Wednesday, April 25, 2007

How's the OOFA?

Leica Summicron 90/2 wide-open

OOFA, out-of-focus areas, how important is lens' OOFA, or bokeh? Over on RfF we're somewhat fond of "lens tests." Threads go deep and long if the subject line states "lens test" or "lens comparison." Big debates (arguments) spring up over the validity of lens tests, particularly when they seem to challenge common wisdom regarding which lens is "better," or, more to the point, if someone has spent beaucoup dollars on a particular lens, and it fares poorly when compared to less expensive lenses. In this case, something must be wrong; the test must be flawed. As any tester will tell you, "no good deed goes unpunished." If you post a lens test on RFF, you'll get the appreciation of those that know the time and effort involved, but you'll surely get your wet-rags that'll let you know where and how your test has failed. That's OK.

My favorite lens tests are not the clinical MTF curves and chart and graphs—although those are important (I guess). My favorite tests are lens comparison tests that show the two characteristics that I look for most in a lens: an understanding of the lens' contrast, and the OOFA. Poor OOFA can surprise you and make-or-break a photo. Quality OOFA, or bokeh, as it is more often referred to, reveals itself in a creamy subtle softness. Highlights, particularly points of highlights appears as perfectly smooth and round. Poorer OOFA highlights look like rings, and even poorer OOFA highlights look like football shaped rings.

Here are some recent links:

Roland (ferider) posted a 40mm lens test on RFF: HERE. Sure it's a comparison of 40mm lenses, but it is a test that shows the two factors mentioned above. If you don't know OOFA and bokeh, look at Roland's test.

Todd (Todd.Hanz) just started a W/NW thread on RFF asking for wide open shots. Check the thread out for good and bad examples OOFA and Bokeh.