.: Nikon D700, Sigma 70-200 f/2.8 @ 200mm, 1/800, f/2.8, 200 ISO :.

Last year I decided to switch from Canon to Nikon. Switching and upgrading the level of my cameras and lenses was quite expensive, so I made a few decisions to try and cut costs. One of those decisions was to try and shoot a prime lens instead of a zoom in the telephoto range. So instead of replacing my Canon 70-200 f/2.8 IS with a Nikon 70-200 f/2.8 VR or a Nikon 80-200 f/2.8, I bought a Nikon 135mm f/2.0. I was hoping that I would be happier on a wedding day by having a lighter lens which can also shoot more wide open and achieve a creamy blur at f/2.  That was the intent, but in practice that isn’t quite how things have turned out, so I bought a Sigma 70-200 f/2.8 lens to try out.  I compared this new lens to my Nikon 135, to try and find out if I was really gaining any performance by shooting a prime. Read about it after the page break…

What I’ve been finding out is that during the fast paced action of a wedding day, I was really missing the zoom capability.  I like to switch focal lengths a lot, so I’m always changing lenses on my two D700 bodies on my person.  My last two wedding ceremonies were also in churches with restrictions to where I could stand, so I was missing the extra reach of a 200mm focal length. Additionally, the extra stop of low light performance does not really compare with the performance increase of Vibration Reduction (VR) which is roughly 3 stops improvement.  So it can’t really be argued that the prime has better low light capabilites.

But beyond the lack of a zoom, I’ve found that the Nikon 135 f/2.0 is not terribly sharp wide open at f/2.  The sharpness and local contrast performance of that lens improves significantly by f/2.5 to f/2.8.   I’ve also found that when shooting the 135mm f/2 in bright sun, the lens is subject to significant purple and green fringing known as birefringence or blooming.  These artifacts also clear up around f/2.8.  Well, if the lens doesn’t get good until f/2.8, then why aren’t I just shooting the Nikon 70-200 f/2.8 VR, which is regarded to have excellent performance at f/2.8?  Oh, right, because I don’t have the $1900 to spend on the lens right now.

So I decided to try out the Sigma 70-200 f/2.8 lens.  I did a basic little comparison of some photos.  I mounted the camera on a tripod and tried out the lenses at different apertures to see how they compared.  I tested the Sigma and found that it focused accurately on my Nikon D700, and did not need to be micro-adjusted.

Detail Resolution

First I did a series of tests to see how well the lenses can resolve detail  I took a photo of the oh-so-exciting parking lot out in front of my office.  I focused dead center on the red sign in the middle.

.: Nikon D700, Nikon 135mm f/2.0 @ 1/2000, f/2.8, 200 ISO :.

.: Nikon D700, Sigma 70-200 f/2.8 @ 135mm, 1/2000, f/2.8, 200 ISO :.

As you can see, at web size there isn’t too much difference in the images. The Nikon prime lets in a little bit more light, in general.  There is a bit more detail in the shopping cart in the first (Nikon) image. However, the Sigma offers the undeniable advantage of allowing one to get the following two shots from the same position.

.: Nikon D700, Sigma 70-200 f/2.8 @ 70mm, 1/2000, f/2.8, 200 ISO :.

.: Nikon D700, Sigma 70-200 f/2.8 @ 200mm, 1/2000, f/2.8, 200 ISO :.

The interesting part, is what the sign looks like at 100% magnification in these images. Here are the two lenses at 135mm.

.: Nikon D700, Nikon 135mm f/2.0 @ 1/2000, f/2.8, 200 ISO :.

.: Nikon D700, Sigma 70-200 f/2.8 @ 135mm, 1/2000, f/2.8, 200 ISO :.

The Nikon prime lens does a superior job with the detail between the letters of the sign, as it should. The Sigma zoom lens loses a little bit of contrast in the red areas, as well as displays a slight amount of purple hue (birefringence). But overall, I think the Sigma does quite well, considering that it is cheaper then the Nikon and offers the zoom range.

Here are some shots comparing the performance of each lens at various f stops. First,the Nikon 135 at f/2, f2.8, and f/4.

.: Nikon D700, Nikon 135mm f/2.0 @ 1/4000, f/2, 200 ISO :.

