To be useful to me I had to be sure the lens:
Was perfectly usable wide open at f1.4
Did not suffer from problematic focus shift
Had excellent overall image quality including resolution, colour rendition, bokeh and resistance to problematic chromatic abberations.
Had good performance at minimum focus distance for closer portrait work
Had reliable and accurate autofocus for fast-moving wedding work
Had excellent build quality
The general opinion from my trusted sources seemed to satisfy all these parameters but I was ready to try out and return the lens if it didn't do what I needed it to do, as I already have the Carl Zeiss 85mm f1.4. The Sigma would have to offer something different in terms of its usability envelope to be truly useful to me in addition to the Zeiss lens.
Owing to being busy and the appalling weather I haven't had much chance to do what I'd call real photography but I have taken a few baby snaps and wandered out into the garden to take a few test shots. The first proper outing was a brief trip to Breamore where I took a few shots at varying apertures.
Initial observations are:
Build quality; a cut above most other Sigma's I have seen and very close to the better Nikon lenses. Sigma have really moved their build quality forward and are clearly trying to produce some truly premium lenses now. The new lens barrel coating is a slightly soft, satin, rubberized material, which seems like it should last much better than the previous matte finish that was quite prone to wear and scratches. There is no play at all in any components and even the focus ring seems much better than many lenses, although some way off the wonderful Zeiss ones of course. The lens has a satisfying heft and solidity. It isn't fully weather sealed, but that shouldn't be too much of an issue for what I need.
Autofocus; Really accurate and fast focus from the HSM motor. It is fast enough to allow a degree of action photography, such as tracking moving people which is extremely useful for shooting kids for example. When doing some indoor testing I did find that it was tending to back focus very slightly so I added a setting of -2 on autofocus fine tune on the D700 and that seems to have sorted it. Obviously at f1.4 the depth of field is so small that you can have an eye in focus and the eyelashes out of focus, so one is never going to get a 100% hit rate. Tests seems to indicate that the AF is much faster than Canon's f1.2 lens and at least as good or faster than Nikon's new G series f1.4 lens. Its certainly plenty good enough.
Image quality; The lens is very usable in the central area at f1.4 (obviously as long as focus is nailed correctly). There are some longitudinal chromatic abberations wide open, but they are nothing serious and well below what I have seen on website tests of other 85mm lenses, especially the Nikon. At f1.4 images are very decently sharp, certainly in the center and even can be surprisingly good toward the borders (see first image below). The look is very different to that of the Zeiss 85, which has considerable halation and residual spherical abberations at f1.4, that give a dreamy and surreal look, if you can nail focus. Wide-open use is essential to me for portrait work and its nice to have a choice of a different look to the Zeiss...I'm not too concerned about borders at those settings. On stopping down there is an increase in contrast, which is nothing like as dramatic as the Zeiss 85, when changing from f1.4 to f2. The Sigma has a steady but small increase to perhaps f2.8, where after that there is little if any visible difference. At f2 the lens is very sharp indeed and stopping down any further allows the borders to catch up. There don't seem to be any nasty colour casts. Bokeh can be more buttery than the Zeiss in some instances (especially with a close subject) but at other distances and apertures the lenses' bokeh can be quite similar. The Zeiss has a bokeh character that has somewhat round out of focus elements that are very soft and appealing in their own way and the Sigma generates similar (but not identical) circular effects especially in the highlights. The Sigma's image quality is super and different to the Zeiss, which has that slightly dark and edgy contrast about it familiar to Zeiss users. Overall I'm pleased here as the Sigma does excellently but offers a different rendition to the Zeiss.
Some examples
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| Wide open @f1.4. Slice of sharpness over the scar. Vey surprised how sharp the right border is which by coincidence appears to also be in the focal plane |
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| Quick snap portrait @f1.4. I took 3 shots here, all of which were in focus. Very decent sharpness on the right eye, which was the focal point |
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| At f2 the bite in contrast is greater and the lens seems have dealt beautifully with the subtle light and delivers nice out of focus elements. The rounded highlights at the back are similar to the Zeiss |
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| Stopped down to f5.6. Lovely colour, contrast and biting sharpness |
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| The lens dealt with the harsh highlights well and the textures and separation of the trunk form the background seem very good indeed. f5.6 |
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| Indoor simple snap test portrait @ f1.4. Focus nailed spot on and very sharp at right eye |
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| Close-up shot @ min focus distance and f1.4. Very sharp where focus was aimed at the nodal point of the leaf ribs. Nice contrast and colour |
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| Seems great close up at f1.8. Sharp where it matters and dreamy elsewhere |
