Sigma 85 f/1.4 Art

[Kayaker72]

Are all those MTF charts at the same f-stop?

Hi Joel,

The blue lines are f/8 and the black lines are wide open. So, of course, wide open will vary between the lenses. The thick lines are 10 line pairs/mm (indicator of contrast) and the thin lines are 30 lp/mm (indicator of resolution). Further up the chart, the better, the closer the solid to dashed line, typically the more uniform the bokeh.

A quick write up on it from Canon and luminous landscape:

http://www.learn.usa.canon.com/resou...F_charts.shtml

https://luminous-landscape.com/mtf/

I would say that the new EF 85 f/1.4 IS is a bit better than the EF 85 f/1.8. So, the IQ you have at f/1.8 with older lens, you'll now have a bit better at f/1.4 with 4 stops IS with the new lens. And the 85 f/1.8 is plenty sharp. So I expect the new lens to be great. But, it is just a little bit behind the EF 35 f/1.4 II:
http://www.the-digital-picture.com/R...mp=0&APIComp=0

the Sigma 85A:
http://www.the-digital-picture.com/R...mp=0&APIComp=0

or the Zeiss Otus:

http://www.the-digital-picture.com/R...mp=0&APIComp=0

At least that is my perception based on the MTFs.

As I thought about this, as a portrait lens, that is likely fine. Good bokeh/contrast is as important if not more so than straight up resolution. And looking at the MTF, 10 lp/mm is almost at 90% on the 85IS, so I expect good contrast. Resolution is down around 60% which is meh. The dashed and solid lines are reasonably close, so I expect fairly uniform bokeh. This should be a good portrait lens, but the MTFs are not indicating that it is a world beater in terms of resolution.