This was made for Krzysztof Czub.

It was first of all made to display how different lenses look - field of view and DoF.

People who are getting into the adapter market and haven't worked with still photography ealier might not have a knowledge of the differences between a 24mm and a 50mm lens and different f-numbers (aperture).

This is in no way a very scientific test but I hope it helps somebody better understand lenses and how DoF works.

Things like:
The closer your subject is, the more out of focus the background is.

f/1.8 creates a smaller area that is in focus than an f/2.8

I don't own an f/1.4 or f/1.2 but those lenses would create an ever smaller area that is in focus.

The lower the f-stop number is, the more expensive the lens normally is.

Zooming with a zoom lens will force you to re-focus in order to keep focus on the same subject.

A zoom lens like my 17-85mm f/4-5.6 also changes aperture while zooming - 17mm = f/4 and 85mm = f/5.6

Question / tips welcome.