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Hoya 10 x 50 Extra Wide Angle binocular

Posted: Fri May 25, 2012 6:38 pm
by David Frydman
This looked interesting at under £20.
It is marked Field 7.5 degrees on the binocular.
It is the American style one piece body.
The binocular, case and strap are all in excellent condition, almost as new.
I am not sure if they are 1960s or 1970s.
They have squared off exit pupils.
The coatings are good although slightly different on each of the front O.Gs. This could be the result of cleaning the front lenses.
The binocular weighs 1010 gm
Mechanically everything is smooth.
No sign of any dust or imperfection internally, in fact as new internally and almost completely unmarked externally.
This binocular does not seem to be made by Hoya but is bought in from Yoko Sangyo or Seiwa Optical of Japan.
The prisms are caged and the collimation perfect. This seems a robust well made Japanese binocular.

The eyepiece coatings are odd, being yellow or a light gold. They remind me of the awful Asahi Pentax gold coated binoculars that were over the top and gave very blue images.
Here the coating is light and there is no colour cast.
The binocular is very sharp and surprisingly the false colour is less than with many modern medium price binoculars.
There is a lot of pincushion distortion and the field edge is poor.
However the binocular is a pleasure to use, well balanced and excellent wide field views.
The eye relief is good for an EWA binocular of this period at least if you don't wear glasses. This is not a binocular for spectacle wearers.
To see the widest field though you need your eyes close to the eye lens.

When able, I will carefully check the field size.
However, almost no modern binoculars match the field angle of EWA binoculars of decades ago.
Birdwatchers only require a 6.5 degree field and astronomers are not catered for, even though there is a need for a modern EWA binocular for astronomy especially with modern coatings.

This binocular is a pleasure to use in the daytime.
Let's see how it performs at night with expanded eye pupils.

Regards, David

Re: Hoya 10 x 50 Extra Wide Angle binocular

Posted: Sat May 26, 2012 4:55 pm
by David Frydman
The field of the Hoya 10 x 50 EWA binocular is a genuine 7.5 or 7.55 degrees with a fixed eye position.
When one considers that the 10 x 50 Minolta Standard from a decade or more later is marked as 7.8 degrees but measured at 7.6 degrees with a fixed eye position, the Hoya does well and better than nearly any present day equivalent.
The performance is better than a 10 x 50 Zeiss Jena Jenoptem and the build quality almost as good or indeed equivalent, although later Jenoptems had better coatinggs.
In addition this Hoya has very high resolution optics, better than present day binoculars, which are called High Resolution.
The Hoya was obviously assembled by skilled optical workers, unlike the modern Chinese equivalent.
Well there is no equivalent medium price binocular with such a good wide field performance.
On the Moon the contrast was a bit lower on the Earthshine compared to a better coated modern binocular, and some light is lost because of poorer coatings, but the Hoya is a joy to use.
Venus yesterday was a very crisp seemingly perfect well resolved crescent, whereas a modern binocular showed considerable flare.

Regards, David