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Oberwerk 15x70 Binocular Review
For a while now, I have been contemplating entering into binocular astronomy and wanted a quality general-purpose binocular that I could use for astronomy as well as daytime viewing. After much research on the Internet, I decided to go with the Oberwerk 15x70 primarily because of the cost to performance ratio expressed by other owners. After a failed attempt to acquire a used pair, I decided to purchase a new unit directly from Kevin Busarow of BigBinoculars.com a division of Oberwerk Corporation. After exchanging several pleasant and helpful emails with Kevin, I placed my order and within a few days the Oberwerk 15x70 arrived!
The Oberwerk 15x70 binoculars use a pair of 70mm objective lenses for its strong light gathering abilities.
All air-to-glass surfaces are fully multi-coated to keep reflection and light scatter to a minimum. The 15x70
delivers maximum light transmission through the use of high quality BAK4 prisms and is advertised as being ideal
for astronomy. Also, this model can be collimated, if needed, by the user without having to send it back to the
manufacture/distributor. I have included a few more useful pieces of information below:
Field of view - 4.3°
Exit pupil diameter - 4.6 mm
Exit pupil distance - 15mm
Minimum focus distance - 20m
Weight - 3.3 lbs.
As someone who really believes in 'you get what you pay for', I had set my expectations at the level appropriate
for a $150 binocular when compared to other binoculars, which carry a much heavier price tag. However, don't misunderstand
me, I do not want to give the impression that I was expecting a low-quality pair of binoculars. As I opened the
box, I quickly assessed the overall quality from a mechanical and workmanship point of view. I was quite pleased.
I did not notice the complaints of other owners about easily losing focus when the oculars were disturbed. It
would appear that the manufacture is using a heavier 'stickier' lubricant, which is providing additional resistance
to prevent such focusing problems.
My review on performance is based on my sample that I received from Oberwerk Corp. Also, I have tried to report
on only the facts and keep my personal opinions to a minimum. So, here we go!
Sharpness of Optics:
In assessing the sharpness of the optics over the 4.3 degrees FOV, I folded the eyecups back to get the widest
possible FOV. Objects are quite sharp but begin to noticeably soften beginning at the outer 15-17% of FOV during
daytime use. Again, this is not uncommon with larger wide-field binoculars and even occurs with binoculars costing
over $500, albeit in some cases to a somewhat lesser degree. By unfolding the eyecups, that figure is less; however,
you are also reducing your FOV as the eyecups prevent you from getting the full FOV. Either way, the center is
indeed sharp but proper eye position is very important.
My sample showed a reasonable amount of false color around anything of high contrast that was moderately bright during daytime viewing at close range. The further away the object the less this became noticeable. The objectives are achromatic lenses and some false color is inherent by the nature of this type of glass and especially noticeable at low focal ratios and at higher magnifications. During nighttime observing, I had noticed very little false color on bright objects such as the moon, Mars, Vega, and Altair.
Mechanically, I find the 15x70 very good. The right ocular rotates with smooth and consistent resistance, as
does the focuser. The focuser wheel is large and is both rubberized and texturized for easy handling. All metal
parts are smooth and nicely finished.
I was very careful about reaching precise focus at the center of the FOV. Some minor degree of flaring on brighter
stars was noted. Also worth noting, moderate field curvature was observed beginning at the outer 20% of the FOV,
which was especially evident during daytime use.
Some of the evening objects viewed during my review of the 15x70 include: M4 - nicely visible with direct vision;
M5 - visible from my light polluted backyard; M13 - nicely visible; M57 - tiny but visible; moon - absolutely beautiful,
sharp, very little chromatic aberration around the limb, and 3D; Mars - resolved to a discernable orange-red disk;
star colors were accurate.
I am quite pleased with the overall performance of the Oberwerk 15x70 binoculars and especially enjoy the wide
FOV. Some of the high-end binoculars from Takahashi and Miyauchi offer a considerably narrower FOV, which to some
is bothersome and gives the impression of looking through a tunnel. There are several factors that make a pair
of binoculars worth buying - overall optical quality, construction, usability, and price are some that come to
mind. This is where the Oberwerk 15x70 clearly excels! Also, Kevin Busarow was a pleasure to work with. Highly