Ads
related to: magnification of a telescope formula
Search results
Results from the WOW.Com Content Network
For a good quality telescope operating in good atmospheric conditions, the maximum usable magnification is limited by diffraction. In practice it is considered to be 2× the aperture in millimetres or 50× the aperture in inches; so, a 60 mm diameter telescope has a maximum usable magnification of 120×.
where λ is the wavelength of the observed radiation, and D is the diameter of the telescope's objective. The resulting R is in radians . For example, in the case of yellow light with a wavelength of 580 nm , for a resolution of 0.1 arc second, we need D=1.2 m.
To find what eyepiece is required to get minimum magnification one can rearrange the magnification formula, where it is now the division of the telescope's focal length over the minimum magnification: =. An eyepiece of 35 mm is a non-standard size and would not be purchasable; in this scenario to achieve 100% one would require a standard ...
where N is the uncorrected f-number, NA i is the image-space numerical aperture of the lens, | | is the absolute value of the lens's magnification for an object a particular distance away, and P is the pupil magnification. Since the pupil magnification is seldom known it is often assumed to be 1, which is the correct value for all symmetric lenses.
Magnification increases, therefore, when the focal length of the eyepiece is shorter or the focal length of the objective is longer. For example, a 25 mm eyepiece in a telescope with a 1200 mm focal length would magnify objects 48 times. A 4 mm eyepiece in the same telescope would magnify 300 times.
Crumey obtained a formula for as a function of the sky surface brightness, telescope magnification, observer's eye pupil diameter and other parameters including the personal factor discussed above. Choosing parameter values thought typical of normal dark-site observations (e.g. eye pupil 0.7cm and F = 2 {\displaystyle F=2} ) he found N = 7.69 ...
Visulization of flux through differential area and solid angle. As always ^ is the unit normal to the incident surface A, = ^, and ^ is a unit vector in the direction of incident flux on the area element, θ is the angle between them.
For example, a 10 × 42 binocular has a 4.2 mm wide exit cone, and fairly comfortable for general use, whereas doubling the magnification with a zoom feature to 20 × results in a much more critical 2.1 mm exit cone. Optics showing eye relief and exit pupil 1 Real image 2 Field diaphragm 3 Eye relief 4 Exit pupil
Ads
related to: magnification of a telescope formula