Al Witten Nov 4, Binoculars

Size: px

Start display at page:

Download "Al Witten Nov 4, Binoculars"

Nathaniel Berry
5 years ago
Views:

1 Al Witten Nov 4, 2009 Binoculars

2 What can you hope to see? What you need to know about Binoculars? What is best for you? How can you tests binoculars? Where can you get further informa;on?

3 Light Weight Fast to grab, easy to use, no set up Rela;vely low cost Mul;ple uses

5 M8 Lagoon Nebula + M20 Triffied Nebula + M21 Cluster Telescope view Binocular view

9 Factor Type-Optical Design Why Important Comfort, light transmission, & cost Weight Power Objective Size Exit Pupil Eye Relief Comfort & viewing stability Affect Size of view & Field of View (FOV) Amount of light => brightness and clarity Diameter of shaft of light that can enter eye How close you must get to the eyepiece Field Of View how wide & tall your view will be (ft, m, degrees) BK7 vs BaK4 Prism Affects distortion & brightness levels Anit-Reflective Coating Affects percentage of light reaching your eye

10 Types Op>cal Design Galilean opera glasses Roof prism Porro prism Image Stabilized

11 Galilean Narrow Field of View & low power Compact & inexpensive Roof prism Narrower & more compact than Porro Prisms are Silvered surface resul;ng in 12% 15% light loss Fixed prism alignment More expensive than Porro s due to design costs

12 Porro prism wider objec;ves gives beser sense of depth Wide FOV & crisp sharp image Bulkier than Roof Prism but less costly Image Stabilized Stabilizes image, eliminates low level shakes Very convenient to use Porro prism, comparable FOV, Eye Relief, & Exit Pupil Heavier than similar sized binoculars Very expensive

13 Roof-Prism Types Op>cal Design

16 Power 7 x 10 x

18 Terrestrial Viewing: 372 ft at 1000 yards or 124 m at 1000 meters Astronomical viewing: Convert to angular units, divide the view in feet by 52.4, thus 372 / 52.4 = If given in meters, then divide the view by 17.5 thus: 124 / 17.5 = 7.1 degrees

19 Field Of View FOV

21 Pupil Diameter

23 Exit Pupil = Objec;ve Diameter Power

24 Eye Relief Also known as Exit Pupil Distance The distance that the eye should be for optimum viewing. As Power goes up, Eye Relief decreases Minimum 15 mm for eyeglass wearers (17 mm for thick glasses)

26 BK 7 is Borosilicate Flint Glass Good quality but brightness falls off at edges BaK4 is Barium Crown Glass Highest quality glass High density Higher Refrac;ve Index than BK 7 Brighter & more defined image

27 BK 7 vs. BaK4 Prisms

29 At every air-to-glass surface some light is reflected back from the surface = LOST light Coatings reduce the reflection and scattering of light (glare) Uncoated Lens can lose 5% Coated lenses loose about 1.5% Multi-coated lenses reduce loss to 0.25%

30 Coated A single layer on at least one lens Fully Coated Single layer coa;ng on all air to glass surfaces Mul> Coated Mul;ple layers on at lease one lens surface Mul;ple layers on all air to glass surfaces

31 An> Reflec>ve Coa>ngs Most binoculars will have at least 12 glass surfaces. This design has 8 lenses + 2 prisms = 10 elements = 20 glass surfaces

32 Through 12 uncoated surfaces = (.95)(.95)(.95).(.95)(.95) = 54% Through 12 single an; reflec;ve coated surfaces = (.985)(.985)(.985)...(.985) = 83% Through 12 fully mul; coated surfaces = (.9975)(.9975)(.9975)...(.9975) = 97%

33 An> Reflec>ve Coa>ngs

34 Other Types Of Distor>on

35 What is best for you? Hand Held, Tri Pod Mounted, or Image Stabilize? Fully Mul; Coated Porro design with BaK4 Prisms 15 mm + Eye Relief If hand Held, between 7x50 & 10x50 Verify adequate FOV in angular degrees Verify Exit Pupil is 4 mm to 5 mm Tripod socket ¼ x 20 thread

37 Parallelogram Mount from Orion

38 How can you tests binoculars? View land object should produce a bright, clear, single circular, apparently 3D image Center star, or glint of sunlight off distant telephone insulator, and slowly move to edge of field. Should stay sharp & not become fuzzy Exit Pupil should be round, not oval, not square

39 How can you tests binoculars? Place on stable surface & focus on distant building or top of telephone pole. Back off 6 + & alternate look through one barrel then the other. Views should be aligned horizontally & VERTICALLY. (Collima;on check)

40 Further Informa>on hsp:// hsp://en.wikipedia.org/wiki/binoculars hsp://hsp:// hsp:// how binoculars work.html hsp:// hsp:// hsp:// hsp:// hsp://

41 Light Weight Fast to grab & easy to use No set up & No Alignment Large Field Of View Image is correctly orientated (U D, L R) Rela>vely low cost ($50 to $1,200) Al Witten Nov 4, 2009

ED-Lenses. Zoom. Boating. Spectator Sports. Travel & Hiking. Hunting. Mountaineering. Wildlife & Observation. Aspherical Lenses

ED-Lenses. Zoom. Boating. Spectator Sports. Travel & Hiking. Hunting. Mountaineering. Wildlife & Observation. Aspherical Lenses Aspherical Lenses Bak-4 Spectacle Wearers Eyecups Luger DIM Full Coating ED-Lenses Phase Corrected Zoom Aspherical Lenses The application of aspherical lenses leads to an accurate collimating of the light