Sony Alpha 99 (SLT-A99V): Sony introduces the Alpha 99 (SLT-A99) full format camera: 35mm device with electronic viewfinder

The core of the SLT-A99 introduced from Sony, is a newly developed sensor in 35mm format with a resolution of 24 megapixels. With the SLT-A99, Sony is also introducing a number of innovations in the professional segment. These include a high-resolution electronic viewfinder, the dual AF system including phase AF sensors on the image sensor, and an ISO hot shoe with additional contacts for special system accessories. The SLT-A99 is also aimed specifically at videographers and is available since January 2013.

Brief assessment

Pros

• Electronic focus limiter
• Fast tracking AF, even when recording video
• Excellent image quality
• Excellent handling and ergonomics

Cons

• Very high continuous shooting rates only with nonsensical digital zoom
• Cover of the card slot creaks
• No on-board flash
• AF fields too restricted to image center

With the SLT-A99, Sony is trying the big leap forward. The 35 mm camera finally offers everything that fans of the full format have had to do without at Sony until now; live view and video recording, for example. In addition, there is a completely new AF system with 102 phase AF fields on the image sensor, as well as an innovative operating aid. What’s revolutionary is that for the first time in a full-frame camera, Sony has dispensed with a conventional optical viewfinder – the A99 always shows the viewfinder image in live view mode on the display or in the electronic viewfinder.

In the hard practical application “on location” and in the studio we then pursued the probably most exciting question: Can the SLT concept with an exclusively electronically generated viewfinder image also convince with a full format camera?

Ergonomics and Workmanship

Equipment

Lens

Currently, the A99 is only offered “body only”, i.e. not in a set with one lens. I have tested Sony’s new full format flagship with the 24-70 mm 2.8 Vario-Sonnar T* ZA SSM, which would also cut a fine figure as a set lens for the A99. The standard zoom looks as if it has been built to last for eternity – which is certainly not least due to its considerable weight of 995 grams. The lens adjusts the focus with a quiet SSM drive, so there is no need for an optical image stabilizer: As usual with Sony, the A99 also has a sensor-shift stabiliser – a movable image sensor compensates for the shaking of the photographer’s hand. The advantage of this method is that the image stabilizer is available with practically any lens. Theoretically it would even be possible to create a stabilized viewfinder image. However, Sony does without this option, the stabilizer only comes into action when the shutter button is pressed all the way down.

Although the A99’s image sensor always provides a live view viewfinder image, Sony continues to use classic phased autofocus to determine subject distance. This module is somewhat sparingly equipped with 19 sensors, eleven of which are cross sensors. It receives around 30 percent of the incident light from a partially transparent mirror that is firmly anchored in the beam path (but can be folded up manually for sensor cleaning). For the first time in an Alpha family camera, the A99’s image sensor also assists in focusing: Sony has placed 102 phase AF cells on the image converter to provide the autofocus system with additional information. This allows the A99 to focus faster and, above all, more accurately. However, the new AF-D mode currently only works in conjunction with some lenses, including the 24-70/2.8.

Also new on the A99 is an electronic focus limiter. It can be used to specify that the camera should only focus within a certain distance range. This prevents the A99 from focusing on the bars in the foreground, even though the lion further back in the enclosure should be in focus. According to Sony, this focus limiter also only works with selected, newer lenses, but in the test it performed its service without complaint even with a quite old Minolta 50 mm 1.4 mm. Even without a focus limiter, the autofocus of the A99 proved to be quite fast in the test lab: In the best case, only 0.2 seconds passed until the camera had focused and triggered.

In practice, however, it was annoying that Sony apparently took over the A99’s AF module from the APS-C sister, the A77. On the A99, for example, it covers only about 1/9 of the much larger image area in the center. Even the 102 additional focus detectors on the image converter do not help here, they are also arranged within the manageable central area. The fact that Sony has undoubtedly jumped short here is impressively demonstrated when face recognition is activated: it frames a face without much feather-reading, even if it’s far at the edge of the picture frame. However, the AF focuses on an area within the image center, since there are no measuring fields in the outer areas.

