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Testing: Sony a7 Full-Frame Mirrorless Camera

By Norman Chan

My experience shooting with this almost-pocket-sized full-frame camera.

For the past three weeks, I've been testing the Sony a7 camera. It's not a camera I bought, nor one provided by Sony--BorrowLenses was kind enough to give me a free rental to test both their service and the camera. And during testing, I've been carrying it around in my camera bag along with the Canon 6D. They're both full-frame cameras, but they couldn't be more different. While the 6D is a traditional DSLR, Sony's a7 is a mirrorless camera. It's more akin to Sony's Alpha NEX lineup of compacts--cameras that are physically the size of a large point-and-shoot (at least one from around 10 years ago), but have the large image sensors of DSLRs. And in using the Sony a7, I've been brought back to the fun of shooting with my old NEX-C3.

We've previously talked at length about the differences between mirrorless cameras and DSLRs, so I won't go into those technical details again. The upshot is that mirrorless cameras have the potential to be much smaller and lighter than traditional DSLRs, but omit a optical viewfinder. (The a7 uses a built-in OLED viewfinder, like the one Sony put in the popular NEX-7 mirrorless camera.) This makes the camera a really interesting comparison with the 6D, which is the smallest full-frame DSLR in Canon's line-up. The 6D weighs 1.7, and when coupled with the awesome 24-70mm f/2.8 zoom lens, weighs almost three and a half pounds. The a7 only weighs 1.3 pounds, and that's with the 35mm f/2.8 Zeiss lens attached.

F 2.8, ISO 1250, 1/60s

The a7 being physically smaller than the 6D also meant I was able to take it many more places than I would the 6D--I didn't have to worry about carrying a backpack or shoulder bag to stow a camera when walking around at night. It didn't quite fit in my jacket pocket, but it was light enough to walk around with a strap wrapped around my wrist. At SXSW, I brought the a7 when going out every night to photograph the night light and conference events. At the Game of Thrones prop and costume exhibition, event staff specifically asked people with DSLRs to not take photos, but didn't take a second look at the a7. It's not small enough that I would feel comfortable taking through the mosh pit of a rowdy concert, but it also doesn't scream "I'm here to take photos" like a DSLR with a big lens does.

We cover a lot of my thoughts about the a7 in the video review (I was really pleased with it), but I wanted to flesh out some of my takeaways from using the camera, and show off some sample and test photos.

The OLED Viewfinder

I never got fully accustomed to using the OLED viewfinder on the a7. It has a very high pixel density, its colors are bright and vibrant, and there wasn't any major lag, but it still can't compare to an optical viewfinder. What I found most lacking was the sense of depth in the viewfinder screen--shallow focus was difficult to pinpoint without the use of peaking assist. I really liked that the viewfinder could be used to review images and also show the same on-screen information as the tilting LCD, but found the proximity sensor that activated the viewfinder too sensitive. When shooting low from the hip (and LCD flipped up), the viewfinder would occasionally flip on, meaning the LCD would also turn off.

Physical Controls

Having clicky dials for aperture, shutter, and exposure compensation was awesome. Really really awesome. The placement of the dials isn't ergonomically optimal, but it didn't bother me since I mostly shot in aperture priority and adjusted the front dial with my index finger. The exposure dial was my favorite to tweak, and has the most satisfying click. As others have complained, the menu dial on the back of the camera was too easy to accidentally rotate. And since it's permanently bound to ISO, I took a few shots at ISO 50 when I really wanted to use auto-ISO. The smaller body of the camera makes the physical dials feel a little bit cramped, and I thought the zoom button was a little out of place.

Peaking Focus

I forgot how much I enjoy shooting in Sony's DMF focusing mode, which combines auto-focus (I used center spot focus) with manual tweaking. Peaking highlights the sharp edges of the scene on the LCD and viewfinder, which helps a lot when shooting at wide apertures. It's something I still wish was an option on Canon DSLRs when shooting in Live View mode (ie. using the LCD instead of the optical viewfinder).

Focusing Speed

Auto-focusing with the a7 was fast in normal lighting, but didn't feel dramatically faster than what I was used to on the 6D. The a7 uses a hybrid focusing system (both phase and contrast-detect), which helps in movies and for shooting moving objects. I'm not great at shooting fast-moving objects so the thing that held my photos back was my skill, not the camera's focusing speed. It's why I still prefer center spot focus and then re-framing compositions. Autofocus in low light was noticeably slower than in well-lit situations, but not substantially, and didn't affect my ability to photography walking subjects.

Reviewing Images

Reviewing images on the fly with the a7 was a bit clunkier than I would have liked, even after getting used to the controls and placement of the playback buttons. Even though I shoot in both RAW and JPEG, the camera reviews JPEGs, which didn't show as much detail as I needed to discern the subtle differences between two sequential shots.

