Sigma 30 1.4 Wierd Bokeh In Extremes

Started Jul 12, 2005 | Discussions thread
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MartinM2
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Sigma 30 1.4 Wierd Bokeh In Extremes
Jul 12, 2005

Just got my new Sigma 30 and thought I'd share a strange thing I noticed on a few shots.

First off, optically this is probably the sharpest lens I've seen in the center wide open, I think it even beats my 85 1.8.

But I have two issues with this lens from the few shots I've taken today.

1) Focus Inconsistency - Maybe I'm just getting used to the extremely narrow DOF or maybe the focus ring just needs to loosen up, but focus consistency seems to be a little hit and miss wide open. I did some testing on a test chart and it was spot on, yet real world subject were not entirely consistent.

2) OOF Highlights in the edges/corners is not your typical roundish (circle, octagon, pentagon etc). Wide open more typically these are just larger creamy bokeh, but if your focus distance is just right and you're slightly stopped down, the OOF highlights in the extremes of the frame take on a cone shape turned on it's side.

Has anyone else noticed this? I noticed a few non circular shaped OOF highlight on some other examples, but nothing quite like this. Again this is not typical, but I don't believe in giving nothing but rave reviews to justify my purchase, if I notice something wierd, I'm going to include that.

Having seen this and my concern about focus consistency is changing my view of this lens. It's sharp and a great lens, but I'll have to give a "Hale to the King"...the 35L will continue to be king..;)

If only I could afford it!

I'll play around with it for a few more days to get a hold on the focusing, but I was curious at least to find out if anyone else noticed this bokeh effect.
Thanks!
Martin

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