Quote Originally Posted by HDNitehawk


Now I have to ask this, and this questions is for the OP as well: Why? What would a scenario be that aperson would need to know the blur circle of two diffrent lens and try and match them to the same size?
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To be clear, I did not create this tool in specific response to the OP's question. It has existed for some time now, because I was initially interested in exploring the question of which lenses will give me the greatest amount of background blur for a given set of conditions; and as you can see, the answer is not as straightforward as you may be initially led to believe. In fact, there are certain cases where, say, a 50/1.2 will give more background blur than an 85/1.8 but only up to a certain subject-background separation. I was not specifically interested in the point at which two lenses will yield the same blur circle diameter--but this tool happens to be easily adapted to show this.


Developing this tool has helped me to weigh my future lens purchases. It took about an hour of programming and debugging in Mathematica 7, then a few more hours of tweaking to make it look pretty. I plan to put it in a standardized notebook format with appropriate annotations, to prepare it for publication via the Wolfram Demonstrations Project.