Auto ISO and Shutter Speed

This is the camera that really got me comfortable shooting with auto ISO, set with a floor of ISO 100 and ceiling of ISO 3200. The metering was such that in evening shots, the camera would most often choose ISOs between 2000 and 3200, and the images still looked great. One thing that bugged me was that auto ISO frequently set the shutter to 1/60, even when the ISO was a relatively low 400 or 640. I would have preferred bumping the shutter to 1/120 or even just 1/80, and raising the ISO in those cases. Too bad the camera doesn't let you set a floor for the shutter in auto ISO mode.

Blurry image the a7 took, because auto iso was set to 1/60s shutter.

Wi-Fi and Apps

Remote shooting is still a novelty, but it works well and you have lots of control over camera functions with the smartphone app. Wi-Fi transfer of photos from camera to phone is much more useful, and something I did frequently while waiting in line at SXSW or during any other downtime. It does have a noticeable effect on battery life. And while the menu system of the a7 is much improved from the tile-based menus of the NEX cameras, launching apps still requires loading a new interface that's slow to load. The time-lapse app I tested worked OK, but I don't think it's worth $10. You're better off using a free smartphone app.

Video Shooting

I didn't get to test much video work on the camera, though will note that the a7 has both audio in and out jacks (with on-screen audio levels!), as well as HDMI-out for monitoring or video capture. Video records at up to 1080p 60fps, and at up to 28Mbps bitrate. In my light testing (and the shooting of a premium video on the site, I used the 1080p 24p/17mbps setting. The high-quality videos are saved to AVCHD format, but Quicktime can easily convert them to .MOVs for ingesting into editing software.

Battery Life

On a full battery, I wasn't able to use the a7 for one full day of shooting. Luckily, it takes the same batteries as previous NEX cameras, so I had a few spares as well as a wall charger. If I didn't have those, I'm not sure I would've been comfortable bringing the a7 out by itself for shooting SXSW. The camera is rated for 340 photos on a battery, but I'd put that much closer to 300 if you're reviewing photos or using Wi-Fi as well.

Lens Ecosystem

This is the primary reason I wouldn't buy the Sony a7 today, even if I didn't own the 6D. Sony has only announced five FE (full-frame E-mount) lenses for the a7 and a7r, and I don't think they're enough to fill all the needs of a serious photographer right now. The 35mm f/2.8 I tested was the smallest of the lenses available, and the size of the zooms actually take away from the portability of the a7. It's a great lens, but I definitely felt the need to go wider (both aperture and focal length-wise) at times. The 24-70 f4 is probably the most versatile lens in the lineup, but I know many people will be holding out until Sony can show that it can make a f/2.8 zoom.

Image Quality Tests

As promised in the video, here are some image samples at ISO 100, 800 and 3200. The first photo in each series is resized to 1920, and the second is cropped-in. Click the second image to see it at actual size.

f/2.8, 1/400s, ISO 100
Click for full-size.
F/2.8, 1/60sec, ISO 800
Click for full-size.
F/2.8, 1/50sec, ISO 3200
Click for full-size.

As I mentioned, ISO 3200 photos looked really fantastic on the a7. Noise is noticeable is you scale to 100%, but there's not a lot of detail lost in edges or shadows. And when resized for use on web, it's more than acceptable. At ISO 6400, edges start losing their fidelity, and colors get a little muddled any higher than that.

I also took a series of photos in my garage, at various ISO settings and with both the a7 and 6D. This isn't a perfect setup to emulate a DPReview-style image-quality test, but I did want lots of objects in the background and casting shadows to evaluate detail loss at higher ISOs.

ISO 100, Sony a7 (left), Canon 6D (right)
ISO 800, Sony a7 (left), Canon 6D (right)
ISO 3200, Sony a7 (left), Canon 6D (right)
ISO 12800, Sony a7 (left), Canon 6D (right)

I think that up through ISO 3200, the Sony camera performs slightly better than the 6D, and the extra 4MP of pixels (crammed onto the same sensor size) actually contributes to more image detail. Above ISO 3200, though, the Canon camera retains colors and edges far better than the Sony.

Conclusion

Shooting with the Sony a7 was a ton of fun at SXSW--it really reminded me of the days when I took the NEX-C3 around New York during our 2012 MakerFaire trip. All the techniques and mannerisms of shooting a smaller mirrorless camera (with an articulating LCD and focus peaking assist) came flooding back to me, but without the worry that I was sacrificing image quality for portability. My wrist and arm ached a little when going back to the 6D this past weekend. The one thing I did feel like I was sacrificing with the a7 was focal length and focusing prowess--the 35mm lens was too limiting for some types of shots I wanted to get, and the electronic viewfinder was merely sufficient. As I said in our video, Sony has an exciting camera, but not an exciting camera ecosystem. Even if you're in the mirrorless camp and want to upgrade from an APS-C NEX camera, you should wait a year or two until the lens ecosystem matures.

Find more of my test photos from my time with the Sony a7 camera in this Flickr set.

Thanks again to BorrowLenses for providing the camera and lens rental for my testing.