Correctly exposed photos

Taking good photos - learning photography

Aspects for a good photo: technically perfect, artistically meaningful, personal memo value.

Everybody wants to take good pictures - but what are the characteristics of a good photo?

There are distinct aspects:

1. technically good photos (This chapter and following one)
2. artistic valueable photos (Chapter about image composition, etc.)
3. personal memorable photos (with memo value, often only for the affected persons :))

There is a nice and pretty old German quote: „Vor der Kunst kommt das Handwerk“ translated this means "Prior art, craft comes". It is extremly helpful to understand the craft and the tools to appropriately use them. Particularly, their limitations.

The good news is: Everbody can learn photography. It is mainly understanding of the technical aspects and correlations, knowledge that cannot be avoided when wanting to take high quality pictures. I do not speak of snap shots or the typical party and christmas photos. The aim of this photo course is, that afterwards you are able to take a photo with the outcome you desired. Away from random strokes of luck to wanted and skillful photos.

Hence, the first steps are the technical aspects of a good photo.

What do we understand as a good technical photo?

1. The Sharpness/Blurriness is as desired (Blurriness can direct the view of the observer).
2. The colours match (no accidental and improper color cast).
3. The contrast range is used (no lifeless pictures, if not desired).
4. The illumination is appropriate.

Contrasts are directly correlated with a correctly exposed photo. That is, why we directly start with the correctly exposed photo.

Elements of a correctly exposed photo

There are two important aspects of correctly exposed photos:

Aperture and time.

For an easier understanding imagine water and a vessel instead of light and film viz. image sensor. The amount of water varies through opening and closing the tap. What the tap is for water is the light for the aperture opening. This one can also be opened and closed. The vessel collects the water - as in photography the image sensors collects the light. When I have a vessel I want it filled completely - equally the image sensors needs a specific amount of light for a correctly exposed photo.

Thereby there are three things that can be adjusted:

• the vessel, which collects the water (that is the equivalent to the image sensor of the camera)
• the tap/ faucet, to regulate the amount of water (the aperture in photography)
• the time, how long the tap is opened (shutter speed in photography)

It is optimal, when the vessel is completely filled and nothing overflows! The completely filled vessel is our correctly exposed photo, which our image sensor records.

To fill the vessel, we can also open up the tap to the maximum and close it after a short time periode when it is full.

We could also only open the tap a little to fill the vessel. That way we would have to wait a longer time period before the vessel is filled.

In the figure below we can see the water jet. Pictured below is the aperture of a photo camera. Through the shutter a lot of light "flows" into the camera, when it is widely opened. When the shutter is closed, or nearly closed, (so, it is a very small hole) much less light "flows" into it. The time (exposure time) must be adjusted accordingly.

Take a look on your digital camera. When your digital camera is set to the mode "P", it means "Program Mode", then the camera measures the light conditions when focussing (pressing the trigger lightly) and automatically adjusts its settings to set an appropriate combination of aperture and time. It interesting to know, that you can have an influence on these recommendations by using the rotary knob. Setting the exposure time longer, makes the camera adjust the size of the aperture opening towards a smaller opening. All this can only happen in a certain framework. But you can have different values here. I described, what these values exactly mean, in the chapter about the aperture and exposure time. For know - just try it out!

The 3 aspects of a correctly exposed photo

In the chapter before we took a look at the 2 aspects aperture and time. Now, we take a look at the third and last element important for the correct exposure of a photo: the sensitivity.

The 3 aspects:

• Aperture
• Time
• Sensitivity(of the film/image sensor)

We can imagine the sensitivity in our analogy with the tap and the vessel with different sized vessels.

So, we can increase the sensitivity (or in terms of our example: we just need to use a smaller vessel for the same result "a filled vessel" in the same time).

Therefore we have these 3 aspects for a correctly exposed photo. Which can vary in a certain framework.

For example, following settings will lead to the same exposure!

Shutter speed (Exposure time)	Aperture value	ISO (Sensitivity)
1/200	f/4	100
1/100	f/5,6	100
1/200	f/5,6	200
1/50	f/5,6	50
1/200	f/11	400

Chart: variations of settings of shutter speed, aperture value and ISO

Henceforth, what are aperture value, ISO and shutter speed in photography? The following chapters will examine the individual aspects and interdependencies case by case.

In photography generally the highest possible picture quality wants to be achieved by photographers: However, every one of these 3 parameters aperture value, shutter speed and sensitivity has its advantages (and disadvantages) and pitfalls. The following chapters will shed a light on them.

After we individually take a look on every three of these aspects (aperture value, shutter speed and ISO, the consecutive chapter will be about correctly exposed photos and how we can control if the exposure of a photo is all-right.