Sigma 50-500mm f/4.5-6.3 APO DG OS HSM: Superzoom Bazooka

Sigma 50-500mm f/4.5-6.3 APO DG OS HSM

Can this ‘do-it-all’ lens really replace other similar zooms by surpassing them in quality and versatility? K Madhavan Pillai finds out.

Personally, I am not a great admirer of superzoom lenses. I do not trust them as much as I would an inexpensive 50mm normal or a high-end zoom with a much smaller range. With this Sigma, I did not expect the worst, but I was skeptical. I came away pleasantly surprised.

Features
With DSLR lenses, any lens capable of 5x or more of zoom would be considered a superzoom. At 10x, the Sigma 50-500mm f/4.5-6.3 APO DG OS HSM not just fits the bill, but it also features the highest focal length of any superzoom at the tele end. It is optimised for a digital full frame sensor (the DG or ‘digital’ notation). With an APS-C sized sensor, this translates to 80-800mm. Add to this the optical image stabilisation (OS, which gives you the benefit of four stops) and the Hyper Sonic Motor (HSM, for silent AF), what you get is a lens that is almost perfect for wildlife or sports or big, fat, Indian weddings. The reason it is ‘almost’ perfect is because of the maximum aperture of f/4.5- 6.3. It is acceptable for a lens of this range, but not ideal for low light situations (unless the OS is as good as Sigma claims it to be, after contending with the compromise of using slower shutterspeeds). The lens made up of 22 lens elements in six groups, including four Special Low Dispersion (SLD) glass elements to correct aberrations and improve sharpness across the zoom range (thus the APO or ‘apochromatic’ designation). This lens comes with a removable tripod mount collar, a petal-type hood and a nice, cushioned carrying case. It has a large filter size of 95mm. It is supplied with a step down ring for 86mm filters, for digital cameras with APS-C sensors.

Handling
Weighing in at just under two kilos, the 50-500mm is larger and heavier than other tele-zooms in its category but a lot lighter than tele primes. I found myself enjoying the lens after an hour using it. To begin with, I found the zoom range quite addictive. The zoom ring needs a little more than half a rotation for it to travel through the range. From the texture of a fallen, fungus ridden tree at 50mm to a 500mm close-up of a devotee praying at a nearby temple in the very next instant, I found myself whizzing across focal lengths. The wide, textured zoom ring is stiff, but smooth. I got used to it quickly. The excellent minimum focussing distances of about 20 inches at 50mm and 71 inches (about 6 feet) at 500mm gives this lens a lot of additional versatility. Easily accessible switches on the side of the lens allows the user to switch between AF and full-time MF during AF. A second switch toggles between two OS modes (mode I gives dual axis stabilisation and mode II provides single axis stabilisation for panning) and OS off. A third switch locks the zoom barrel at 50mm and prevents it from ‘creeping’ out when the camera is slung over the shoulder and the lens points downwards. The lens is solidly built. The only lacuna was a slight, but disconcerting, play between the main lens barrel and the barrel on which the mount is attached.

Performance
I tested out the lens on a Nikon D700. The OS proved to be excellent, delivering a consistent three stops of advantage above 300 mm, and up to four stops below this. At 500mm, I was able to make handheld shots at 1/30 sec without camera shake. For a lens of this nature, this is very good. AF was quick and silent. I had no AF locking issues, even at the tele end with the OS on. Control over flare is excellent. Distortion was visible, but much lower than expected. From 50mm to 250mm, sharpness was top notch, even in comparison to similar high-end zooms by other manufacturers. Sharpness showed a drop after 300mm, performing slightly lower than the others. Yet, for a 10x superzoom, sharpness is relatively high, especially at the center of the image, which is good news for owners of DSLRs with APS-C sensors. On the negative side, the lens showed slight purple fringing at the edges after 300mm, which becomes more pronounced towards 500mm. Some light fall-off was visible at the two ends of the zoom range. Stopping the lens down by about one stop corrected it.

Conclusion
In India, the lens comes at an MRP of Rs. 1,11,000, which is about the same as its pricing abroad. The only comparable lenses are the similarly priced Nikon 80-400mm VR and the Canon 100-400mm IS. Over these, Sigma has the advantage of a larger zoom range. Pentax, Sony and Sigma DSLR owners do not have any other choices in this focal range anyway, so it makes a great buy. For Nikon or Canon users, the overall performance makes it a good option. It must be said that this lens cannot replace the much sharper, bigger aperture primes or high-end smaller zoom range lenses. But the cost and the convenience is a deal clincher.