BASIC GUIDELINES FOR PHOTO

The purpose of this page is to present simply the basic rules of photography
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THE EXPOSURE

It is the base of the photography. So that a photo is exposed well, the film or the sensor to have to receive the good quantity of light.
This quantity is measured by the photoelectric cell of the device. The quantity of necessary light reaching the film depends on three factors: the opening, the speed, the sensibility. The opening can be likened to the diameter of the pipe, the speed, in the time during which the faucet is opened and the sensibility to the volume of the bowl. It is thus possible to fill the bowl with a pipe twice as big by leaving the faucet opened twice less time... It is the base of the photography!

THE DIAPHRAGM

The choice of an diaphragm plays on the depth of field of the photo. More Le moulin de La Guierche the opening is big (more the figure is small), less the depth of field is widened. The depth of field (DOF) is the zone of neatness (of 1m in 1.50 m, for example). The choice of the diaphragm thus conditions the obtained result. To remove a face of the bottom, we choose a big opening (small figure), F2.8 for example. For a landscape, we shall can Prefer a maximum DOF, thus a small opening (big figure), F11 for example.

THE SPEED

The choice of the speed also conditions the result. For a subject in movement, a fast speed (1/1000) congeals the movement. The subject is net. With a slower speed, we see effects of Spun (impression of movement). The choice of the speed is also compulsory by the used objective. With one 300 mn, it was advisable not to use speeds lower than 1/300, with one 100 mn, 1/100... Below 1/125, it is better to use a tripod.

THE SENSIBILITY

The current dandruff have sensibilities from 25 to 3200 ISO. If you want to take photos with raised speeds (sport), a big opening, with not enough lighting, better Is worth choosing a film of 400 ISO even more. The more the figure is big, the more the sensibility is big (demand less light). On the other hand, the grain rises with the sensibility. The grain sees itself especially on one increases (30x40 and more). Certain numeric sensors propose regulations on 100, 200 or 400 and up to 3200 ISO.

THE FOCUSING

The focusing can be made automatically (autofocus ) or manually without assistant or with textured and wefts of microprisms or by means of a coupled range-finder. The focusing also intervenes on the result, at the level of the neatness, the good on, but also at the level of the depth of field. We are not going to develop the notion of hyperfocal here, but know that it is better necessary to make the focusing a little before the subject (1/3 forward) when we want to obtain the biggest zone of possible neatness in a photo of landscape.

The focal of optics influences the focusing and the depth of field a lot. A wide angle (24 mn) gives a big depth of field and thus asks for a focusing less precise than for a telephoto lens (300 mn) Which has only a restricted depth of field.

PIXELS AND SIZE OF THE IMAGE

This question is often asked and I am going to try to simplify the answer : The size of the printed image depends on two factors: the size in pixels of the image of origin and the wished resolution. Here is the magic formula which allows you to calculate the size of the image printed in cm:

Number of pixels of the image of origin / Resolution * 2.54

The resolution for a printing da argentic quality is 300 dpi. We can however come down in 180 dpi, even in 150 dpi. Down, the quality feels the effects of it sharply, except for certain types of image including few details.

For an image of 1600 x 1200 pixels (2.1 M), we obtain a printing of:

  • 13.5 x 10.2 cm for 300 dpi
  • 22.6 x 16.9 cm for 180 dpi
  • 27.1 x 20.3 cm for 150 dpi

For an image of 2048 x 1536 pixels (3.3 M), we obtain a printing of:

  • 17.3 x 13.0 cm for 300 dpi
  • 28.9 x 21.7 cm for 180 dpi
  • 34.7 x 26.0 cm for 150 dpi

For an image of 2272 x 1704 pixels (4.1 M), we obtain a printing of:

  • 19.2 x 14.4 cm for 300 dpi
  • 32.1 x 24.0 cm for 180 dpi
  • 38.5 x 28.9 cm for 150 dpi

For an image of 2560 x 1920 pixels (5.0 M), we obtain a printing of:

  • 21.7 x 16.3 cm for 300 dpi
  • 36.1 x 27.1 cm for 180 dpi
  • 43.3 x 32.5 cm for 150 dpi

For an image of 4000 x 3000 pixels (12.0 M), we obtain a printing of:

  • 33.9 x 25.4 cm for 300 dpi
  • 56.4 x 42.3 cm for 180 dpi
  • 67.7 x 50.8 cm for 150 dpi

Indeed on, it is necessary to try, according to the type of image which we have. Some will be completely acceptable in 72 dpi printed on one ink jet. On the other hand, it is more than likely that an editor can print your photos only in 300 dpi! next 

COMPOSITION

Conche des Baleines

The composition is essential in photo. It is the composition which allows to express itself, to exteriorize a printing, a feeling. The previous points concern the technique itself, the technique which it is necessary to master and Even forget to dedicate itself to a good composition... Here are some rules of composition which are only indicative but which give good results generally:

THE SUBJECT

The photo has to contain a center of unique interest. This subject must be evident. If the other elements are in the image, they must be additional of the main subject and emphasize it. An essential rule in photo and, doubtless, the most difficult to apply...

THE KEY POINTS

When one frame(executive) we always tend to position the subject in the center of the image " in the pastille! ". It is an error. The eye looks for in fact four key points of the image. Imagine two horizontal lines on your sight which share the surface in three third equals and two other lines which share the surface vertically in three third equals. The key points are situated in the intersection of these ligns.

Regle des tiers

SURFACES

The rule is identical to the key points. Surfaces are divided by third, and not by half. The horizon has to be on the third bottom or the third height of the image.

LINES

Conche des Baleines Lines, that they are realized or not, represent the architecture of the photo. They have to steer the glance towards the subject. A composition in diagonals is dynamic. A composition in parallels is static. A line can be realized by a road, a stream, lane, a street, rows of seaweeds as here. We find many lines in the nature.

THE WELL-BALANCED

The mases of the photo has to balance itself. To illustrate this concept, imagine your photo pinned to a wall by its middle. She does not have to turn either in a sense or in the other one. The dark colors "weigh" much heavier than the clear colors. It is necessary to compensate with different surfaces. Totally subjective...

OTHER IMPORTANT POINTS

  • Watch to keep the horizontal horizon. The sea which tilts, it is rare...
  • A foreground looks of the depth to an image.

  • These some rules have to be known but we can break them if we know what we make.

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