I photograph bands, among other things, in often dark and badly lit pubs and where the difference between focussing on the microphone, guitar strings but not the face can make/break a picture. I need a lens to look serious, but not flashy, to compete with the press boys (& girls). Without wanting to sound self important, people do realise you've got a job to do and give you the space if you look the part and have the kit. It's like a taxi - you expect and are reassured if a decent and safe vehicle turns up.
I've removed the tripod collar and though it's not the shake reduction model, I can handhold at 200mm at 1/50 sec, slow enough to get a drummer's sticks blurred. It handles a dream on my D700; images are bitingly sharp and can withstand cropping. That bright viewfinder really penetrates dark corners of venues and in such confines the 3x zoom range really pulls you into expressions on faces. Shallow depth of field at f2.8, 3.2 or f4 can really isolate your subject, making them more 3D and the lighting can look really effective as it gets defocussed quickly behind them. Zoom back out to include the musicians.
In pattern and nature shots the versatility of a shallow depth of field is a big creative bonus. It focusses quite close - down to 1metre. It's also a superb portrait lens as you can keep a variable but comfortable distance from your subject.
The layout of the focal lengths is in small, simple white numbers on the matt black of the barrel and embellished in gold is "EX Sigma", their top range, as is "Apo" (for apochromatic) which is Sigma's tried and trusted use of special glasses that help focus all three colours of the light spectrum at the same point. You may not know this, but they don't normally and this anomaly gets worse as the focal length increases.
The lovely, ribbed rubber (& chunky) zoom and focus rings are reassuring and to me, in the right place - focus at the front and the narrower zoom nearer the camera. I've now developed a way that I can keep my right index finger on the shutter, my left hand fingers on the focus and fine zooming, for composition, with the top edge of the left thumb, all at the same time. It does sound 'all fingers and thumbs' and only works in practice but the balance with the D700 makes it all fluid and practical. The actions are nicely weighted and smooth - certainly less stiff than my Sigma 24-70 f2.8 EX HSM, whilst IF (internal focus) means that the lens doesn't change in physical length whilst zooming, so zoom creep (either shooting up into the sky, or downward when carrying) cannot be a problem.
A/F is immediate, silent and largely very effective. It can be fooled (or the camera can) by high contrast objects (such as those microphones and guitar strings) and so I prefer to follow the action, ready and wait for my shot and fine tune the focus myself. Most pro's do the same. It's about feeling and being in, control.
The Nikon equivalent might well be one of the best made but the cost, now is round about three times what I paid for this Sigma. Admittedly, that is with their VR (vibration reduction) model, the Sigma equivalent OS (Optical Stabilisation) is around double. That is serious money indeed and well out of reach for all but the well-heeled or successful professionals. But this Sigma is still such a good all-round performer and (comparatively) good value - you get a lot of good glass for the cash - that people will still want it if one needs to sell.
The deep, well made, petal-shaped hood is effective, except if a low sun shines right down the barrel - causing a lot of ghosting, but any long lens will suffer that. A decent, well padded lens pouch with shoulder strap supplied as standard means good portability. The 77mm filter size might seem big but many lenses use this, especially modern, high spec zooms. I use a simple Tiffen 'protector' filter, which is plain glass and currently only £14 on Amazon.
As more pics made with this lens get into my local paper than any other lens I've used makes me wonder how I coped (or not!) before getting this beauty. It instantly became essential kit.