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Does image circle get bigger the closer you focus

Posted: Mon Apr 26, 2010 5:19 pm Etc/GMT-1+01:00
by robinb
HI

Does image circle get bigger the closer you focus

i.e. if you have 250mm when stopped down at f16 at infinity will you get a bigger image circle if filling the frame with a head shot
If so how would I work this out ?

thanks

Robin

Re: Does image circle get bigger the closer you focus

Posted: Mon Apr 26, 2010 5:48 pm Etc/GMT-1+01:00
by dave_whatever
It does absolutely get bigger. If you know what an image circle is at infinity at a particular aperture, you can work out the image circle at any extension with simple trigonometry.

Re: Does image circle get bigger the closer you focus

Posted: Tue Apr 27, 2010 8:33 am Etc/GMT-1+01:00
by timparkin
twice as big when you've got something life size on your screen!