Zoom lens at the Zoo

A review of the Sony FE 100–400mm telephoto lens on an A7Riii at the San Francisco Zoo

(Click here to see all photos in higher res)

TL;DR: A heavyweight lens, by all measures


  • Amazingly sharp details
  • Focus is fast and accurate
  • Bokeh is surprisingly nice
  • Fantastic stabilization


  • Heavy at 3.08 lbs
  • After 30 minutes of walking and shooting, my arms wanted to fall off
  • At full 400mm extension, holding a steady shooting position is exhausting for more than a brief moment
  • Did I mention it’s heavy and unwieldy?
  • Expensive is an understatement

Okay, but why?

For the past year, almost every weekend has involved some sort of photography project. The majority of these have been with my Sony A7Rii, which I picked up last March. It’s a great camera, but slow, and in particular it’s hard to keep focused on fast moving subjects. It’s really ideal for landscapes and tripod work. I recently upgraded to the mark iii version, which is dramatically faster, easier to use, and better for catching moving subjects.

At the same time, I regularly go on excursions to wild areas (either by adventure bike or 4x4), and come across wildlife that I simply have been unable to photograph in such a way that I’m happy with. Over the past years, I’ve encountered: Pronghorns, Lynx, Bobcats, Elk, Golden Eagles, Bald Eagles, Stoats, Coyotes, Orcas, Dolphins, and a bunch of other cuties. It’s time to collect these pokemon.

So, a telephoto lens for the Sony FE system is needed.

Luckily, Sony released a 100–400mm last year. Time to put it to the test. What better place than the SF Zoo?

Photo via Brian Smith — a great site for Sony camera fans

Holy smokes, the detail

Let’s start with the most impressive thing about this setup. The sharpness of the lens, combined with the full-frame 42mp sensor and rapid fire ability of the A7Riii body, and even a first “get to know you” session provides amazing shots.

First up, compare these two below photos. The First is a zoom-in that is close to 1:1 pixel aspect (at least on my desktop). The second is the full andun-cropped version of the shot. (Also, I love the expression on this little dinosaur’s face as he tears apart the hay bale.)

1:1 pixel crop. Such a happy dinosaur!
Uncropped. Shot at 200mm, 1/500s, 1000 ISO

With this much ability to crop, you can either optimize for a zoomed out shot and choose a composition later, or for a more distant target (i.e.: any animal outside of a zoo), the ability to crop past 400mm can mean all the difference in getting the shot you want.

These Roller birds were way in the back of an enclosure. This photo is heavily cropped. They still look adorable and with plenty of detail.
Composition options that retain all the detail you could want.

Capturing action

All of the Sony A7 series cameras have fantastic performance in the higher ISO ranges. As such, for most conditions in my traipsing around the Zoo, I kept my ISO around 1000. This generally gave exposures of 1/500 to 1/2000. Because I can trust the ISO performance, I don’t have to waste precious moments dialing settings to capture intense motion. More time shooting means more chances of capturing the moment.

All of the below birds were in motion, and all photos were taken in hi-burst mode. 10fps for 42 megapixel photos is pretty darn insane.

Out of focus ducks. They were having an intense fight. To the human eye, the action was nothing but a quacking flurry of beaks and water.

User experience

(This is a technical bit for photogs — skip to the next section if you like)

It feels silly to talk about, but any given lens will lend a pretty different user experience. For this 100–400, everything is peaches except for the heft, and boy, will that wear you down over time.

To start with, there’s a pretty big difference between the 100mm and 400mm settings, especially in terms of weight. This is to be expected of a massive telephoto lens, but it still leads to fatigue during a multi-hour engagement such as walking around a Zoo.

The lens fully extends at 400mm, moving the center of gravity a good deal. Photo from imaging-resource.com

Trying to use the manual focus ring at 400mm (which engages the MF zoom assist) is all but impossible. So, in situations where manual focus is required at 400mm (bird cages!), there’s a fair bit of dance between finding focus at 100mm (to make careful manipulations easier), zooming back in to 400mm, and repeating the process whenever you or the subject move a few inches. Exhausting.

Metal cages and thick Plexiglas render auto focus impaired or unusable

Auto focus through Plexiglas is also tough. As best I can tell, in photos like with the wolf below, the focal plane was shifted a bit further out. I don’t fully understand why. The camera had no trouble achieving and reporting focus lock (target: his cute little face), and the Plexiglas itself didn’t distort the image too much, so I can only conclude that there was some sort of interference in achieving true focus.

I really like this photo, but I sure wish it was in focus!

Despite the above complaints, the lens really is quite fantastic to use. It even did a great job with a range of subjects, including this pollen producer. I’m confident it would be a great portrait lens (in wide-open expansive conditions). I also have some High Sierra compositions in mind that would benefit with lots of zoom, and that have so far eluded me. I’ll now be carrying this lens on most major trips going forward.

Okay, even more animals

This was a Zoo trip, after all. Here’s a bunch more feathered and furry friends that don’t quite fit my narrative on the lens, but still deserve your eyeballs.

So shiny. So Blue. So Sharp.
Longnecks represent
Old man Mandril sees into your soul
Spoonbills will eat your soul
This Stork was massive and entrancing

That’s it, thanks for reading!

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