In photography, it is generally accepted that exposure is the process of irradiating with light some kind of photosensitive element in the camera. In this capacity, both the matrix (for modern devices) and the film (for film) can act.
The correct exposure setting affects how much light falls on the element - and depending on this, this or that result will be obtained. It’s important not to overdo it with exposure, since too much light will lead to an illuminated image, and too little will not allow you to draw an object - the result may be a completely dark frame.
The amount of light entering the sensing element is affected by the size of the diaphragm, the direct photosensitivity of the element itself, and exposure. This will inevitably affect the final result of the shooting.
What is exposure and overlay
Overlapping exhibits an interesting effect: an image of objects photographed at different times appears on the same frame. This technique was well known to film photographers of the old school, but with the help of modern digital cameras it is extremely difficult to implement, and exposure and combination for cheap "soap dishes" is an impossible task.
This technique can be done today in various ways:
Digital cameras
Only a few modern “numbers” have the function of superimposing two or more frames. Such devices allow you to shoot in the "green" mode, that is, in fully automatic. And in this case, you may not even have any idea what exposure is. This is also possible with the latest smartphones of the latest generation.
But even with the help of rather expensive digital “DSLRs” and, all the more, “soap dishes”, such a technique as double exposure for superimposing two or more frames in one cannot be carried out.
Film cameras
The installation of combining and exposure to film requires certain knowledge, skills and abilities from the photographer. The procedure in this case will be as follows:
the first frame is made with all the necessary parameters - shutter speed, aperture, and so on;
then the film is rolled exactly one frame back (this is not possible in all cameras);
the second picture is taken with such an aim that all the elements of the second frame exactly fall on the elements of the first. This requires an accurate eye and a lot of experience from the photographer;
an important point: in order to avoid overexposure of the film, you need to somewhat “underestimate” the second frame, setting the shutter speed a little less than under normal conditions.
Further, the film is developed and printed in the traditional way.
As an experiment, you can also simply “snap off” the entire film first, and then wind it back into the reel and shoot again. Sometimes it turns out really interesting shots.
A similar effect can also be achieved if, during photo printing, two films are placed in the machine at once - one frame will be superimposed on the other.
Software method
Finally, all of the above can be done on the computer in many graphic editors. For example, in the famous Photoshop. And for this you don’t even need to know that exposure is something that is associated with light and photocells.
The procedure will be as follows:
the first file is opened;
then by dragging and dropping in the same window opens the second file for which you want to apply the overlay;
if necessary, you can resize the second frame, rotate with special markers along the edges of the layer of the second image;
then it’s worth playing with the layer’s blending and transparency options in the layer manager on the right.
No one argues that modern software “tools” allow you to achieve high-quality and creative photographs, but it’s too early to write off the professionalism of the photographer. Sometimes well-chosen frames and extensive shooting experience create truly masterpieces.