10 ENGLISH BOOKS RELATING TO «FOCAL RATIO»
Discover the use of
focal ratio in the following bibliographical selection. Books relating to
focal ratio and brief extracts from same to provide context of its use in English literature.
1
Observing and Measuring Visual Double Stars
The second edition of Observing and Measuring Visual Double Stars (2004) is the definitive book for those who are serious about this fascinating aspect of astronomy.
Focal ratio The focal ratio of a scope is the ratio of its focal length to its aperture.
For example, a scope of 250mm (-10") aperture and 1,250mm focal length has a
focal ratio of 1,250/250=5, expressed as f/5. A typical 8" (203.2mm) SCT ...
Robert Bruce Thompson, Barbara Fritchman Thompson, 2005
3
Precalculus: A Problems-Oriented Approach, Enhanced Edition
As preparation for the next example, we define two terms that are used in
describing optical systems: focal length and focal ratio. (Although we'll refer to a
parabolic reflector in the definitions, the terms are often applied to other types of ...
David Cohen, Lee Theodore, David Sklar, 2009
4
Astronomy Methods: A Physical Approach to Astronomical ...
Thus, for diffuse sources, the energy deposited per unit time onto a single pixel
depends on both the aperture and the focal length, / d\2 * Ep oc I — I (Energy per
unit time onto single pixel) (5.3) V /L / The ratio f^/d is called the focal ratio, ...
5
The Urban Astronomer's Guide: A Walking Tour of the Cosmos ...
Given the choice between a short focal length, small focal ratio scope, say, a 6-
inch f/4 (focal length 600-mm) and a 6-inch f/8 (focal length 1,200-mm) for use in
the city, I'd pick the f/8. Why? Larger telescopes are not handicapped by bright
city ...
6
Astronomy: A Physical Perspective
We adjust the focal ratio in a camera by changing /-stops. Since the focal length
of the lens is fixed, we change the focal ratio by changing the diameter of a
diaphragm that controls the fraction of the total lens diameter that is actually used.
7
One-Shot Color Astronomical Imaging: In Less Time, For Less ...
A telescope with a fast focal ratio can image in just about any kind of seeing
conditions. The faster lightgathering ability also makes it easier for your mount to
track your targeted object, since shorter exposures are able to be used for the
same ...
8
The Principles of Astronomical Telescope Design
Figure 6.12 shows the half extending angle from the focus to the reflector edge
and space loss to reflector edge as functions of the reflector focal ratio. The
extending angle decreases while the focal ratio increases. For radio telescopes,
the ...
9
Planetary Nebulae and How to Observe Them
Then the focal ratio must be worked out, which can be done with the following
equation: Fr=[(C/E)–1]T where Fr is the focal ratio, C is the focal length of the
camera lens, E is the focal length ofthe eyepiece and T is the focal ratio of the ...
10
Introduction to Astronomical Spectroscopy
This relation contains the inverse of the focal ratio or f -number fT /DT of the
telescope. Thus, an ideal fiber conserves the focal ratio of the input beam. Total
internal reflection is known to occur only when the angle or to the fiber axis meets
the ...
10 NEWS ITEMS WHICH INCLUDE THE TERM «FOCAL RATIO»
Find out what the national and international press are talking about and how the term
focal ratio is used in the context of the following news items.
Orion SkyQuest XX12g Dobsonian
... perhaps for some little evidence of the coma expected of this focal ratio. My corrector lens easily brought these peripheral sluggards into line. «Astronomy Now Online, Apr 15»
iStar WXT 204-6LT refractor review
Focal ratio: f/6. Weight: 14.7kg (32.4lb) including rings and focuser. Tube length: 97.7cm (dew shield retracted) Price: £3,225 (with two-inch ... «Astronomy Now Online, Mar 15»
Celestron NexStar Evolution 9.25 review
Its primary mirror has a larger focal ratio than other models, so the secondary magnification factor is less, resulting in a flatter field which is a ... «Astronomy Now Online, Feb 15»
Here's Dawn's Best View of Ceres Yet
... and volume and cost constraints, the “Framing Camera” has an aperture of just 20 mm in diameter, shy of one inch and the focal ratio is F/7.9. «Universe Today, Jan 15»
Grinding glass at the Steward Mirror Lab in Tucson, Arizona
The VATT has an extremely fast focal ratio of f/1.0, which is appropriate for wide field surveys. Since then, the Tucson Mirror lab has developed ... «Canada.com, Dec 14»
New telescope provides students a never-before-seen view from …
The aperture with a focal ratio approximate to six has the capacity to capture more light, creating a brighter and clearer picture. “With this ... «FIUSM, Nov 14»
How to master street photography
... which allows you to control the aperture (usually specified as an "f-number", the "f" standing for focal ratio), ISO and shutter speed. Aperture is ... «GQ.com, Nov 14»
Canon PowerShot G16 with 12.1-megapixel CMOS sensor …
The lens has a focal ratio of f/1.8 (Wide) - f/2.8 (Tele) which should enable it to perform well under low lighting conditions and for creating soft ... «NDTV, Jan 14»
Deerfield business makes professional telescopes
That telescope has a 6.5 focal ratio, which gives it a circular field of view of almost 1 degree of the sky, Iott said. From horizon to horizon, the sky ... «The Daily Telegram, Nov 13»
New olloclip 2X Telephoto for iPhone: Glass Beats Software
The large aperture of the objective lens is required, by optical design, to maintain the effective focal ratio of the iPhone's camera lens. Because ... «The Mac Observer, Jul 13»
