Trading down to upgrade. A tale of 2 Sigma lenses.

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After a positive Sigma 3 lens run, outlined by the 3 previous posts in this blog. I reached high for a 4th lens and then stepped back.

Reaching high.

The much ballyhooed Sigma 18-35mm f/1.8. Definite ‘yay’, followed by an ‘ah’ experience.

The ‘yay’:

  • A world first f/1.8 zoom.
  • Nothing short of remarkable sharpness, even wide open, across the frame.
  • No vignetting that I could find.
  • Colors, colors, the wonderful amazing colors.
  • Built like a tank and finished as good as some of the highest grade lenses made.
  • Focus good news. Up close through viewfinder bang on. Any distance using live view bang on.
  • When focus was on this lens was the equal of my favorite prime lenses. It was like turning your wrist to go from a wide to standard field of view high quality prime without reaching in to your camera bag, possibly missing a shot, or exposing the mirror to the elements.


The ‘ah’:

  • Personal preference, but 35mm did not meet my intended goal of a full frame equivalent 24-70mm field of view to compliment my full frame/70-200mm combo. Knew this going in. Isolated this is not a big deal, but factored in with the next bullet it did not help.
  • Focus bad news. Given the reviews I had braced myself for some inconsistent focusing, but through viewfinder past 3 or 4 feet it missed focus every single time. Every. Single. Time.

Compounding matters was the fact that it focused just close enough so the picture often looked fine on the back screen unzoomed. So you would think you got a good shot only to realize that the focus missed during post processing. I.e. way too late to do anything about it.

The real nail in the coffin came about when trying multiple times to take a sharp picture of my son at a distance greater than 3 or 4 feet in a well lit space.

A lens that cannot focus through the viewfinder on a DSLR? Having to remember, with just one lens, to shoot a DSLR at arms length using the back screen all the time for focusing only? No.

Still clinging to the sharpness in denial I tried every setting one could imagine. No change. No improvement. In camera focus adjustment past 3 or 4 feet would not improve things since that would ruin close viewfinder and live view focusing. Focus distance from object not focal length was the issue so Sigma’s focal length fine tuning puck add on would not have helped.

The Sigma 50mm EX f/1.4 I have also had issues reported, but that seemed to depend on whether you got a good copy or not and I lucked up with a good one. But after more research (Page 11 of Pentax Forums review specifically) it would seem that this was a fairly consistent problem with the Pentax variant.

Even with that information the in focus shots were so good that I literally had to summon a support group to shove me towards what I already knew. It had to go back.


KEH was great about it and set me up with a return right away.

What to do?

Stepping back.

Adorama and Sigma to the rescue. As I have mentioned before I stalk check the used section of my favorite retailers regularly for new arrivals. Right on time a previously designated back up lens came in at a price I could not refuse. Over $300 less than the 18-35mm f/1.8 used and $120 off the new price I jumped on a newly listed Sigma 17-50mm f/2.8. Great reviews and it was an easy choice. Findings so far:

  • Although not as sharp at f/2.8 as the f/1.8 wide open (no other zoom that sharp and none that wide) it is close enough for me, and it focuses swiftly, and more importantly accurately, whether I use live view or the viewfinder. What good is sharpness without focus?
  • HSM that focuses quickly and silently like the 18-35mm. I love my Tamron 28-75mm on full frame, but in quiet, close quarters the old tech screw drive can make quite the racket.
  • Surprisingly competent in low light.
  • Reaching 50mm it meets the full frame field of view I was seeking at an equivalent of 25.5-75mm for the 2 body shooting compliment with the full frame/70-200mm.


I plan on letting it live on my K-70 for a while so I expect this gallery will be growing. Until then here are some sample shots I took over the weekend.


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