Sigma 50mm F1.4 EX DG HSM A-mount lens review by Yemble
|Yemble#10487 date: Sep-5-2012|
flare control: 5
|ownership:||I own this lens|
|compared to:||Sony 16-50mm f2.8 SSM|
Minolta 50mm f1.7
Sigma 10-20mm f4-5.6
Tamron 90mm f2.8 Macro
|positive:||Body build (focus ring excepted)|
Sharpness wide open
Superb creamy bokeh
|negative:||Focus ring feel|
HSM AF inconsistant
|comment:||Out of the box|
The Sigma 50mm f1.4 has a similar size and weight to the Sony 16-50mm f2.8, but has the appearance of the Sigma 10-20mm f4-f5.6. My copy was marked SLT-A65/SLT-A77 compatible on the box and has a smooth black finish rather than the rubbery matt finish of 10-20mm. The build is best described as solid with its massive glass elements both front and rear. I don’t really understand why there are complaints about Sigma’s rear caps, as it seems perfectly OK to me, as does the front centre-pinch cap. The hood is a reversible bayonet type, the same 77mm diameter as the hood on the 10-20mm, but NOT the same fitting – for some inexplicable reason, they are not interchangeable. A fairly decent generic case is included with the lens, but it has a square profile which is not a particularly snug fit for the lens. The case has a belt loop, but no Velcro release tab.
There are a couple of areas of concern here. Firstly, the focus ring is quite stiff and more importantly not particularly smooth, especially when compared to the Sony 16-50mm. The movement has a tight gritty feel, which will hopefully slacken a little with extended use. Secondly, the front element moves by about 8mm between the two focusing extremes. However, it does this in a way unlike any other lens I own, on a cylinder within the filter area, rather than behind it like most zooms. This internal cylinder looks to be rather susceptible to picking up dust and dirt, so I would say that using a protector filter is highly advisable with this lens to help prolong its life. This movement of the huge front element cylinder may go some way to explaining the unpleasant feel of the zoom ring.
This is my first lens featuring Sigma’s HSM focussing system and to be honest, I am not exactly blown away by it. AF is both quiet and reasonably fast, however, its accuracy seems a little variable, especially wide open. Unlike the SSM on the Sony 16-50mm, which invariably nails the focus at the first attempt, the HSM seems to miss slightly and then adjust, ie. two movements rather than one. The net effect is that HSM focus takes slightly longer to lock than with SSM. Wide open, the full time DMF helps, as it is easy to tweak the focus manually after it locks. From the Dyxum reviews it seems that front focussing appears to be a recurring feature of this lens (on A-Mount at least) and this is true of my copy which required a +10 micro-AF adjustment on my A77. Without this adjustment, shots at f1.4 were a little soft, a point worth noting for owners of bodies that do not have this feature. Once adjusted, shots are sharp at f1.4, very sharp at f2.0 and exceptionally sharp at f4 through f11. I would say that it rivals (maybe surpasses) my Tamron 90mm macro for sharpness at f2.8. It is easy to forget that this is not a macro lens until you try to get in close... at which point you soon hit the 450mm MFD.
The handling of this lens is great on the A77, focus ring excepted; it balances well and fits nicely in the hand, unlike the Minolta 50mm f1.7 which has horrible handling. There is an AF/MF switch on the lens, but this is somewhat superfluous with the A77. In strong light, this lens encourages you to choose very low ISO settings to avoid straying beyond f11. With a minimum aperture of f16, I can see circumstances where a ND or polarising filter would be necessary to get correct exposure… but you’d probably have reached for a slower lens by then! From f4, this is as good as, but not necessarily better than, any other quality prime lens. However, it is below f4 that this lens really performs. Bokeh is absolutely outstanding, with OOF areas both in front of and behind the subject, merging together in a totally seamless way. Someone wrote that the bokeh is as smooth as the head on a pint of Boddingtons… I could not disagree less! Wide open there is some CA which appears as colour shift in high contrast areas rather than fringing – this disappears as the lens is stopped down slightly and is not really an issue. I have not noticed any flare, but then again I naturally tend to avoid shooting towards the sun. It seems unlikely to me that flare would be a major issue with any 50mm prime.