Photography Simplified

Progress, Volume VI, Issue 9, 1 July 1911, Page 733

Photography Simplified

(By Barclay Hector.)

With Notes on Pinhole Photography.

Exposure, i It is generally supposed that the exposure in pinhole photography is harder to estimate than in ordinary photography. But when it is remembered that a pinhole is equivalent to a very small-stopped lens, it will be easy to calculate the exposure. Supposing the diameter of the pinhole is l-40in., and it is being used at five inches from the plate (i.e., focal length of 5 inches), the aperture will be equal to Sin. or F. 200. And the exposure for F.-200 for any specific subject will be that found from any exposure calculator at F.-8, multiplied by about 750; the exposure, at F.-200 being abopt 750 times that required at F.-8. But it has been found that if we assign to specific sized • holes specific factors, it will be only necessary to find out the distance from the pinhole to the plate, and. multiply this distance by the factor, which will give the 1 F.-No. After finding the exposure (in seconds from a calculator, give an exposure in minutes instead of seconds. Now, the factor for the pinhole I recommend is 6. Therefore, by way of example, supposing we are using the pinhole at 8 inches from the plate, we multiply this by 6, the factor, and get F.-48. If we then find from our calculator that the exposure at F.-43 is 3 seconds, then we give 3 minutes. The following rough guide to pinhole exposure may be found useful for the purpose of first experiments:—

I also give the following list of the proportionate values of the F.-Nos., taking F.-8 as the Standard:— Exposure 8.-No. Proportionate 8 1

Continued from May Issue

Development. _ As there is an appreciable loss of definition in the image formed by a pinhole, and also the masses of light and shade being more or less merged into one another, it follows that we must use some developer which will to some extent accentuate contrasts and minimise the fog-veiling present in all pinhole negatives. I have tried various developers, and have come to the conclusion that there is none better than Pyro-Soda (Imperial Formula), but. with half as much again of the Pyro. The addition of extra Pyro tends to slow the action of the developer, but it produces greater density in the high lights, and consequently greater contrast. Do not be alarmed if, when developing your first pinhole, you, find it attains an all-over-greyish appearance, known as veiling. This is peculiar to pinhole pictures, . and will scarcely affect the resulting print. Fixing. To remove some of the fog-veiling, it is a good plan to add to each ounce of Hypo solution (4 in 20) 2 or 3 grs. of potassium femcyanide (not ferro), and after fixation is apparently complete examine the negative in daylight. If the fog-veiling is not sufficiently removed (it cannot be completely removed without ruining the negative), replace the negative in the solution for as long as it is necessary.

Suitable Subjects. Landscape. The most suitable landscape subjects for pinhole work are those in which perspective is well marked, i.e., those with strong foregrounds, well-tilled middle distances, and hazy distances. Wind is the chief bugbear in landscape work, and it is often necessary to close the aperture during a heavy gust, keeping a note of the time. In any case, the tripod legs should be firmly fixed in the ground, and it is a good plan to hang a heavy weight from below the camera. We need not be so afraid of bright sunlight as we are in lens work. That strong sunlight which in a lens photograph would give an unpleasant . stiffness, adds brilliancy to a pinhole photograph. In fact, sunlight greatly adds to the charm of a pinhole picture. It should be easy to imagine a scene where the composition and light and shade alone would form a picture without the introduction of any detail whatever; such is a very suitable pinhole subject. Another suitable landscape subject is one containing rapidly running water. It is, I think, generally imagined that running water requires a very short exposure; but it is not so. Water ripples constantly and regularly repeat themselves at certain points. Therefore, if we give a long exposure, a general average is secured which will give a most natural appearance, and a far better suggestion of movement. Still Life, Etc.— For this class of work the pinhole is pre-eminently suitable, giving, as it does, such perfect perspective

and a solidity not easily expressed with a lens. In photographing flowers with a pinhole, just so much haziness of definition is given as to make pictorial that which might be quite commonplace when taken with a lens. Let any of my readers photograph a daffodil , with a lens and with a pinhole; on comparing the two results I feel sure he will admit that the one taken with the pinhole will possess far greater pictorial quality, and will give a far truer representation than the one taken with the lens.

Copying and Enlarging.— ln copying same size, it is only necessary to place the pinhole half-way between the object to be photographed and the plate. In copying paintings and engravings the brush-marks in the former and the linemarkings in the latter will be so diffused as to be almost unnoticeable in the finished print. In enlarging, the distances'of pinhole to plate and pinhole to object can be readily ascertained from the tables given in the British Journal Almanac, and the

exposure necessary can be calculated from any meter or calculator. The following table may be useful:—

Enlarging. Reducing, and Copying

Buildings and Street Scenes. —As an unlimited angle of view can be had with a pin-hole, it follows that • the pinhole is most suitable for photographing street scenes, especially those containing tall or wide buildings. No special instructions are called for, except to remember to keep the back of the camera vertical. Great care should be taken about, this. In taking street scenes (with a long exposure), the people and vehicles passing need not be considered. If the exposure be more than three minutes the street will appear as blank as if no one had passed along it—that is, provided all the people, etc,, keep on the move for most of the time.

Portraiture.— Owing to the long exposure necessary, portraiture is not very suitable for the pinhole, but with a steady sitter in a good light, out of doors, some very fair results can be got. Using extra rapid plates, the exposures should not be any longer than were very frequently given in the days of the “wet-plate.” <■ Conclusion.

In concluding these notes, I would suggest that every artistically inclined photographer should provide himself with a pinhole, to be used as occasion demands. I feel sure that sooner or later he will find that it is not a useless part of his kit, but that at some time or another he will find a use for it, and will wonder how he has managed so long to do without it,

Subject (Middle of Summer. Bright Exposure (in Seconds), using Imperial Special Rapid Plates. Sunlight, W.P. G Pinhole) . At 5 in At Sin At 11 in At 14 in At 17 in At 20 in Open Sea - 4 9 16 27 40 57 Distant Landscape ) Open Beach jShips in Open ) 8 18 32 54 SO 114 Light Foregrounds, ) no near shadows ) 16 36 64 108 160 228 Strong Foregrounds ) Average Street [■ Scenes 1 32 72 128 216 320 456 Very heavy Fore- ) grounds - Narrow Streets j 64 144 256 432 640 912

11 .. 2 16 . . 4 22 .. S 32 . . .. 16 45 . . 32 64 .. 64 90 . . . . 128 128 .. 256 180 512 256 .. .. 1024 360 . . .. 2048

Enlargement Distance from Pinhole Relative Exposures to the Subject to the ’’late Enlargement Reduc- ■' tion Same Size ... i-oo 2'00 i-oo 1-00 Double (Half) 1'48 300 2-25 ■56 Three times 1-81 DOO 4-00 ■44 Pour times... 1-25 5-00 6-25 •39 Five times ... 1-20 6-00 9-00 •36 Six times ... 1-17 7-00 12-25 •34 Seven times 1-14 8-00 16-00 •32 Eight times 1-12 9-00 20-25 •31 Nine times... 1-11 io-oo 25-00 •30 Ten times ... 1-10 11-00 3025 ■29 Reduction to the Plate to the Subject Enlargement Reduction Distance from Pinhole Relative Exposures