By BENGT NYMAN
Film resolution and later image sensor resolution used to be the limiting factor driving the design of the equipment used in photographic image capturing. For example, we take the continuously variable zoom lens for granted. It was once necessary to accurately frame just the part that we wanted to become our image. Despite the time and effort required to do this during the photography itself we have become used to doing it to take maximum advantage of the resolution of our camera. Now imagine that you don’t have to do that. Imagine that your camera resolution is so good that you can afford to cover your desired image with a healthy margin, leaving framing and cropping to the post process.
That is actually where we are today.
I predict and suggest that this paradigm shift will drive the design of lenses in a new direction. It’s a well known fact that the optical performance of a zoom lens is a compromise compared to a prime lens. I believe and suggest that at the top end of the quality spectrum new dual focus prime lenses will reappear and replace continuous zooms. Let me give you an example. Take Nikons new and superb 200mm prime lens, the sharpest lens ever tested by DxOMark. Build into this a 2x extender, somewhat like the 1.3x extender built into the new Canon 200-400mm lens, except leave out the zoom.
You now have a lens that is either 200 or 400mm with a flip of the wrist, but it is not a zoom, it’s a 200 or 400mm prime lens.
Post-processing framing and cropping easily covers the 2:1 range between the two focal lengths producing an image superior to that of any continuous zoom.
I shoot this way, using strictly primes. But to make it possible I carry two cameras. Sometimes one with a 35 and one with an 85. Other times with an 85 and a 200 and occasionally with a 200 and a 400.
I am looking forward to the day when dual focus prime lenses let me leave one camera at home.