Sony A7 II Review
|Full model name:||Sony Alpha ILCE-A7 II|
(35.8mm x 23.9mm)
|Viewfinder:||EVF / LCD|
|Native ISO:||100 - 25,600|
|Extended ISO:||50 - 51,200|
|Shutter:||1/8000 - 30 sec|
|Max Aperture:||3.5 (kit lens)|
5.0 x 3.8 x 2.4 in.
(127 x 96 x 60 mm)
includes batteries, kit lens
|Full specs:||Sony A7 II specifications|
A7 II Summary
Sony has yet another winner on their hands with the A7 II. By addressing some of the design and ergonomic quirks of the original model, as well as providing a notable technological achievement with their 5-axis image stabilization -- and some subtle, yet worthwhile, performance enhancements -- the Sony A7 II is a more matured, more well-rounded camera and therefore an even more enticing option for those wanting full-frame image quality but not a full-frame DSLR-sized camera.Pros
Excellent 5-axis sensor-shift image stabilization; Sensor-shift IS brings stabilization to nearly any lens; Much-improved ergonomics and top-deck control layout; 'Mark II' maintains same impressive image quality, dynamic range and high ISO performance; XAVC S 50Mbps video format; Faster start-up time; Hybrid AF performs well with good continuous AF.Cons
(Similar to A7): Loud shutter (but electronic first-curtain helps); Battery life could be better; Low-light AF still not as good as most DSLRs; High ISO JPEGs look over-processed; Slow buffer clearing; Limited selection of native Sony FE lenses (but it's getting better).Price and availability
The Sony A7 II originally began shipping in December 2014 in two configurations: body-only for about US$1,700, or in a kit bundled with the FE 28-70mm f/3.5-5.6 OSS zoom lens (model SEL2870) for about US$2,000.Imaging Resource rating
5.0 out of 5.0
Sony A7II Review
Overview by William Brawley
Sony unveiled the latest addition to the A7-series of full-frame mirrorless cameras, the new Sony A7II this past November. The "Mark II" model features not only the world's first 5-axis sensor-shift image stabilization system for a full-frame ILC, but also a number of design tweaks and build quality improvements.
Originally seen on the Olympus E-M5, a 5-axis sensor-shift image stabilization system compensates for yaw, pitch, and roll, as well as vertical and horizontal motion. The Sony Japan website indicates that the new 5-axis system on the Sony A7II should provide up to 4.5 stops of stabilization correction. If you recall, Sony made a big investment into Olympus back in 2012, and using their partnership, it could be that Olympus' technology for body-based IS is making its way into Sony Alpha cameras. (Sony of course has also had body-based IS technology in some of their cameras for years, but the 5-axis aspect of this system is an advancement into an area where Olympus already had expertise.)
Interestingly, the A7M2's sensor-shift image stabilization works in concert with the Optical Steady Shot system built into OSS-equipped E-mount lenses, with the body compensating for roll, vertical and horizontal motion while the lens compensates for pitch and yaw, offering better correction than employing just the in-body stabilization. However, for Sony lenses (both A-mount and E-mount) without optical I.S., the camera will provide all the heavy-lifting with sensor-based stabilization (note: some A-mount lenses will only receive 3-axis I.S.) A further benefit is that on third-party lenses, which don't communicate electronically with the camera, users can manually input a focal length (8-1000mm) and thereby get the benefits of the sensor shift stabilization, as well.
Sony A7 II 5-axis SteadyShot INSIDE Image Stabilization Demo
Other changes include an updated grip design, including moving the front sub-control dial into a more natural and convenient front-facing location as well as moving the shutter release button out on top of the grip area. This move has given Sony the space to add an additional "C2" custom function button up to the top deck. The custom function buttons are said to support 56 different function assignments for tremendous customizability. In fact, the functionality of the A7 II can be tweaked quite a bit to suit your shooting style, with the C1-3 custom function buttons, as well as the AEL, ISO, AF/MF, and control dial buttons all being programmable with up to 56 different function assignments.
The body design itself has also received a refresh, with what looks like a matte black speckled finish, a change from the clean, smooth semi-gloss black of the predecessor (and other A7-series models). The body construction is a full two-part magnesium alloy shell that's dust- and moisture-resistant, including weather seals on buttons and dials. The Sony A7II's lens mount has also been improved by using magnesium alloy to increase strength and rigidity, which can be especially helpful when using larger, longer, and heavier lenses.
