The 135 is a beautiful lens and makes amazing portraits. But it’s certainly not the sharpest lens in your bag – it’s just not designed for absolute sharpness. I would say if it’s as sharp at f/4 as your two excellent zooms are at f/2.8 it’s probably about normal.

Roger

Great article, I understand the stopping down a little principle on most lenses but would like your opinion on lenses like the Nikon 200 f2 which is reputed to be at its best wide open or 2.8.

Thanks
Michael

I notice my Voigtlander 58mm has noticeable “bokeh fringing” along high contrast elements in images at f/1.4, but other than that, the combination of sharpness, color, and contrast is very satisfactory, even to the corners on my 1.6x crop camera (on a full frame I’m sure there’s noticable softness and vignetting towards the corners). I have rented the Canon 24mm f/1.4, the Zeiss 35mm f/2, and the Canon 85mm f/1.2 ii, amongst others…and the Zeiss 35 f/2 was the only one that didn’t have noticable bokeh fringing, wide open at f/2. Both it, and this Voigtlander, seem to let so much contrast in (when wide open), that I wind up needing to under-expose by 2/3, to keep the highlights from blowing out so much (or else use highlight tone priority, or similar). Stopped down, the contrast is less of a problem, obviously.

When photographing stars or other pinpoints of light, it’s hard to tell what types of aberration there is, wide open, because the bokeh fringing gives them a soft pink or purple glow.

You can try my (free as in beer) software yourself:
http://sourceforge.net/projects/mtfmapper/

My copy of this lens sharpens very well on stopping down, going from very good at f/2.8 to phenomenal at f/5.6. It is hard to describe this in words — images (produced by MTF Mapper) show that Sagittal MTF50 figures are better than 45 lp/mm in the centre at f/2.8, but somewhat softer on the edges and corners (around 35 lp/mm). Stopping down to f/5.6, however, flattens out the Sagittal MTF50 image tremendously, with extreme corners showing values of 50 lp/mm. (All MTF50 values measured on a D7000, using unsharpened raw images processed with dcraw). At f/1.8, the corners are decidedly soft, dropping to 25 lp/mm in places, and the centre only reaches about 40 lp/mm.

The Meridional MTF50 images were equally interesting: they all had a typical radially decreasing pattern, i.e., high in the centre, dropping off rapidly towards the corners, regardless of how much I stopped down this lens.

So what I found fascinating was that Sagittal resolution appeared to change shape by flattening out on stopping down, while Meridional resolution retained the same “centre hotspot” shape throughout the aperture range.

I have yet to test all my other lenses to see if they behave similarly.

I think it comes down to priorities. I am a sharpness freak, but I rather sacrifice some sharpness for a “WOW” shot. A “WOW” shot to me is a greatly diffused background as a result of using a lens like the 85L or 200L wide open. Yes I sacrifice some sharpness from using f/1.2 instead of f/2 (such as in the case of the 85L) but that to me is worth the extra blur in the background.

Heck, I even photograph group photos wide open at f/1.2 for that background blur. For me, even someone slightly OOF is worth the blurrier background (I make sure nobody is grossly OOF by using focus stacking)

So definitely different priorities for different photographers