I own several Sigma lenses and the company has grown recently by introducing their new concept of Contemporary, Art and Sport lens classification. While Contemporary is their consumer (budget) area, the Art and Sport series represent high class lens builds having Art labeled lenses in the lower focal length area and Sport classifying the tele range. High class does not only refer to optical but also mechanical build quality which is both at high standard.
When the Sigma 150-600 came out I was pressing for getting one as it was outstanding at that time related to the focal length range, price and picture quality. This is still true for me although one can see the quality decrease when comparing to a Nikkor 200-400 or 500f4 prime lens. Anyways, still a great choice for low money.
I did a lot of pictures using the 150-600 on several cameras with an emphasis on the D4and was never concerned using other focus points than the middle one as it showed overall good quality.
I also own the Sigma 24-105f4 Art as my standard zoom lens for traveling and short trips. Also here, the quality is very good using my D800 while not as good when I use the D4 which never really made me think.
After a lot of hype in the discussion boards around the Sigma 35f1.4 Art and the Sigma 50f1.4 Art I bought both in the used market. These 2 lenses represent top-level class in regards of build quality, sharpness but also bokeh and micro contrast – a must have! I bought both in the used market and the disillusion came when I tried them out at my D800. Blurry pictures using phase detect AF but very qood quality using Liveview. No proble, using the Sigma dock and Reikan Focal I tried several times to adjust the focus. While at first all seemed to be good, several shots using the lenses were getting out of focus. Finally I sent the 50mm to Sigma asking for adjusting it. Although Sigma claimed that adjusting without camera wouldn’t be sufficient, I did not send my D800 with it. Sigma adjusted the lens then on a reference D800 camera and when it got back, it was slightly better but still lots of pictures out of focus. For some time they stuck in my photo closet.
I recently grabbed the 50mm for some shots of the bypassing Ovation of the Seas and was – again – pleased about the quality if the focus hit the target.
Sigma 50mm Art
Early this year I got attention to the Sigma 18-35f1.8 for DX. As I wanted to restart using the D7200 for landscape and travel photography after I bought the D500, I decided to invest some budget into the DX range. Had the Sigma 30 Art prime since some time with good results in my area of use, I also bought a Sigma 10-20f3.5 to cover the full range for traveling and now the 18-35 which was highly praised everywhere for it’s outstanding sharpness and picture quality.
The first use of the 18-35 was quite surprising. Not a single picture was sharp, the picture quality was not only poor, it was even less than that. I contacted Sigma to get the lens aligned and sent the D7200 together with the lens to them. After it came back (however, not a very good service as it took 3 weeks for this), everything worked fine and during a first test I saw what other users meant when praising the lens.
Sigma 18-35 Art
Shortly after the shots were made a discussion board user asked me whether I could do some tests because of a discussion going on regarding focus points used which are not in the center of the camera with that lens. Although it was related to the D500 with the Sigma 18-35 he asked me because he knew that my combination was freshly back from adjustment exercise.
So, I did the tests and was surprised that nearly none of the focus points outside center ever hit the target and quality of the images decreased the more outer points were used.
As can be seen from above sequence using C1, C3, C6, C9 and C11 focus points from the D7200, the more outside the sensor, the worse the quality gets. The not adjusted D500 did behave even worse.
I sent a mail to Sigma asking for clarification what they did and whether they are able to correct this. After a chat with the engineer it became clear that
- Sigma does only adjust the Center sensor if nothing is stated otherwise in the request
- Sigma can adjust certain focus points depending on the lens. A 50mm Art can only be adjusted to the enter while the 18-35 can also be adjusted outside. What can be done is related to the software related to the diverse lenses.
- Once the lens is adjusted to a camera, other cameras are unlikely to focus correctly using phase detect AF.
Ok, still not a problem for me as I wanted to use the lens just with the D7200 and agreed to resend the camera and lens for a second adjustment.
After Sigma received my stuff I called the engineer and asked him again to make sure that I was looking for all focus points to be adjusted although I mainly would use the center section. He explained possibilities and was confident to get the 18-35 in proper shape. After he had done his work he called me and said that he has now optimized the lens to cover outer sensors as well as the center. The package was sent the same day and arrived one day later (which showed the opposite now, turnaround time for all this was 4 days – very impressive). While the service itself was impressive, the results were not.
Above shows the earlier results on the left and the results after second adjustment on the right.
Now I wanted to see how this behaves in the field; no test charts, real pictures. I setup my tripod and hooked the camera with the 18-35 onto it using mirror-up in the camera to restrict any other influence.
First round was with 18mm focal length shooting an object in around 200m distance. The focus was set to the letter “B” in the “ELBE-1” lettering.
Same focal length but the object in around 60m distance. Focus was set to the orange life-buoy.
Next round was using the 35mm focal length with the same targets as above.
I had another call with the engineer and he told me that the lens is adjusted to the optimum Sigma can do but he also forwarded me to his super visor. The super visor later told me that there is nothing they can do about this. They have done all they can for the phase detect AF and he recommended that I should use Liveview or manual focus in such cases. Well, this is not what I want to do. I was thinking about it whether I can live with this behavior (as I mainly use the center section for my photography style) and finally decided to sell all three lenses.
The 18-35 was not only overlapping focal range but also the one I was considering to be used as a standard lens on DX and therefore should last for more than only one camera without further adjustment. The 35mm and 50mm on FX are also in a range where I do have alternatives but also because I like to use manual lenses more in that focal range while still keeping the 24-105 zoom when I need to have AF.
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