Assertion: eyepiece's length | /r/HasProperty | focal
Facets:
value: shorter
type: DEGREE
Source sentences:
text: Commonly available eyepieces have focal lengths between 6mm and 40mm.
text: If the magnification is kept the same (i.e., the eyepieces have the same focal length), an eyepiece with a wider apparent field will have a wider true field.
text: When images are examined in the microscope, an intermediate image (see Image Plane (3) in the tutorial window) is formed by the objective at a distance a, which is slightly closer to the eyepiece than its front focal length, F'(e).
text: The eyepieces are plossl design and come in 5 focal lengths, 6,8,13,17 and 32mm.
text: Eyepieces have focal lengths, too —
text: Eyepieces also have focal length, which lets you know the magnification the eyepiece offers you.
text: An eyepiece is defined by its focal length, apparent field of view, and barrel size, but how do you know whether it's right for your telescope?
text: An eyepiece is usually described by barrel diameter and focal length.
text: Eyepieces and telescopes are denoted by their focal lengths.
text: To achieve longer focal lengths, the eyepieces would have to be huge.
text: The eyepiece has a focal length indicated in millimeters.
text: Eyepieces usually have their focal length marked on the piece.
text: The eyepieces are referred to by their focal length.
text: Ideally, both eyepieces should be of the same design and focal length and come from the same manufacturer.
text: Here are the eyepiece focal lengths for different focal ratios and exit pupils.
text: Perhaps the most important specification of an eyepiece is its focal length.
text: An eyepiece is defined by its focal length, apparent field of view, and barrel size, but how do you know whether it's right for your telescope?
text: As I explain in my article on calculating magnification, each eyepiece can give a different magnification based on its focal length.
text: The distance between the eyepiece and the objective lens is made slightly less than the sum of their focal lengths so that the first image is closer to the eyepiece than its focal length.
text: To determine the magnification of an eyepiece, divide its focal length into the focal length of the telescope’s objective lens or mirror.
text: The eyepieces are referred to by their focal length.
text: An eyepiece is essentially a combination of lenses used as a magnifier, the latter being a positive lens of short focal length that forms a magnified virtual image of the object placed at a distance from the lens less than its focal length.
text: For instance, let’s say you have two eyepieces, and their focal lengths are 25 mm and 10 mm.
text: The eyepiece is placed so that the first image is closer to it than its focal length
text: This places the first image closer to the eyepiece than its focal length, so that the eyepiece will form a case 2 image as shown in the figure.
text: Many eyepieces have an eye relief (distance of exit pupil from eye lens) that is directly related to its focal length.
text: Incidentally, notice how I characterize the scope and the eyepiece... the scope by its diameter and f-ratio, the eyepiece by its focal length.
text: The magnification of the eyepiece depends upon its focal length f e f_{e} and is calculated by the same equation as that of a magnifying glass (above).
text: High magnification power eyepieces have a shorter focal length while those with low magnification power have longer focal lengths.
text: Removable eyepieces have fixed focal lengths, and they need to be re-focused each time you set them on your telescope.
text: The figure illustrates the basic properties of a telescope eyepiece: focal length, field of view (directly determined by its field stop size), exit pupil and eye relief.
text: We think of them as Plössls that just happen to have 20mm of eye relief regardless of their focal lengths.
text: In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio.