# Thread: why are my images blurry on the sides... some one explain this flat field thing

1. ## Re: why are my images blurry on the sides... some one explain this flat field thing

Thinking of reading comprehension, I missed the import of something the OP posted. He seems to be using the long Nikkor teles (600/9, 800/12, and 1200/18) at f/22. Stopping the 1200 down two stops wants f/36, not f/22.

2. ## Re: why are my images blurry on the sides... some one explain this flat field thing

Originally Posted by Dan Fromm
Thinking of reading comprehension, I missed the import of something the OP posted. He seems to be using the long Nikkor teles (600/9, 800/12, and 1200/18) at f/22. Stopping the 1200 down two stops wants f/36, not f/22.
36, not 32?

3. ## Re: why are my images blurry on the sides... some one explain this flat field thing

Originally Posted by Bob Salomon
36, not 32?
18*2 = 36. The 1200/18 Nikkor tele's maximum aperture is f/18, not f/16.

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