.: Nikon D700, Nikon 135mm f/2.8 @ 1/2000, f/2.8, 200 ISO :.

.: Nikon D700, Nikon 135mm f/4 @ 1/1000, f/2.8, 200 ISO :.

As you can see, there is a significant difference in the stop between f/2 and f/2.8.  I don’t really use this lens any more wide open than f/2.5 unless I know that I will only be using the image for web publication, and that 100% crop details will not matter. These photos were shot in overcast conditions. In bright sun conditions, the negative effects are much worse, particularly if the sign was black with white letters. You would have seen significant lines of purple on the white edges at f/2. There is not too much difference between f/2.8 and f/4 in these photos.

And now the Sigma 70-200 at f/2.8 and f/4.

.: Nikon D700, Sigma 70-200 f/2.8 @ 135mm, 1/2000, f/2.8, 200 ISO :.

.: Nikon D700, Sigma 70-200 f/2.8 @ 135mm, 1/1000, f/4, 200 ISO :.

Wide open at f/2.8, the Sigma displays a similar loss of contrast as the Nikon at f/2, but not nearly as bad.  However, the Sigma is able to add detail and contrast pretty quickly.  I took additional images at the 1/3 stops (not published), and I can tell you that there is quite a bit of improvement from f/2.8 to f/3.2, and at f/3.5 the image looks nearly the same as the f/4 image.  So the Sigma trails the Nikon in this particular test in the neighborhood of 2/3 to 1 stop.  Not too shabby for a third party lens.

Lens blur (bokeh)

So why don’t I just shoot at f/4 all the time, since the performance of the lens is better?  Well, I’m addicted to the creamy blur of wide open apertures.  I really like the look when the subject is in focus and the background is out of focus.  It really makes the subject stand out, and can add a dreamy, surreal quality to the image.  Different lenses have different qualities to them, so I took a some shots showing the increase in blur at different aperture stops to compare.

.: Nikon D700, Nikon 135mm f/2.0 @ 1/1600, f/2, 200 ISO :.

.: Nikon D700, Nikon 135mm f/2.0 @ 1/800, f/2.8, 200 ISO :.

.: Nikon D700, Sigma 70-200 f/2.8 @ 135mm, 1/800, f/2.8, 200 ISO :.

.: Nikon D700, Sigma 70-200 f/2.8 @ 135mm, 1/400, f/4, 200 ISO :.

The differences in the blur between the first two photos (f/2 and f/2.8) are quite subtle. More pronounced is the vignetting at f/2. In my opinion the hard to tell difference in the blur is not really worth the very noticeable degradation of image quality.

The difference in blur between the Nikon and the Sigma at the same aperture is also very close. I might prefer the Nikon a little bit, but the exposure is also slightly brighter in the Nikon which could be swaying my opinion.

The difference in the blur at 135mm between f/2.8 and f/4 is clearly quite noticeable.

There is one more thing that the Sigma has in the bokeh department that the Nikon prime does not. The significantly smoother blur at 200mm f/2.8.   This image is the one at the very top of this article.  As you can see, one can achieve a much smoother blur at 200mm f/2.8 than at 135 f/2.

Conclusions

Overall, I’m pretty impressed with the Sigma 70-200 f/2.8. I think it is an excellent value for the money. Wide open at f/2.8, it’s performance falls slightly behind the Nikon 135 f/2 prime, but less than I would expect considering that that the 135 is already stopped down  at that point. I’m less than impressed with the performance of the Nikon wide open.  Not performing well below f/2.8 doesn’t make the lens terribly useful.  (A side note, I have tested the Defocus Control (DC) on this lens in a similar manner, and have found it to be pretty much useless.)   I would be very interested in comparing the 135 f/2 to the 70-200 VR at f/2.8, to see if there is any benefit of the prime at 135mm and f/2.8 at all.  The Nikon zoom also offers the advantages of  AF-S silent auto focus motor, plus modern lens coatings which combat birefringence.  Clearly, this D series lens is due for an update.

Eventually I would like to add the Nikon VR to my collection, as the image stabilization technology would be very useful for dim indoor conditions. But in the meantime, I will gladly use the Sigma for my wedding photojournalism duties, and take advantage of the flexibility of the wide focal range.  I will report back in the comments if any of my opinions change after I shoot the Sigma in real world wedding conditions next weekend.