I recently purchased the new Sigma 50mm 1.4 DG Art lens intended to replace my Nikon 50mm 1.4G. Whilst the Nikon is a perfectly good lens it tends to be a bit slow focussing and it was always a bit soft towards the edges of the frame (not ideal for portraits as eyes end up out of focus if you are shooting quite open). I wanted a lens that could support the kind of work I do which tends to be either very tight depth of field or lots of depth of field. It needed to be sharp from edge to edge at all apertures ideally - a difficult remit for any lens.
After initially putting the lens on the camera I couldn’t get focus on anything I pointed it at. I then decided to calibrate both lenses in preparation for testing and did some rough and ready tests by locking off the camera and shooting my very exciting bookcase. Note: I had to make much bigger adjustments on the Sigma which was effectively unusable straight out of the box. Sigma – if you are listening then please make sure you calibrate your lenses properly before selling them…(not everyone has calibration equipment).
Here are a few comments on the aesthetics and functionality of the Sigma. The lens is a big hunk of glass. It is a heavy and large lens but it feels well balanced on the D800 and is pleasing to look at with a modernistic and minimalist look. It feels like quality and is beautifully made. The plastic casing has a pleasingly matt and smooth feel to it. The AF/MF switch is solid and the hood fits solidly – in all it feels like a pro lens although it is not weather resistant. This lens focusses a lot faster than the Nikon. It locks on quickly and seems to be as good in terms of accuracy as the Nikon. Manual focussing is smooth and the focus ring has a good tactile ribbed rubber surface.
As far as the differences that I was able to observe in sharpness and quality….the Sigma is not quite as sharp as the Nikon in the centre at 1.4 and the Nikon displays more chromatic aberration. As soon as you go to F2 everything changes right across the frame and its the same story as you move down the apertures. The Sigma outperforms in every department. The bokeh on the Sigma is buttery smooth and although the Nikon is no slouch its highlights are a bit crunchy by comparison.
As far as the cost/benefit is concerned…if you shoot professionally and you need critical sharpness then there is no comparison – Sigma have really created a beautiful lens. If you are on a budget then the Nikon is perfectly good for everyday work and in most cases you probably won’t be wanting. Shooting Fashion means that I am often shooting in portrait mode and I am a bit anal about sharpness throughout the frame.
I am not posting the full size files here but these are screenshots at 100% of various apertures to give you an idea of the quality and a few random shots I took to give an idea of the look out of camera – without adjustments. Sadly I didn’t have a real model to shoot when I wrote this so the Playboy Doll had to do….(dont ask how it came to be in my possession).