left focus syndrome , cured yet?

Started Jun 3, 2013 | Discussions thread
Per Baekgaard Senior Member • Posts: 1,268
Re: left focus syndrome , cured yet?

_sem_ wrote:

See loCA ("bokeh fringing") samples at the bottom of the page:


I thought I was quite familiar with both LoCA and also many of the photozone.de tests in general

When I look at the shot you linked, even the (most) in-focus areas have a slight purple/magenta tint at the widest apertures which is also part of causing the drop in contrast. I would assume it is more visible at larger magnification.

There are probably better examples of the purple fringing that the OP observed here:


Look for the pictures roughly 3/4 down, with a note saying "More chromatic aberration at f/1.4 on both lenses..."

Or were you saying the purple tint the OP observed is not LoCA? If not, when what in your mind would it be?

Notice the focus shift - the point of sharpest focus may move upon stopping down the aperture.

Yep, some lenses have this problem -- some in weirder ways than others (see e.g. my test of the otherwise nice 17-55mm here: http://www.b4net.dk/?page_id=35). As far as I know, some of the focus shift is not a demonstration of LoCA per se, as it typically is a combination of various non-compensated aberarrations.

- Per.

 Per Baekgaard's gear list:Per Baekgaard's gear list
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