The Sony A7 II's tiling LCD has also been upgraded to a White Magic panel, which has pixels comprised of red, green, blue and white dots to boost brightness, resulting in a dot count of 1,228,800 versus 921,600 dots for the prior models with RGB panels. The range of the tilting mechanism has also been improved, allowing the panel to tilt upwards to about 107 degrees, up from 84 degrees on the A7, though downward tilt is slightly more limited to about 41 degrees, versus 45 on the predecessor.
First seen on the Sony A7S, the new A7II also features improved video recording capabilities including XAVC S format at 50Mbps as well as an optional S-Log2 gamma profile for maximum dynamic range and more latitude for post production manipulation and grading. There is also time code support, clean HDMI output (up to 1080/60p output) with simultaneous internal recording, as well as uncompressed 4:2:2 8-bit output via HDMI into an external recorder. Video recording resolutions available in XAVC S format are: 1920 x 1080 at 60p, 30p and 24p, while AVCHD 2.0 format offers 1920 x 1080 at 60p, 60i and 24p. 1440 x 1080 and VGA resolutions at 30p are also available in MP4 format.
The Sony A7 II maintains the same 24.3-megapixel full-frame sensor as its predecessor, along with the Fast Hybrid AF system with the combination of 117 on-sensor phase detect points and 25 contrast detect AF points. This allows for up to 5fps burst shooting with continuous autofocus, like the A7 before it, however Sony says AF speed has been improved over its predecessor by some 30% while focus tracking accuracy has been improved by 1.5x through the use of new algorithms for detecting subject distance and predicting motion. Sony also claims the A7 II's startup time is about 40% faster than the A7.
Like its predecessor, the A7 II features both Wi-Fi and NFC wireless connectivity that allow for both wireless transfer of images as well as remote control shooting, among other features using Sony's suite of PlayMemories Mobile apps for iOS and Android devices. Using a special "Lens Compensation" app, A7 II owners can manually adjust the amount of correction applied for various optical characteristics, such as vignetting, chromatic aberration and distortion.
An optional VG-C2EM vertical battery grip that is dedicated to the A7 II is available, allowing a second NP-FW50 battery to double the A7 II's battery life. The A7 II uses the same rechargeable lithium ion battery pack as the original model, and storage is also similar: Secure Digital (SD, SDHC & SDXC) or Memory Stick (PRO Duo, PRO-HG Duo & XC-HG Duo) memory cards. Note: SDXC 64GB memory cards are required to shoot XAVC S format video. The Sony A7II originally began shipping in December 2014 in two configurations: body-only for about US$1,700, or in a kit bundled with the FE 28-70mm f/3.5-5.6 OSS zoom lens (model SEL2870) for about US$2,000. Sony has also introduced a soft carrying case for the A7 II (LCS-ELCB), as well as an FDA-EP15 soft eye-piece cup which is compatible with all Alpha 7 models.
[UPDATE 3/30/2015: To see images shot with the new 24-240mm FE lens go to our A7 II gallery page and scroll to the images with "24-240mm" in the filename.]
Sony A7 II Field Test
One of the best gets better: improved ergonomics, top-notch I.S. and great performance
by William Brawley | Posted 02/20/2015
Sony FE 55mm F1.8: 55mm, f/1.8, 1/125s, ISO 100
Despite some quirks -- slow startup, less-than-optimal ergonomics and limited native lens selection, for example -- the Sony A7-series has been a massive success thanks to outstanding image quality from its full-frame sensor and a small, lightweight form factor. I had a fantastic time reviewing the earlier Sony A7S, and, yet again, notwithstanding a few minor quibbles here and there, the overall experience was impressive. So when Sony surprised the photography world only a year later with the introduction of the second-generation A7 Mark II with built-in sensor-shift image stabilization, I jumped at the chance to shoot with this camera.
The imaging pipeline inside closely resembles the original Sony A7, as it retains the same 24.3-megapixel full-frame sensor and BIONZ X image processor. Despite the similar horsepower, Sony says they've tweaked the AF speed some 30% and improved startup time as well. But they've also made other, more significant changes.
