Optical Hardware Ostara BM-45N Observation binocular
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1. The eyepiece fitting is 1.25" standard astro so it will accept pretty much any astro eyepiece
lens making it a very versatile instrument'
2. It utilises a triplet objective system giving better definition, colour and contrast .
3. It has a well engineered eyepiece housing, which holds the eyepieces more positively.
Uses of the BM45N are varied - Long range observation, A room with a view, Coastguard
and Law enforcement are its typical applications, but astronomers will love it too, using
standard 1.25" telescope eyepieces ( and accessories, including all the filters and the
camera adaptor etc ) it can cover so many astronomical observation requirements.
It's focal length is 560mm, so with various focal length eyepieces you can achieve varied
magnifications :
We would not suggest going below about 9 or 10mm ( above around 60x ) - and for best
long range use, magnifications of around 20x to 40x (15mm to 30mm eyepieces ) are best
... and look at what happens with a 40mm eyepiece ... you get 14x magnification - highly
significant because this gives you a 14x100 binocular - same low light performance as a
7x50 or 8x56 .... fantastic. You can get a bit of wide angle edge clipping when used at this
level but with huge light gathering and a massive magnification, this combination is incredible
( and yes , we will be launching a 40mm plossl lens into the astro eyepiece range
soon )
For moon observation you can add moon filters to the standard astro eyepieces, or indeed
any other filter to improve specific observation conditions.
We have standard eyepieces of 28mm ( giving 20x magnification ) and 14mm ( giving 40x
magnifications ) - these make it the same spec as it's predecessor, BM45 20x / 40x 100 -
and in the standard package we will include these two eyepieces so that the new model
offers the same spec. as the old one.
We would however urge you to consider selling with plossl or WA eyepieces as these
really do bring out the best in this instrument. We have some Super-wide 20mm (70field)
eyepieces in stock already ( 28x mag, an ideal mid range ) and we have a lot more focal
length eyepieces in the pipeline.
The BM45N has standard tripod fitting but should be used with a good heavy duty tripod -
From the Olivon range we would suggest Olivon 159, 189, 1250 or Olivon wooden. We
also have an Optical Hardware wooden tripod with a U-fork mount designed for the BM45,
this combination not only looks really good but is so easy to use, finding moving subjects
with a U mount is quick and tracking is smooth, and by the way the Optical Hardware
wooden tripod / U mount can be used with other instruments too and it does add a touch
of class, especially if the instrument is being sold as a centrepiece in a house with a view
eyepiece
approx magnification
9 mm 62x
10 mm 56x
12.5 mm 45x
15 mm 37x
17.5 mm 32x
20 mm 28x
21 mm 27x
25 mm 22x
30 mm 19x
32 mm 18x
40 mm 14x