Originally posted by Aristophanes The problem with the equivalence argument is that it is based on setting a standard or "sweet spot" of 135 or FF.
Aristophanes, I keep you in high regard, but why can't you understand such a trivial thing? Again ...
1. Equivalence is no argument. And it is setting no standard. It is nothing but a tool (for the discussion of engineers or photographers) which allows to compare two cameras which do not have the same image circle.
By normalizing optical properties to an arbitry sensor size (could be 1 meter diameter to be more in line with iso norms
), discussions are simplified and can become conclusive.
Equivalence is a tool and no argument. Please refrain from quoting it as such. It is driving me angry if a person as intelligent as you can't get it.
2. Because no one except nerds really cares (or wants to care) about the inner workings of their camera (which includes the size of a particular electronic component called sensor), it has become common habit to express a camera's properties in 35mm-equivalent terms. Such as the focal length of a mobile phone's camera. Equivalence now tells us that if focal length is expressed this way, aperture and ISO must be as well. Again not an argument, just a tool.
You may be sorry that 135mm is used as the arbitrary reference point. I agree, but such is history. The Meter is 1/10000000 of the earth's quarter circumference and just as arbitrary. But so what ...
Thank You for listening,
Falk
P.S.
I do not argue (within this thread) if the market is going full frame or not. That's an entirely separate question. The market may go 1" format and equivalence would remain strong as a tool, if not stronger.
If you read my paper, I actually derive in a rigorous way that each optical quality at each moment in time has its "sweet spot" wrt sensor size. And that will in general not be 135. Only sometimes it will.
Last edited by falconeye; 05-31-2013 at 05:57 AM.