Sony FE 70-200mm F4: 200mm, f/10, 1/400s, ISO 320
Exterior Design & Ergonomics
Let's start with the exterior design first, then work our way inside. Upon first glance, it's apparent the exterior of the Sony A7 II has undergone a subtle but welcomed refresh, mainly around the updated handgrip and repositioned dials. One of my frustrations with the A7S was the rather odd placement of the front control dial and shutter release button. Apparently, I wasn't the only person with this particular gripe, as Sony has thankfully re-designed the handgrip and dial placement on the A7 II pretty much exactly as I had hoped.
The handgrip itself is slightly narrower, but protrudes slightly further out for a deeper and more comfortable hold. Most importantly, the shutter release button is now moved from the top deck down and out front onto the top of the grip itself -- near where the front dial was on the original A7. And the front control dial is now embedded into the front of the grip, similar to a Nikon DSLR. The extra space available now -- by moving the shutter button forward -- has allowed Sony to include another custom function button, which is super handy and allows for even more quick access to settings of your choice to better fit your shooting style.
The Sony A7 II (top) features a deeper, more ergonomic handgrip and a comfortable control layout compared to the original A7 (bottom).
All said, this is an excellent decision by Sony. Now, when I pick up the camera not only does it feel more secure in my hand, but also my grip is comfortable and my index finger is automatically in-place, resting right over the shutter button. The front and rear control dials also have coarser, deeper ridges for easier rotation. The rest of the buttons and dials feel and operate the same as with the previous A7 model, though Sony has replaced the WB (white balance) button on the 4-way rocker with ISO, another welcome change.
The LCD screen, due to the slight extra thickness of the camera body, sits more recessed into the camera when fully "retracted". The panel itself is much thinner than its predecessor's, though. There's no way I'm going to test this, but the durability and strength of the Mark II's LCD screen and hinges certainly feel less sturdy than on the original A7.
The size and shape of the Sony A7 II has changed slightly as well. It looks and feels noticeably heftier and chunkier than the original model. Indeed, to make room for the body-based IS system, the A7 II is thicker than its predecessor, and slightly heavier, too, by about 125 grams. You won't notice it in day-to-day usage though, and it's still significantly smaller and lighter than a full-frame DSLR.
Another part of the A7 II that also got "beefed up" is the lens mount. Like the A7S, the A7 II uses magnesium alloy on both the mount surface and flange for added security, durability and rigidity, which is particularly useful for longer, heavier lenses.
One odd behavior I experience while out shooting with the A7 II is just how sensitive the eye sensor is in the EVF. The sensor is fantastic for shooting with the EVF like a traditional camera. By the time you bring the camera up to your eye, the camera's proximity sensor has almost always triggered the EVF to switch on, and it's ready to use. However, I sometimes want to use the tilting LCD screen to shoot from a different perspective -- particularly when shooting handheld video -- and I found on a number of occasions the proximity sensor would activate the EVF even while holding the camera at what I consider a comfortable distance away from my body -- about a good 5-6 inches. The sensitivity seems rather excessive, and something I didn't experience as often with the A7S. Indeed, when I did a quick measurement with the A7S, I found its EVF activated with a noticeably shorter distance of around 3-4 inches. I'm not sure why Sony made the proximity sensor more sensitive in the A7 II, but as far as I can see, there's no way to adjust the sensitivity, so you'll just have to be aware of this odd quirk.
Lastly, Sony stated that despite maintaining the same processor as the original A7, the startup time on the A7 II has been improved. The A7 II does feel noticeably quicker to power-on and be ready to shoot, and our lab tests confirm this with a 1.7 second startup to first shot time versus 2.1 seconds for the A7. That's still slow compared to most DSLRs, though, but it is improved. The earlier A7-series cameras also displayed an odd behavior whereby turning the camera off and then on again quickly would result in a noticeable -- and often frustrating -- delay. It was as if the camera hadn't finished powering down, so you needed to wait for that process to finish before it would start powering up again. With the A7 II, this has thankfully been remedied to an obvious degree. There's still some delay when doing this quick off-then-on process, but it doesn’t feel excruciatingly slow anymore.
