What is.......

[Tony]

On pictures like this they claim Lens compression?

 

 

What does it mean?

[Sagitar]

It refers to the way in which objects in the picture are made to look closer together than they really are. So, in that particular picture, the implication is that the motor cycle is not as close to the edge of the weir as it appears. The picture has presumably been taken from a long distance away, using a long focus lens.

 

The term is actually a misnomer. It has nothing to do with the lens. Perspective is determined by the distance of the viewer from the objects viewed.

 

Imagine that you are on a long straight road that slopes gently upwards to the horizon and that a car is parked on the horizon.

 

100 metres towards you, a second car is parked. i.e. the distance between the cars is 100 metres.

 

Imagine standing 50 metres from the nearer car so the second car is 150 metres away from you.  The first car is 33% of the way to the horizon. The second car is 100% of the way to the horizon. It's obvious that the first car is a long way from the the second car because the space between them is occupying two thirds of the distance to the horizon.

 

Now move away from the cars to a distance of 1000 metres from the horizon. The first car is now 90% of the way to the horizon while the second car is still at 100%. From this distance the cars appear to be much closer together because the distance between them occupies only 10% of the distance to the horizon.

 

Now move to 10,000 metres from the horizon and the percentages become 99% and 100% and the cars appear to be on top of each other because the distance between them is occupying only 1% of the distance to the horizon.

 

Of course, by now the cars are just small dots in the far distance so if we want a photograph we put on a long telephoto lens and in the picture, the cars appear very close together though we know they are 100 metres apart.  People call it lens compression, but it is really distance compression. 

 

I have used long distances to make a point but the effect is easy enough to see when you are walking down the street and can see parked cars in the distance. Look at how close to each other they appear when they are distant and how the gap between them opens up as you get nearer.

 

 

[Tony]

Superb explanation, thanks for that and even i who is far from being any form of photography expert understood you perfectly.