It is also necessary that each focal point (cores and all deltas) be clearly printed in order that accurate ridge counts and tracings may be obtained.
As was previously mentioned, the camera has a fixed focus; that is, the camera will take a legible picture only when the latent print is at the focal point, or exactly flush with the opening of the camera.
The result of this is that the focal points of the impressions (the deltas or cores) do not appear.
Figures 33 to 38 reflect the focal points of a series of loops.
The diameter and focal length of a lens must depend in a great measure on the distance of the object, and also on the superficies of the plate or paper to be covered.
The outer lens is a meniscus--that is bounded by a concave and convex spherical surface which meet--having a focal length of 18 inches.
As the recognized cultural capital of continental Europe, Paris was a focal centre for visitors from many parts of the world, including the Orient.
On the slopes of Mount Carmel He erected with enormous pain and difficulty the Shrine housing the mortal remains of the martyred Báb, the focal point of the processes by which the life of our planet will gradually be organized.
It will continue to occupy this focal place in the life of the Faith throughout the coming centuries.
So unrestrained and unified an outburst of mourning reflected a sudden awareness of the loss of a Figure whose example had served as a focal centre of unity in an angry and divided land.
Sidenote: Focal Infection] It was formerly supposed that the ill effects from such conditions as dental abscess and other pus foci were wholly due to the toxins or poisonous products thrown into the blood-stream by the bacteria at the focus.
Ulcer of the stomach, sometimes caused by focal infection, 82.
Nominations and elections are focal periods in government, but government is a continuous obligation which requires constant rather than intermittent attention.
An efficient and vitalized church could advantageously be used as a focal point for the development of every phase of rural community life.
The mention of mean depth here makes us notice that the 12 miles may have been the extreme depth to which the earthquake, or shock, was felt at Charleston, and that the focal depth may have been considerably higher up than that.
Focal depths of earthquakes within reach of water, but not of lavas.
Illustration] Tybee Light had formerly been a second-class station but in reestablishing it, it was made into a first-order light, having a focal plane 150 feet above the sea.
The base of the tower was 57 feet above water and the focal plane was 86 feet above water level.
The amount by which a given telescope magnifies depends upon the focal length of the objective (or mirror) and the focal length of the eyepiece, and is equal to the ratio of these two quantities.
By reflection from this mirror the focal plane and the images are shifted to F, where they may be examined from one side through the magnifying glass E.
The distance of F from A B is called the focal length of the lens, and F itself is called the focus.
Stated in terms of the focal length they are known as F/5.
The speed of a photographic lens depends on the ratio of the effective aperture to the focal length.
Thus any two lenses used at apertures of F/8, that is at apertures having diameters one-eighth of their respectivefocal lengths, should be of the same speed, though both lenses and apertures may be very different.
Neither we, nor the day, nor the beauty of the drive had power to woo their glances from coming back to the focal point of interest they had found in each other.
In the course of the first few days we learned what all Dives had known for the past fifty years or so--that the focal point of interest in the inn was centred in Madame Le Mois.
It was provided with a well-corrected object-glass having a focal length of 200 mm.
This instrument consisted of a reflector on the "Front-view" construction, with a speculum 4 feet in diameter and of 40 feet focal length.
Founded in 1899 by Mr. Akin, entertained by Miss Monahan, this assembly has made September of each year a focal point in local interest.
They still respond to the activities which are centered in the focal neighborhood.
It may be said this would not allow of taking subjects such as a close finish of a cycle race and such like, which is quite true; did occasion arise for so doing, then a shutter such as the focal plane would be employed as a matter of course.
If the focal lengths are different, the images will be of correspondingly different sizes, and then the same detail must be compared, not the definition at the same distance from the centre.
In England a lens which will cover with a large stop, say f/8, is a desideratum, but in the Alps it is very rarely that such a large ratio of aperture to focal length is required.
If a large aperture has to be used, the focal length must be short if much depth of definition is wanted, or conversely, if the focal length must be long the aperture must be small.
By this method thefocal length of any lens can easily be determined if one has a lens of known focal length.
The distance over which the focussing screen was moved between the two focussings is to be multiplied by the length of the object and divided by the length of the image, and the result is the focal length of the lens.
The easiest way to compare the focal lengths of two lenses, is to focus both on a fairly distant object or view, and to measure in the image the distance between two fixed points in both cases.
If a lens were perfect and had a flat field, the depth of definition would depend only on the aperture and focal length.
I've got the most accurate focal point in the world.
In this case, Adrian Vance made the focal point one of my ancestors, the first Elaine Duchard.
An additional ground I have for believing it to be true is that on that mountain-side near Lhasa I had a specially favourable opportunity of looking at the world from, as it were, a proper focal distance.
And it is only from a proper focal distance that we can see what things really are.
We have a silent time-shutter built in behind the lens, and for very rapid work, such as flying bird studies, use a Thornton & Pickard focal plane shutter working up to the thousandth part of a second.
But the birds persistently avoided the pebble marking the focal plane, and clouds continually obscured the sun when I wished to make an exposure.
Eight or ten minutes afterwards there was another slip--in what part of the fault is uncertain--and this was followed at irregular intervals by many small movements gradually diminishing in frequency and in focal area.
The radius of this circle being very nearly seven miles, it follows that the resulting depth of the Woodstock focal point would be about twelve miles.
Mallet's method, as noted above, cannot be trusted to yield accurate estimates of the focal depth, or to indicate more than its order of magnitude.
Banff is likewise the central or focal point of the Canadian National Park.
Let not thy tongue pay lip service in praise of God while thy heart be not attuned to the exalted Summit of Glory, and the Focal Point of communion.
The first are lenses of large diameter and aperture compared with their short focal length.
Thus the focal point at which the rays of light converge is always regulated by the degree of curvature of the lens.
The single combinations have greaterfocal length than the double, and consequently at the same diameters larger pictures are obtainable, and they are principally used for landscape or view work.
The second class are lenses of equal diameter and aperture with those just described; but with about double their focal length, and therefore less rapid, but with more field and wider illumination; of this class are the A series.
They are of greater focal length than the double, and, on account of their simple form, are less expensive.
Section of lumbar cord showing focal degeneration and absence of cells in lateral group of left anterior horn.
In a case of fatal scurvy in an infant a "focal degeneration of the lumbar cord" has been described, extending for a distance of about a quarter of an inch (Hess).
In a recent paper the author described a focal degeneration of the lumbar cord in a case of infantile scurvy, the lesion involving mainly the anterior horn cells (Figs.
Focal Degeneration of the Lumbar Cord in a Case of Infantile Scurvy, Jour.
Hemorrhages coming about in this way should be regarded as focal complications rather than as truly scorbutic.
The little sharply lighted and heated point to which the light-rays can be brought is the focus of the lens, and the distance it lies behind the lens is called the focal distance.
The thicker the lens, or burning-glass, is in the middle, the shorter itsfocal distance, and the more strongly it will magnify.
But its most familiar and common use is in connection with some object serving as a starting point orfocal centre.
The occultist trains himself in fixing his concentrated attention upon the matter before him, so as to bring to a focal centre all of his mental forces.
In the case of Clairvoyance, we have an instance of the simplest form of astral seeing, without the necessity of the "associated object" of psychometry, or the focal point of the crystal in crystal gazing.