Sony FE 55mm F1.8: 55mm, f/1.8, 1/1000s, ISO 2000
Image quality out of the Sony A7 II is excellent, which isn't surprising considering the stellar performance we found from its predecessor. The 24.3-megapixel, full-frame sensor is capable of capturing fantastic, crisp images with very pleasing colors. Dynamic range is also very good, with great detail retention in shadow areas and as well as highlights. Exposure accuracy was pretty good, though I noticed that in auto white balance for indoor shooting, such as with basketball/gym lighting, that the camera leaned somewhat toward a warmer tone.
Sony FE 55mm F1.8: 55mm, f/1.8, 1/1000s, ISO 2000, Auto White Balance
Sony FE 55mm F1.8: 55mm, f/1.8, 1/1000s, ISO 2000, Fluorescent WB preset
The A7 II handles high ISO shots very well. By default, in-camera noise reduction processing becomes quite noticeable at very high ISOs and is a bit on the strong side for my taste. However, the processing still manages to retain a nice amount of detail. RAW files, on the other hand, look very good at higher ISOs, with very well-controlled noise that's easily tamed or removed with a few slider adjustments in a post-processing application.
Like its predecessor, the A7 II uses Sony's Hybrid AF system -- comprised of contrast-detect AF and on-chip phase-detect pixels -- which Sony claims is around 30% faster than the original model. Using this hybrid system, the A7 II can autofocus very quickly and accurately, with less hunting than cameras with just contrast-detect AF. On well-lit or higher contrast subjects, the A7 II feels like it focuses nearly instantaneously after half-pressing the shutter bottom. In dim lighting, I did notice a tendency for it to focus slower, especially on low-contrast subjects. If I turned off the rather annoyingly-bright AF assist lamp, there were times when the camera simply failed to focus on a poorly-lit, low-contrast subject. Overall, though, the AF performance in single-shot mode feels very quick and an improvement over its predecessor, at least in real-world situations. However our preliminary lab results do not corroborate Sony's 30% faster AF claim, as we measured essentially the same full AF lag as the A7 when shooting our static target multiple times without defocusing between trials using center AF (our standard test). Sony's claim is likely based on specific scenarios or conditions we don't replicate in the lab.
Sony FE 55mm F1.8: 55mm, f/1.8, 1/1000s, ISO 1600
I also had an opportunity to take the A7 II to an NCAA basketball scrimmage. With fast-moving players and the typical indoor gym lighting, I felt the Sony camera also performed really well. Using the Sony 55mm f/1.8 FE lens, the A7 II felt quick and snappy to acquire focus on moving subjects at a variety of speeds. I primarily used continuous AF mode -- which Sony says has been improved 1.5x thanks to new algorithms -- and the camera seemed to keep up with the action well enough that I didn't feel frustrated or felt that I was missing a lot of shots due to focus.
I also tried Lock-on AF, which provides on-demand subject tracking while half-pressing the shutter button. This focus area option is only available if you've switched to AF-C mode (and the camera will alert you if it's in the wrong focus mode). For something as fast-paced and sporadic as basketball, with players and referees moving in and out of frame and in front of other players, this mode was a little difficult to use. But if I found my subject isolated enough, it worked well to track the player in the viewfinder and then time a quick burst of in-focus shots at the right moment. Basketball might not be the best choice for Lock-on AF, but for more isolated moving subjects, say a runner on a track, cycling, or people walking, this subject tracking can come in very handy.
There were a few times when the camera failed to focus properly, resulting in missed shots, but overall, I was pleasantly surprised at how much I enjoyed shooting using the A7 II in a venue such as this. It's difficult to assess an accurate "keeper rate" since sometimes the camera might mis-focus due to a player moving out from behind my focus point too quickly, user error on my part in terms of framing, or the camera indeed couldn't keep up in terms of continuous AF performance. In a selection of about 259 sports shots, I only found around 23-24 frames that were out of focus despite my confidence in the AF point being over the subject.
Both Images: Sony FE 55mm F1.8: 55mm, f/1.8, 1/1000s, ISO 1600
Despite another player moving in front of my intended subject, the Sony A7 II managed to keep focus locked on this more distant subject in these two successive frames.
