whats up with my FZ200 images

Started 6 months ago | Discussions thread
sherman_levine
Veteran MemberPosts: 6,976
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Re: f/8 (like f/22) isn't always a no-no
In reply to gardenersassistant, 6 months ago

gardenersassistant wrote:

Steen Bay wrote:

gardenersassistant wrote:

It seemed to me that for the centre crops, the f/5.6 crops were sharper than the f/8 crops, and the f/4 crops were sharper than the f/5.6 crops. However, in both the centre and corner crops, f/2.8 seemed less sharp than f/4. I suspect this may have to do with dof. The test chart was the midde two sections of a four section fold-out , so there was a crease down the middle, meaning that it was not absolutely flat. Also, the camera surely cannot have been absolutely straight on to the test chart; the extent of this would have varied with the amount of zoom, as moving between zoom factors meant physically moving the camera and tripod. The f/4 crops might be sharper because the slightly larger dof compensated for irregularities in positioning the camera in relation to (that part of) the target. That said, the area of the centre crop was where I was focusing, so I'm a little sceptical of the dof explanation. Is it possible that f/4 is in fact a bit sharper than f/2.8?

Quite likely. Fast lenses are rarely sharpest wide open.

Ah ha. Thanks for that.

but the falloff in sharpness at full aperture isn't intrinsic to lenses - just that manufacturers tend to push the envelope a bit.

Sherm

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