Sigma is currently on a roll and putting out some really great lenses; especially for L-mount and m4:3 mount cameras. I recently bought the 85mm f1.4 DG DN Art lens for full frame L mount and found it just as good, optically, as their original 5 pound 85mm 1.4. You remember that big, hulking lens ---- the one that made Zeiss Otus 85mm owners weep openly at the thought that they could have three copies of a better lens for the price they paid for their manual focusing one...
The 85mm I replaced the earlier 85mm with is not an outlier when it comes to lens performance from Sigma's art series. I also own the 20mm f1.4, and the 35mm f1.4 and find both of those lenses to be an unusual combination: high optical performance and yet priced low enough to be accessible to most users.
But this year my experiences with their Contemporary 45mm f2.8 led me to look at more lenses than just the Art lens series lenses for full frame. In the early part of the year I picked up the 16mm f1.4 DG DN Contemporary series lens and was quite impressed with its performance, even wide open, when used on various m4:3 cameras. A month ago I was in my favorite camera store when I spied a lens I'd read about but never used. It's the 56mm f1.4 DG DN which is available in either m4:3 mount or e-mount. I only covers up to an APS-C sensor so it's not for full frame camera owners but I guess you could use one on any of the Sony A7 series cameras in the "crop" mode.
I asked the salesperson if I could see the lens on a camera body and he stuck one on a GH5 and handed it over. After I cleaned the fingerprints off the demo GH5 and set the diopter correctly (for me) I walked around the store focusing on stuff to see how fast the AF is and also shooting frame after frame so I could evaluate the sharpness wide open.
The view through the finder was impressive. Bright and snappy is a good way to describe the performance.
The lens is rather small; about the size of a "nifty-fifty" from the days when both Nikon and Canon made reasonably sized normal lenses. That makes sense since the lens is basically the same focal length. It's faster than the economy normals but it doesn't have to cover the full 35mm frame so it doesn't need to be much bigger.
If you use this lens on an APS-C Sony it will give you a full frame angle of view equal to an 84mm lens. If you use it on a m4:3 camera it will give you a full frame angle of view equal to about 112mm. Unlike the barebones f1.8 normals this lens is an f1.4 and uses both a super low dispersion element and a couple of aspherical elements. The lens design is more complex, with 10 elements in 6 groups. The aperture uses 9 blades for better out of focus rendering and the filter diameter is a nice and calm 55mm.
Sigma has done a wonderful job with this lens. Many times you'll buy a fast, f1.4 lens and not be able to use it (convincingly) until you stop it down a stop or two. Many fast normal lenses are okay in the center of the image area but fall apart on the edges and in the corners when you use them at f1.4. You kinda wonder why you bothered to pay for the two extra stops if you can't get the shots you want without having to stop down to f2.8. The 56mm repudiates that trend. It's very sharp in the center at the widest aperture and more than sharp enough on the peripheries. And the lens has "bite."
To evaluate its resistance to flare be sure to look at fourth and sixth images below. Both have direct, hard lights shining directly into the frame and both images were taken with the lens at or near full aperture. You'll see very little flaring and no weird rays or artifacts. In this regard the 56mm performs better than lenses I've owned which cost three or four times as much.
In terms of size and weight balance (the unit weighs right around one pound) this lens is a perfect match for a camera like the GH5 or G9. It's also a perfect match for those cameras when it comes to focusing. Even in dark areas and weirdly lit scene the S-AF was quick to lock on, didn't hunt and was absolutely accurate.
If you are mostly in love with wider angle lenses we'll understand if the longer focal length on m4:3 isn't your cup of tea but if you really like doing portraits and wish you could have more control over depth of field when shooting in m4:3 then this lens is a worthy contender. It's usually priced at $479 but every one in the camera industry has most of their stuff on sale right now so I'm seeing consistent pricing here in the USA of around $429. I wish it was $100 but then I also wish I had a V-12 engine in my Subaru Forester and I also wish that V-12 would get 40-50 miles per gallon driving around town.
It was refreshing to walk around downtown at dusk and into the "dark blue" hour. I let the camera roam around the ISO settings by putting it in Auto ISO and setting the ceiling at 3200. This was a nice opportunity to use the lens at its widest apertures without having to resort to neutral density filters or super high, electronic shutter speeds.
Why have this lens for the GH5 when I also have the 85mm Art lens and a 90mm Leica lens for the full frame, S1 system? Well, the way I see it, the big stuff is for work and the small stuff is for play and personal work. It's okay to have both. Multiple systems come in handy for lots of stuff. But I have to say that the 110mm focal length is quickly becoming one of my favorites for quick, tight shots and art in available darkness.
Note the lack of flare from the oncoming headlights.
Focuses down to about a foot and a half. Not bad considering the angle of view.
Note the lack of flare from the spotlight over the mannequin's right shoulder.
The Seaholm development, built around the bones of a retired power plant, lights up the evaporator stacks for the holidays. It's a fun look.