More on infrared hot spots

Yesterday’s discussion of infrared hot spots did not demonstrate the unpredictible nature of infrared flare, which has little regard for the prime versus zoom debate. Consider the two examples below. Contrast is better with a prime lens, right?

Wrong! Both examples were taken at f11. The top one was taken with the Canon EF 100-400/f4.5-5.6L IS USM and the bottom one with the Canon EF 300/f4L IS USM. The MTF charts suggest that the prime lens should offer notably better contrast than the zoom overall. However, MTF at the center of the image is better with the zoom (at least at 400mm), and in infrared the prime clearly shows the infrared flare problem seen above. It’s no “small” problem—the letter “A” above is about 1300 pixels wide in the original frame! [Thanks to Keeble & Shucat of Palo Alto, CA for loaning me the lenses for this test—a terrific store if you live in the area].