Getting to know your camera

Something about photography and exposure..

When I was young I borrowed my dads Pentax SuperA SLR camera from time to time. I was very enthusiastic. The excitement when I went to the photostore to collect the results was the same every time… and so was the disapointment when I saw the the pictures….

I didnt know how the camera worked. If I was lucky enough to get a decent exposure, I didnt know why…and of course the pentax got the blame for every bad exposureJ

Many years later, in the digital age, it is easier, and cheaper, to practise good exposures. I started to enjoy the art of photography six years ago. Especially the histogram helped me a lot in the start. I have used a Nikon D300 camera for the last four years. Around 50 000 exposures and absolutely no tecnical problems of any kind. It makes me happy to know that I have a camera that works in almost all cases. I also have bought an underwater housing in case I want to take a bathJ

Its easy to think that good photography comes with good equipement. I don't necessarily think thats true. First of all you have to be there and press the shutter release button to make it happen. Nothing is entering the camera sensor if you dont decide to. 

What I mean is, that good pictures doesn't fly into your expensive cameraJ 

You still have to be there, compose and expose the image fairly correct to succsess.
Focusing on that instead of camera type will help more!

To make a photograph, a light sensitive metariel has to be exposed to light over a certain time. The material can be either film or a digital sensor. The sensor/film is inside the camera. A shutter conected to the shutter release button is letting the light into the sensor/film. How much light that enters the camera is depending on how long period of time the shutter is open, and how much light the aperture will let through during that time. The aperture is in the lense. It is a diaphragm of blades that can adjust the opening in the lens. The most famous diaphragm is probably the one in the James Bond intro. When James turns and shoot you, he is standing in the diaphragm..... The wider the aperture, the more light is transported through the lens and to the sensor. Exposure is therefore dependent of these two settings: Shutterspeed and aperture. Aperture is set in f-stops.

This is the normal aperture settings : 

1.4    2.0    2.8    4    5.6    8    11    16    22

The smallest f-number is the widest aperture, and the  highest number the narrowest. If you change the 

f settings from  f/4 to f/5,6 you half the amount of light sent to the sensor/film.

The shutterspeed is also set in stops:

8 seconds    4 seconds    2 seconds    1 second    1/2 second    

1/4    1/8    1/15    1/30    1/60    1/125    1/250    1/500    1/1000
You can see that 8 seconds is twice as long as 4 seconds etc.

If not enough light enters the sensor, the picture will be dark or underexposed. Shadows turns complete black and the overall look is too dark.

Some examples:

This is an underexposed image, the histogram shows clipping in the shadow area (on the left side)

To much light results in an overexposed picture. The light tones in the picture turns completely white. 

The light areas will print white.

If you use the histogram it will show clipped  highlights. (on the right side)

The last image shows a correct exposure. There is no clipped information on neither side of the histogram.

It is also possible to do the sensor more sensitive to light by adjusting the ISO levels.

The same goes for ISO levels as with shutter and apertures, its adjusted in stops.

If you adjust the ISO from 200-400, you double the sensitivity of the  sensor.

The price you pay is more digital noise in the picture.

Modern expensive SLR cameras can use extreme ISO levels and still get away with it.

Most cameras will produce noise as you raise the levels

It is still better then a blurry picture witch often is the case with  too long shutter speeds

I hope this was of some use:-)