Image quality

While Sony has been a pioneer in terms of maximum resolution up to now, the A99 makes smaller leaps here – it remains at around 24 megapixels, just like its predecessor. This almost conservative design for a full format camera need not be a disadvantage. 24 megapixels are sufficient for prints in the format 51 x 34 cm at a print resolution of 300 ppi – or in other words: at least for A3+. The moderate resolution leaves more space for the individual sensor cells, they can be larger and thus become more light-sensitive. Sony has also revised the design of the image converter, with the converging lenses in front of each pixel moving closer to the light-sensitive layer and also focusing more strongly than before – in short, the A99’s sensor is more light-sensitive than its predecessor.

The laboratory report certifies that the A99 has a signal-to-noise ratio almost like in a textbook: In the brightness channel it remains at a very high level of over 40 dB up to ISO 400 and only falls below the critical limit of 35 dB beyond ISO 3,200. In relation to the color information, the signal-to-noise ratio is somewhat less favorable, but far from a reproach. It is also outstanding that the grain never reaches a critical size up to ISO 25,600 – apart from an outlier in the red channel. Thus, the noise always remains very fine and, if at all, is only visible (but by no means disturbing) beyond ISO 6.400. ISO 6.400 is also the limit above which noise reduction sacrifices the finest image details for the first time perceptibly. But even up to the ISO upper limit of 25,600, the texture loss due to noise reduction is extremely low. Not only metrologically, but also in practice, the A99’s high-ISO capabilities can leave no one hands-empty: When the photographer’s hangover jumped onto the setup in the studio’s sparse modeling light, the A99 had no trouble reproducing the finest hairs and nuances in the coat even at ISO 3,200.

The input dynamics of the A99 are excellent: the camera processes a contrast range of 10.5 f-stops and more up to ISO 1,600; even at ISO 12,800, the laboratory report shows a dynamic range of 9.1 EV – superb! The output tonal value range is also at the highest level; up to ISO 400 it is close to the theoretical maximum and only falls below the critical limit of 7 bits/channel beyond ISO 6,400. As with the measurement of grain size, however, the red channel is the key issue here – the camera differentiates red tones somewhat poorly from a metrological point of view, but this is by no means visible. With so much praise, you have to search meticulously to find any point of criticism at all. Maybe with the color fidelity, the average color deviation might be a little less, although it never becomes critical.

With the new 24 megapixel sensor and the image processor, Sony has undoubtedly made a big leap forward. But what about the image quality when the 24-70 mm 2.8 Vario-Sonnar T* ZA SSM lens comes into play? After all, it proudly bears the “Zeiss” label, and the tradition-rich company Carl Zeiss gives Sony a great deal of support in the development and manufacture of the lens. And apparently it was not a bad decision of the Japanese to get advice and help from this German optics leader manufacturer: The zoom is characterized by a high sharpness at all focal lengths, and this over the entire field of view of a 20 x 30 centimeter pint. In addition, it convinces with a very even brightness distribution; even with an open aperture it darkens the image corners only minimally. The lens is not quite as flawless when it comes to chromatic aberration: On average, color fringes are only very faint and remain invisible, but they can be quite annoying, especially in the wide-angle range. However, the Carl-Zeiss lens is somewhat weaker in terms of resolution: Although it achieves a maximum resolution of a good 45 line pairs per millimeter (lp/mm) in the center of the image, comparable lenses from other manufacturers are even better. In addition, the loss of resolution is somewhat pronounced towards the edges of the image. Overall, the imaging performance of the lens is more than okay, but the full potential of the camera can only be exploited with high-quality fixed focal lengths.

Conclusion

Sony made a big leap forward with the SLT-A99. The electronics giant is taking its SLT concept to new heights with its always electronically generated viewfinder image in the full-format camera. Despite all the prophecies of doom (and reviews of pre-production models, that were inferior to this one we tested now for this article), the A99’s electronic viewfinder is a knockout; the resolution is fine down to the last detail, and the significantly improved EVF allows for the first time an exact assessment of contrasts even before shooting. Sony is also breaking new ground with the operating concept, with the smart rotary control on the front making handling even easier. The image quality of the A99 is beyond doubt – up to high ISO 3,200, the camera delivers images that can be printed in poster size. The equipment is almost complete, but at least rudimentary image processing functions in playback mode would be desirable.

However, Sony clearly falls short in the A99’s autofocus – despite all the innovations: The measuring fields only cover a very narrow area in the center of the image; Sony should have been happy to refrain from this economy measure in view of the price of the A99. When it comes to video recording, the A99 is ahead of the game, not least thanks to its constantly active phase AF. If you want the best is just good enough for you, you can confidently reach for the A99 – if you can do without focus points at the edges of the picture.