I would still prefer a good DSLR for shooting something like high-intensity sports and action, as the AF performance is still superior at this point in time. Also, while the 5fps continuous mode burst rate is decent for its class, that burst rate is rather paltry compared to pro-level DSLRs and even some enthusiast-level/prosumer DSLRs (as well as other some other mirrorless cameras). However, to be fair, the A7 II is not really geared as a sports camera, and even some similiarly-priced full-frame DSLRs, like the Canon 6D for example, have slower burst rates. If your shooting style is not synonymous with a machine gun, then a solid 5fps burst might be all you need. Furthermore, the buffer capacity of the A7 II is impressive for its class. The IR lab found the A7 II to chew through 52 Extra Fine JPEGs and 24 RAW+JPEG pairs before the buffer filled. This isn't a significant improvement over the A7, but it bests a number of competing 24MP full-frame DSLRs. All in all, for the times when you need to capture shots of moving subjects, the Sony A7 II is able to offer very acceptable performance for both AF and burst shooting.
Of course, the big story with the Sony A7 II is the built-in sensor-shift image stabilization. This isn't Sony's first full-frame camera with sensor-shift stabilization; that award goes to the A900 DSLR (the world's FF camera with sensor-shift stabilization, in fact) going dating back to 2008, followed by the A850 in 2009 and SLT A99 in 2012. However, the A7 II is indeed the world's first 5-axis-stabilized full-frame mirrorless camera.
A handheld shot at 24mm with a 1/4s second exposure time is great example of the A7 II's I.S. chops!
Sony FE 24-70mm F/4 OSS lens: 24mm, f/4, 1/4s, ISO 5000
The A7 II's "SteadyShot INSIDE" systems works in different ways depending on which lens is used. For Sony FE-mount and most APS-C E-mount lenses with optical image stabilization, the A7 II will off-load some of the stabilization work to the lenses to achieve optimal results: Pitch and Yaw corrections handled by the lenses and Roll, X- and Y-directional corrections performed by the sensor.
A macro shot with the Sigma 70mm Macro A-mount lens + adapter.
70mm, f/5.6, 1/60s, ISO 800
There's a another trick up the Sony A7 II's sleeve: you can also have image stabilization with practically any brand of lens, new or old, so long as you have an adapter to mount it to the camera. This means classic vintage lenses, Leica lenses and even Nikon and Canon glass can be adapted to the A7 II and benefit from 5-axis image stabilization. In the camera menu, you simply switch to manual SteadyShot, and select the appropriate focal length (from 8mm to 1000mm), which tells the camera how much correction to apply.
I found the image stabilization to work very well on the A7 II, with both Sony FE lenses and an adapted A-mount Sigma 70mm macro lens. Shooting handheld in low light and intentionally using slower shutter speeds, the image stabilization system produced noticeably sharper images than without I.S. For example, using the FE 70-200mm f/4 lens, I was able to capture sharp photos at around an impressively slow 1/20th of a second at 200mm! (Note that I upgraded to firmware v1.10 for my image stabilization tests, since I.S. was said to be enhanced by that release.)
The video recording capabilities of the Sony A7 Mark II gained some notable improvements over its predecessor, sharing a host of features from the earlier A7S...minus 4K recording. Sony added the 50Mbps XAVC S format, Picture Profile support including SLog2 gamma, time code and clean HDMI output up to 1080/60p with simultaneous internal recording and uncompressed 4:2:2 8-bit output.
Sony A7 II Sample Video #1
1,920 x 1,080, XAVC S, Progressive, 60 fps
Download Original (160.1MB MP4)
Sony A7 II Sample Video #2
1,920 x 1,080, XAVC S, Progressive, 60 fps
Download Original (160.5MB MP4)
Using the IR Lab's Still Life target, I did a quick comparison test to judge the image quality difference between the A7 II's 50Mbps XAVC S and the A7's 28Mbps AVCHD video format. I found the difference in image quality to be surprisingly subtle. In some areas, very fine detail looked slightly better on the A7 II, and using the same manual exposure settings, the A7 II displayed slightly more detail in the shadows at default picture/image profile settings.
Sony A7 II Still Life Detail Video
1,920 x 1,080, XAVC S, Progressive, 60 fps
Download Original (296.1MB MP4)
Sony A7 Still Life Detail Video
1,920 x 1,080, AVCHD, Progressive, 60 fps
Download Original (163.5MB MTS)
Of course, the big feature with the A7 II is its image stabilization system, and this works for video as well. In some short outdoor testing, both walking and stationary, I found the combination of sensor and lens I.S. (using the FE 24-70 F4 and FE 70-200 F4 lenses) worked very well for stationary, handheld shots, but for walking shots, it was a different story. For my walking tests -- using the 24-70mm F4 lens -- I could not see much improvement with IS enabled. I believe the amount of shaking and movement was too much for the IS system to correct, at least at the rather quick pace I was moving. However, for stationary, handheld shots -- using the longer Sony lens at 200mm -- the IS system on the A7 II dramatically calmed and smoothed out shaky, vibrating video.
