So I went for it. Buying new with a Sigma USB dock and Sigma's TC-1401 teleconverter brings the price close to what a good condition Nikon 300/2.8 VR goes for - with the benefit of the zoom. I spent a day tuning the lens with the dock (note: a focus tool is really necessary, I used the Datacolor SpyderLENSCAL). It was a pain in the neck putting the body on, take it off, hook up the dock, then take it off. In the end I was happy I did it.
The Good:
- f2.8 tele zoom with nice, pleasing bokeh
- can be sharp at most focal lengths
- decent AF speed and accuracy with fast AF (auto focus) bodies
- OS (VR in Nikon speak)
- customizable (with the Sigma USB dock)
The Bad:
- bad balance (makes lens feel heavier and awkward to use)
- CA (purple and green fringe on the wide end)
- lens collar
- reverse zoom rotation (for Nikon users)
- slow AF with certain bodies
- flimsy case
I don't use any OS/VR/IS when shooting sports, but it the optical stabilization was great for shooting stills or wildlife handheld. I loved being able to set the focus limiter for whatever I wanted. I set mine for a custom setting in a range for shooting tennis from courtside. This was an improvement for speeding up the AF.
I read other reviews that talked about the balance issue, but I thought it wasn't a big deal. I was wrong. The lens was awkward to use on a monopod because of the shift in weight when zooming in and out. It doesn't sound like much of a problem, but in real world usage, it was for me. This was exacerbated by the reverse zoom direction. I have to wonder why, if making a Nikon compatible lens, with a different mount and AF system, they didn't go "all the way" and make this a Nikon standard zoom direction.
The purple fringe was removable, but I sold some images "off the card" in jpg to clients and the fringe was unacceptable for that. I also read comments about the lens collar. To rotate between vertical and horizontal, there are no "clicks" or stops that let you know when you're parallel. It also is really unsmooth and the collar feels loose when it's open enough to rotate. It's not a good feeling. Shooting sports, I like to be able to swing the lens around quickly, and to do so, felt like the lens might slip out or I was putting a lot of stress on my camera's lens mount.
The purple fringe was removable, but I sold some images "off the card" in jpg to clients and the fringe was unacceptable for that. I also read comments about the lens collar. To rotate between vertical and horizontal, there are no "clicks" or stops that let you know when you're parallel. It also is really unsmooth and the collar feels loose when it's open enough to rotate. It's not a good feeling. Shooting sports, I like to be able to swing the lens around quickly, and to do so, felt like the lens might slip out or I was putting a lot of stress on my camera's lens mount.
The deal breaker for me, came when I put my D750 on it. The AF was slow, hunting increased and accuracy dropped off. It was so bad, I thought I had done something to the lens. I put the D500 and it was fine again. I tried this several times and in different situations, and it kept repeating. I don't know if this is an testament to the D500's AF, but it just wasn't going to useable for low light sports. One of my intended uses was to have a 400/2.8 prime on my D500 with a monopod, and the Sigma 120-300/2.8 on my D750 slung around my shoulder. This wasn't going to happen. To be fair, I'm trying to come up with a way to turn my D750 into a D5, and I don't think the AF would be an issue then.
My last issue was the case. I expect more from a lens in this range, but the case didn't offer a lot of protection and doesn't stay put when slung over the shoulder. A third party option like the Think Tank Glass Taxi would be a good option.
My conclusion is that this is a good special occasion lens. It's not the magical answer to fill in gaps that I thought it would be. The range on a full frame camera is similar to a 70-200/2.8 on a DX or ASP-C sensor. It definitely has a place, but for me, it's not a primary part of my sports kit at this time. Some people swear by the Sigma 120-300/2.8 Sport, so it's downsides for me, are overcome by others.
Sigma is redefining themselves as is evident with this lens, as well as their Art series of lenses. On the bench and lab, this lens looks great, but in real world sports shooting, it could use a few tweaks. It's an admirable effort on Sigma's part to make such a lens, but it could be so much more with just a few improvements or tweaks. As is, if I find one on the second hand market at a price competitive to Nikon's 70-200/2.8 zoom, I'll be very tempted to buy one again.
I really hope they release another version of this lens as it could be (and currently is for many) a really strong tool in the pro sports shooter's arsenal. Sigma's CEO Kazuto Yamaki has stated that they are committed to developing innovative products (such as their 50-100/f1.8) and this lens, and I think that's going to do great things for them and I'm looking forward to what they create next.
Sigma is redefining themselves as is evident with this lens, as well as their Art series of lenses. On the bench and lab, this lens looks great, but in real world sports shooting, it could use a few tweaks. It's an admirable effort on Sigma's part to make such a lens, but it could be so much more with just a few improvements or tweaks. As is, if I find one on the second hand market at a price competitive to Nikon's 70-200/2.8 zoom, I'll be very tempted to buy one again.
I really hope they release another version of this lens as it could be (and currently is for many) a really strong tool in the pro sports shooter's arsenal. Sigma's CEO Kazuto Yamaki has stated that they are committed to developing innovative products (such as their 50-100/f1.8) and this lens, and I think that's going to do great things for them and I'm looking forward to what they create next.