08-03-2017, 08:36 AM
Quote:Hi Dave,Hi Miro,
You already received many suggestions and possible cause of this issue.
My proposal is to exclude some of them. To do this can you please make test image in more LAB environment?
E.g. shoot flat peace of newspaper with controlled light condition – use different focal length and aperture, For calibration you can use old trusty lens with similar focal length.
Other interesting lab test is AF accuracy at different AF points.
Regards,
Miro
I haven't the appropriate building for shooting such tests.....I live on a 9.3 mts boat.
However, I will post further examples as and when I come across them, on a flat plane this effect does not show up, I think it's to do with the quailty of the Nissan bokeh at the focus transition which causes this strange softness, the outer edges are hard and highlighted and while the center of the stem is somber and transparent.
The Tamron A011 (G1) hasn't the softest OOF rendering with onion ring bokeh as well and I noticed this patchy softness, the G2 has much softer bokeh and I see the issue less often. The Nikor AF-S suffers from Nissan bokeh in front of the plane of focus, but is soft in nature behind.
Another weird bokeh effect is bubble bokeh, again I have the Helios 44-2 which produces the bubble effect, but the distance between the subject and the background has to be just right or the effect doesn't happen. Like moiré conditions have to be just right to see it.......(or wrong depending on your POV)!