Now adding a fourth option to its lineup of full-frame mirrorless cameras, I think Sony has yet another winner on their hands. By addressing some of the design quirks of the original model, as well as providing a notable technological achievement with their 5-axis image stabilization -- and some subtle, yet worthwhile, performance enhancements -- the Sony A7 II is a more matured, more well-rounded camera.
Sony FE 55mm F1.8: 55mm, f/1.8, 1/60s, ISO 500
My only significant reservations about this camera don't necessarily relate to the camera itself, but rather the lenses. The native Sony FE-mount lens lineup, as we've pointed out in our previous reviews, is still rather thin. If you need ultra-wide, super telephoto or mid-range zooms with fast apertures, the world of adapters awaits you, either for Sony's A-mount lenses or other brands of glass.
Nonetheless, for those wanting a full-frame camera that offers a great balance of performance, high-resolution and high-quality images, built-in image stabilization, but still in a compact design, look no further than the Sony A7 II. In fact, you can't look elsewhere; the Sony A7 II is rivalless for this combination of features and qualities, unless you opt for a DSLR or SLT-style camera.
Sony FE 24-70mm F/4: 70mm, f/4, 1/320s, ISO 100
Sony A7 II Image Quality Comparison
The A7 got high marks here, can the 'Mark II' do it again?
NOTE: These images are best quality JPEGs straight out of the camera, at default settings including noise reduction and using the camera's actual base ISO (not extended ISO settings). All cameras in this comparison were shot with our very sharp reference lenses. Clicking any crop will take you to a carrier page where you can click once again to access the full resolution image as delivered straight from the camera. For those interested in working with the RAW files involved, click these links to visit each camera's respective sample image thumbnail page: Sony A7 II, Sony A7, Canon 6D, Fujifilm X-T1, Nikon D610 and Samsung NX1 -- links to the RAW files appear beneath those for the JPEG images, wherever we have them. And remember, you can always go to our world-renowned Comparometer to compare the Nikon D750 to any camera we've ever tested.
Sony A7II Print Quality
Let's go pixel-peeping in the real world!
Sony A7 II Conclusion
Are the A7 successor's new features worth the upgrade?
The big change, however, is that Sony took this large full-frame sensor and added sensor-shift image stabilization. The A7 II is the world's first 5-axis image stabilization system in a full-frame mirrorless camera. Sony claims the IS system will provide up to 4.5 stops of correction, and the system is also designed to work in concert with Sony's optically-stabilized glass when such lenses are used. We found the A7 II's "SteadyShot INSIDE," as Sony calls it, works very well, for both stills and stationary, handheld video. For run-and-gun video, or other video with lots of camera movement, however, the IS system did not show significant improvement over non-stabilized footage. But, for stills, especially low-light and macro photography, or video shooting without a tripod, the 5-axis IS system was very impressive.
In the Box
The Sony A7 II body-only retail box (as reviewed) contains the following items:
- Sony A7 II camera body
- NP-FW50 Lithium-Ion Rechargeable Battery (1020mAh)
- AC-UUD11 AC Battery Charging Adapter
- Shoulder Strap
- Body Cap
- Multi-Interface Shoe Cover
- Eyepiece Cup
- Micro-USB Cable
The Sony A7 II is also offered in a kit configuration with the FE 28-70mm f/3.5-5.6 OSS lens, which includes all other items as listed in the body-only retail package above.
- Large capacity SDHC/SDXC memory card. (SDXC memory card required for XAVC S video format.)
- Extra NP-FW50 Lithium-Ion Rechargeable Battery (~US$50)
- Sony Vertical Battery Grip for Alpha a7 II Digital Camera (~US$350)
- Sony HVL-F20M External Flash (~US$148)
- Small/Medium Carrying Bag
Buy the Sony A7 II
$4342.72 (68% more)
Also has viewfinder
$7595.00 (82% more)
Also has viewfinder
$1149.00 (22% less)
Also has viewfinder