Monday, January 15th 2007
In response to this thread over at photo.net I decided to test my copy of the Canon EF 50mm 1:1.4 USM at various apertures.
The question posted in the thread is basically
Can the Ef 50mm be used at f/1.4, or is it only sharp at f/2.8?.
Since it is late at night here, my test subject is rather boring. It’s a Volvo brochure laid out flat on my floor:
However, the tiny text is good for showing lens sharpness.
I shot test pictures at f/1.4, f/2.0, f/2.8, f/4.0, f/5.6 and f/8. Here are the obligatory 100% crops. I should add that the images where shot with sharpness set to 3 (out of 7) and contrast at -4 in my 30D.
As you can see, at f/1.4 the edges are slightly soft. The edges are sharper at f/2.0, and even sharper at f/2.8:
From f/2.8 and up, the results are pretty similar:
So, to answer the question: The Canon EF 50mm 1:1.4 USM is not as sharp at f/1.4 and f/2.0 as it is at f/2.8 and above, but I’d say it is definitely usable.