The prayer these days is for a sudden favourable shift in the exchange rate, with lenses from Canon, Nikon or Sony in this category now costing as much again as a full-frame DSLR body. Sigma has the answer to that prayer at half the marque price, while now adding the one feature everyone wants, in-lens HyperSonic Motor focusing. Found in all the makers' own 70-200mms, it can now also be found in the Sigma design for all mounts.
 But there are other prayers. The Nikon 70-200mm f/2.8 was apparently designed when DX format sensors were the only forseen future, and has a much sharper central zone than outer field. The Sony 70-200mm, a former Minolta design, is similar and loses sharpness towards the edges in a very dramatic way when focused at its closest distance and set to 200mm. This is a result of a shift to a curved focus field.
We have tested (and indeed own) the new Sigma 70-200mm HSM Macro II in both Nikon and Sony mounts. One of the first things we checked was the coverage on full frame – whether it was fairly even, or had the same tendency to be very sharp centrally at the expensive of the edges. There's certainly some loss as you move towards the corners of the frame wide-open, and it is more noticeable when focusing closer than 3m. But it's nothing like as visible as the centre-edge difference seen in the Nikon, and there is no close-up field curvature issue as with the Sony.
This was encouraging from the start, as the cameras these lenses were destined to be used with are the Nikon D3 and Sony A900. The excellent even coverage of the Sigma produces an image which looks good. No doubt the Nikon and Sony are a bit sharper centrally and have other merits, but neither will focus as close as the Sigma (down to 1m, and 0.38X life-size compared to 0.25X) and pictures taken in the important f/2.8 to f/5.6 aperture range on the Sigma simply look better.
The HSM focus drive appears to be a little slower than the Nikon, but considerably faster than the Sony SSM. This is not a generalised comment, as each lens type will focus at a different speed with sonic motors. The Nikon and Canon 70-200mms are pretty fast and owners may feel the Sigma is either a match, or comes in just behind. The Sony 70-200mm has a very quiet, accurate but leisurely focus – far slower than its screw-driven Minolta 80-200mm ancestor. Fitting the Sigma instead, it feels as if the focus has doubled in speed. It is not just the overall transit time from close up to infinity, but the speed of fine adjustment response which stands out.
I'll confess that I sold my Minolta 70-200mm SSM and its converter in 2008, within a month of the Alpha 900 full frame arriving. The coverage across the frame had been perfect on the Alpha 700 APS-C sensor, and close-ups were sharp enough. On full frame, the extreme defocusing of the edges at minimum focus was not cured even by stopping down to f/11 – and colour fringes were visible when using the 2X Minolta tele converter on full frame as well. I reckoned the lens was worth good money, I clearly was not going to use it much on full frame, and the results I has seen from the Sigma HSM mark II design on Nikon indicated this lens might be better when it finally arrived.
In May 2009 I finally got one (I missed the first batch, the advance orders for Sony cleared it out before I had a chance). It had to be ordered, no question of risking all the next lot selling out through dealers before even a single advert had appeared mentioning them! First thing, I fitted it to the Alpha 900 and photographed exactly the sort of close-up subject which had failed with the Minolta. Bingo! The Sigma had a flat field. It had a flat field even wide-open, and it was sharp – very sharp.
The Alpha 900 has micro focus adjust (as does the Nikon D3) but a series of tests proved that the Sigma needed no adjustment at all. A couple of weeks later, after plenty of shooting, I felt it might just be backfocusing about 2cm around 2m distance but closer and further distances were perfect. Therefore, leave well alone, no need to enter adjustments into the camera which could affect all distances.
A couple of days after getting the 70-200mm in Sony fit, I bought the HSM compatible new type II 2X tele converter. The central field sharpness of the Sony and Nikon lens designs should benefit their converter+lens performance, the more even field of the Sigma might perhaps show a loss – I thought – at 2X. I made some tests using third party unmatched converters, which did not work with HSM, and discovered that the lens was already outperforming the sensor. A converter was not just going to blow up the same level of detail, it was going to reveal additional detail.
