Optical Tech Talk

APM MS binoculars for universal application

The Optics:
ED-APO binoculars, regardless of their magnification or aperture, use high-quality ED glass (FK6l) and BAK-4 prisms for high contrast and sharp images across the entire field. Special coatings on all optical surfaces further enhance the image quality and ensure true-to-life colors. You can see e.g. even the finest details in the plumage of birds or in the stadium from the upper ranks.

The Housing
ED-APO binoculars have a magnesium housing, the lightest of all metals. Magnesium is furthermore known for its sturdiness and its resistance to corrosion. The binoculars are also covered with a rubber coating, which protects the binoculars further and allows a safe, non-slip grip without weighing too much. All binoculars are filled with nitrogen, this prevents on the one hand the fogging from in- side, and on the other hand guards against contaminations such as from lens fungus etc.

APM Telescopes ED-APO binoculars are of course water-resistant, so you do not have to worry if your binoculars get wet. if it gets wet, just let it dry at home and it is ready for use again.

Comfortable View
ED APO binoculars have a comfortable eye relief of l6 mm to 23mm. The term eye relief explains where you have to place your eye to survey the entire field of view. The smaller this distance, the closer you have to bring your eye to the eyepiece. if you wear glasses and want to watch with them, this distance becomes very important.
Since the ED-APO binoculars have a large eye relief, you can oversee the entire field of view even with your glasses on.

Apo: Apochromatic telescope or binoculars; instrument with perfect color rendition

Resolution: Smallest separable angle for given lens diameter

Eye relief: The distance between eye and the last surface of an eyepiece within which the user‘s eye can oversee the full field of view

Exit pupil: Diameter of the light beam emerging from the eyepiece; results from the ratio of lens diameter and magnification

BaK-4: Barium crown glass; optical glass for the production of higher quality glassware Refractive index: determines how much the path of light is bent, or refracted, when entering a material Focal length: Distance between the main plane of an optical lens or lens system and the focus

Roof prism: Prism for deflecting the beam path with right-sided but inverted image

ED glass: Stands for extra-low dispersion glass and describes special lenses that significantly reduce the chromatic aberration

Flint glass: Optical glass with higher refractive index than crown glass

Objective: Entrance pupil of an optical instrument; either a lens or a mirror

Focal ratio: Ratio of lens diameter of objective to focal length of objective; inverse figure is aperture

Eyepiece: The telescope objective creates an image near the focus, which is magnified by the eyepiece and becomes visible for the eye.

Porro prism: reflection prism that produces a righbsided, upright image rms: Measure of the deviation of an optical surface from the ideal shape

5D glass: Stands for special dispersion glass and describes special lenses that significantly reduce the chromatic aberration Semi apochromat: Semiapochromats have a slightly worse color correction than apochrornatic ones.

Strehl: Measure of the quality of optical instruments; a perfect optics has a Strehl value of 100%, Strehl values of more than 80% are described as diffraction limited

Magnification: Ratio of focal length of objective lens to focal length of eyepiece

Coating: Coating of optical surfaces to reduce reflections,