Home  > English Page  > VARIOUS  > Photo
Shrewdness of Photography.

Manual Exposition

It is often useful in outside photograph to adjust manually the exposition, because the automatic mode made error sometimes. I cannot say to you how works your camera to pass in manual mode, but fair to recommend you some useful manipulation.
Certain cameras have the possibility of showing the histogram on the photograph as below. This histogram shows the sharing out of brightness on the future photograph with ongoing adjustement.

One hump Histogramm

There is in general a hump when brightness is nearly regular, typically, indoors photographs. Then in manual mode, we only center the curve of histogram in the middle of the small pink window as in example below.

Open
Here, the hisotgram is absolutely on the left: the photograph will be too dark. It is less embarrassing to touch on left side that to touch on right side. If the histogram is far from the right side, I advice to you to diminish the shutter speed.
Open
Here, the histogram is better centered, brightness will be better. But it up to you to do your own choice in term of shutter speed. Perhaps 1/45 would have been better that 1/60éme?
Open
Here, the histogram is too much on the right side, the photograph will be too clear, and perhaps zones will be "burned", namely they will saturate in the white. It is really disgusting most often, that's why I advice you to be sure that the hsitogram does not touch the right side.

Deux humps Histogramm

There are in general two humps when we make for example outside photography. From zones of landscapes are sunny, therefore clear and bright. And parties in shade have a brightness really weaker than the clear zones. Results is a curve in two humps. It is often in that case there that automatic mode of apparatuses photographs under-exposes or over-exposes the photograph. It will choose one of both humps (the light or the dark, according to chance), and it will try to center it. Then the other one humps is completely on the right (too clearly, so photograph partly burned), or completely on the left (less disastrous, but nonetheless too dark).

Then in manual mode, we improve this situation by putting one of both humps on left, and the other one on the right but without touching the right edge. It seems important to me to be always sure not to touch the right edge, in order to avoid absolutely burning zones of the photograph, what gives quickly a disastrous result.

Open
Example to do...
Open
Example to do...
Open
Example to do...

HDR : high dynamic reduction

One of the big problems of the photograph, it is: how to manage photographs with a lot contrast?
I discovered an interesting article in Competence Photo  magazine.
Here is therefore a summary and an illustration mentioned below:


Open
Pause time 30s.
We see clearly the mountain, but the resort station is over-exposes.
Open
Pause time 15s.

Open
Pause time 8s.
The mountain start to disappear, but the resort station is still over-exposes!
Open
Pause time 4s.

Open
Pause time 2s.
We have a better exposition of the station, but the the mountain has disappear, and the station center is still over-exposes.
Open
Pause time 1s.

Open
Pause time 500ms.
Here, we see clearly the resort station Les Ménuires. But we not see the landscape anymore.

Resulting photo:


Open
With a cheaper software  ( EasyHDR ), we can generate a photo by interpolation over the all other photos. The result is this photo! We see the clear and dark area, and there is no over-exposes.

To accomplish this, the only necessary thing is to have a tripod, and the software at home. Software is not expensive, and a free version is available.

Somes remark:



Created : 27 December 2008
Last update: 27 December 2008
Moostik