece.

Is the Masuyama 80 a good fit for shorter focal length telescopes? Well, I would have to say that the Masuyama 80 is not for everyone, but as long as your telescope is equipped with a 3" focuser sleeve, the Masuyama 80 will provide exellent, distortion free views as well. For example, when attached to our APM 130/F6 CNC-LW telescope, the Masuyama 80 provided surprisingly clear and fresh images at the mere 9X magnification that this combination produces. No edge distortion or vignetting was seen, and images from field center to edge remained sharp and contrasty. So yes, the Masuyama will also work well with shorter focal lengths.

Now, while this was a valuable experiment, short focal length telescope owners have many other options available to get low power and wide fields without the expense (or the massive size) of the admittedly high price of the Masuyama 80. I feel that the true value of the Masuyama 80 remains with long focal length telescope users who want to gain a wide field, low power window to the universe similar to those provided by our beloved dobsonians.

To help make the transistion to a 3" focuser easier, we have also developed a low cost 3 inch star diagonal mirror system that includes the 3" adapter sleeve for easy attachment to your (larger) SCT tube`s (larger) visual back. Just screw the 3 inch sleeve on to your telescope, slide in the star diagonal, then the Masuyama 80mm. and tighten all the lock screws, and you will have instant access to a whole new universe with your long focal length telescope.

As a convenience, we also include a 3 inch to 2 inch eyepiece adapter with this set. To avoid marring or scratching, the sleeves use a wrap around band to lock your eyepiece or accessory into position.

Each eyepiece also includes its own aluminum trunk case.

The Masuyama 80 is designed and manufactured entirely in Japan. The 3 inch star diagonal mirror system is made to our specifications at our supplier in China. Quantities are limited; please contact me for availability at time of your order.