The memory table for incandescent lighting is as follows:
Part I
1. Sensitive superpanchromatic emulsion 21 FROM;
2. One bulb;
3. Bulb 500 W;
4 Nitraphot photographic bulb;
5 Bulb-to-subject distance — 1 m;
6. Bulb in an aluminum reflector, matte without diffusing veil and without "mushroom ;
7. Iris 1 : 4;
8. Shutter or 1/s sec.
Part II
1. Changes in emulsion sensitivity (see summary 1 point of part II of the previous table).
2. Changing the number of bulbs changes the exposure in an inverse proportion. (Np. by 2 light bulbs reduce the exposure by 1 scale, at four o 2 graduations).
3. The brightness of the bulb is also inversely proportional to the exposure. (Np. next to the light bulb 1000 W will reduce the exposure by 1 scale, next to the light bulb 100 W - we will increase 5 times. In practice, about 2 graduations).
4. Light bulb - we increase the exposure by 1 scale.
5. At the distance of the bulb 1/2 m - reduce the exposure by 2 graduations.
At greater distances, the increase in exposure will be as follows:
It could make an impression, that learning by heart the data from the above tables is troublesome. However, this difficulty is only apparent. In practice, we encounter few varieties of lighting, so that it is enough to remember "every day".: shooting on 20—21° DIN emulsions —
1. On a sunny day: Iris 16 - snapshot 100 or aperture 11 - snapshot 50.
2. On a cloudy day: Iris 11 - snapshot 50 or aperture 16 - snapshot 25, finally the aperture 8 - snapshot 100
3. In a bright interior, not far from the window, aperture on a sunny day 4 - snapshot 25.
Any inaccuracies will be compensated by the emulsion tolerance.
(Aperture mark and shutter mark are given above, as it is shown on the scales of the apparatus. Of course that means, that e.g. Iris 11 corresponds to the aperture 1:11 and the snapshot 25 - snapshot 1/25 sek.
Calculating the exposure with flash lamps is very simple. Any electron tube, each flash burn lamp has the so-called. estimated number, being the product of the distance of the light source from the object in meters by the diaphragm mark (the reciprocal of the brightness of the lens).
Estimated number = meters x aperture mark
Examples:
The estimate number of our light source is 20. The object is in the distance 5 m from the lamp. Therefore:
character przysłony = 20/5 = 4
Our item, to take it in full, is in the distance 20 meters. Estimated number of lamp = 20. The largest aperture of our camera is 1 :2,8. From the calculation for the aperture mark, we get the aperture 1 : 1. To get enough exposure, we give 8 flashes (brightness 1 : 1 is eight times greater than 1 :2,8). Understandable, that the camera must then be mounted on a strong tripod.
Wanting to keep a certain aperture mark, for example 4, we find the distance by dividing the estimate by the aperture sign: 20 : 4 = 5 meters.