Does image circle get bigger the closer you focus

[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

[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.

[timparkin]

twice as big when you've got something life size on your screen!