The diagnosis was correct! I can't honestly say that the Sigma Apo HSM converter is really any better matched to the lens than the third-party seven element I had tried; the results look very similar. But it works with the lens, and no other converter will. No other converter will work with Sony's SSM lenses either, existing teleconverters just don't translate the focus protocol correctly. They may appear to allow AF but it's hit or miss whether it functions, jitters wildly around a confirmed lock-on, turns off, or just tracks back and forth never finding a focus point. The Sigma 2X with the 70-200mm is impressive because the focus speed seems even faster when the image is magnified.
In this respect, the combination of Sigma 70-200mm HSM and 2X HSM converter proves much faster than the excellent (and expensive) Sony 70-400mm f/4-5.6 SSM G lens. I think I know why. The camera can find the speed of focus change too great and miss the focus, in the absence of a distance range limiter. The Sony lens has a slower focus and a distance range limiter, the Sigma combination has neither. Once the Sigma combination is locked to focus, it will track movement faster. I tried used the Fast and Slow AF options on the Alpha 900, but these have no effect on in-lens motors, only on the in-body motor.
Overall, I know that OEM equipment does have benefits. Things like colour quality, contrast, and bokeh are quoted. I would challenge anyone to show that a Canon, Nikon, Sony or any other lens betters the Sigma in these respects. I never used my Minolta 70-200mm much, and I can't explain why I have started using the Sigma 70-200mm as my normal tele zoom lens. It's the same size, and my excuse used to be that I did not like big lenses. Maybe I was over-conscious of chucking a £2,000 (original cost) lens around at public events, in the landscape, or out in the street.
 
The black Zen finish of the Sigma is certainly more discreet – like the Nikon, and unlike the white-cream colour of Canon and Sony. This has not stopped the usual flow of 'that must be a powerful lens, mate!' comments, but I feel less conspicuous using it. Although durable, it picks up fingermarks and dust quickly enough, like any black finish with rubber grips. My lens began to look handled after a couple of days, and has remained that way.
If I have any problem, it will be travel. The f/2.8 constant aperture makes a big difference with the large viewfinder of the Alpha 900. I do not want to lose this. The neat 2X converter gives me a workable 400mm f/5.6 on demand. But the lens is three times the weight of the 100-300mm I used to carry when flying anywhere.
That f/2.8 is critical for Sony and Canon users. With both these systems, the semi-pro to professional level bodies have f/2.8 AF sensors which only become active when an f/2.8 lens is fitted. They are twice as accurate and much faster in locking focus than the regular sensor points. Nikon does not use f/2.8 sensors, so it's not so much of an issue. I find that the improvement with our Sony A700 and A900 bodies when an f/2.8 lens is fitted is so great I really don't want to switch to a slow, compact long range zoom for travel.As for the results, I process everything from raw and I examine all images at 100%. Working with the Sigma 70-200mm pix depressed me because I was seeing a level of detail and a dimensional quality to the texture and tone of the image I don't get from the convenient mid-range zoom I normally use. Then again, it elated me because the pictures were just magic. Everyday subjects were popping off the screen with the dust on the hairs on the threads of the fabric showing up.
So, I'm stuck with this big lens. That was not my intention. It was supposed to be, like the Minolta before it, a lens which only came out for specific things like sports events. I love the HSM focusing, I'm sure that when Sigma introduce a 12-24mm with HSM I'll be selling my screw-drive 12-24mm and upgrading. Then there's the new 24-70mm f/2.8 which could replace my screw-focus 28-75mm Konica Minolta. I can't afford the Sony Carl Zeiss 24-70mm.
That could leave me using an all-Sigma three lens basic kit for my Alpha 900. That is a new situation. I have used Minolta, then Sony Alpha, ever since the AF system was launched (and before). I have owned and used Sigma lenses since 1974, for this system and many others. The only other systems where I have used Sigma only have been the Fuji S1 to 5 models and the Kodak DCS 14 and Pro full framers, because both these systems supplied Sigma lenses as their official choice. And of course, I've only ever used Sigma glass with the SD9 to 14 Sigma DSLR series and the film models before!
I have aways worked with the makers' own lenses as first choice, and bought Sigma to fill the gaps which they left – often inexplicably – unfilled. That's why I bought a 12-24mm Sigma within a few days of getting the full frame Alpha 900. It is a unique product to do that job, and maximise the wide-angle potential of the 900. These new designs, updated HSM, and the price hikes of recent months turn Sigma into a first choice even where the orginal maker has an option.
- David Kilpatrick |
