Sony Alpha 7R review – Noise, resolution and sensitivity
There have been only a handful of cameras that have completely outresolved our resolution chart. Although the recent Pentax K-3 and Nikon D5300 came very close, only the Nikon D800 and D800E DSLRs, along with the Pentax 645 and Hasselblad H4D-40 medium-format cameras, have done it with ease. The Alpha 7R can now be added to that list. All the lines at the end of the chart are clearly visible, and they remain so until the very highest sensitivities are reached, even in JPEG files.
Noise is reasonably well controlled. There are some signs of luminance in raw and JPEG files at ISO 800, but this isn’t an issue unless you are looking at images at 100%. By ISO 1600 there is a little more luminance noise, and colour noise is visible in shadow areas on JPEGs. This is easily removed when editing raw images and, again, the resolution means that even when making reasonably large prints it shouldn’t prove to be detrimental.
One thing that could be improved is the JPEG processing. The intelligent noise reduction and associated sharpening that analyses the scene and edits the image accordingly can look a little artificial when viewed at 100%. At lower magnifications it isn’t really visible. I would prefer a slightly more universal colour noise and luminance noise reduction for an even finish.
As photographers have discovered with the D800, and more notably the D800E, it is vital that images are focused precisely and camera shake is reduced as much as possible. Obviously, the camera shake is often no different than when using any other camera, but the high resolution does magnify the situation when looking at images at 100%. However, this didn’t mean that I couldn’t take extremely sharp images handheld. It is important to shoot at a suitable shutter speed, even with image stabilisation. I found that I generally shot around 1EV faster than I would normally have to with a DSLR and a lower resolution. Again, the key is to learn how to use the camera to get the best from it.
With any new line of cameras, the lens line-up is important. I had the opportunity to try the FE 28-70mm f/3.5-5.6 OSS lens, which is the kit lens for the Alpha 7, the Zeiss Sonnar T* FE 35mm f/2.8 ZA and Zeiss Sonnar T* FE 55mm f/1.8 ZA lenses. The fixed lenses are extremely sharp in the centre, with some slight fall-off in sharpness towards the edges of the frame with the 35mm lens. However, the 28-70mm f/3.5-5.6 lens is disappointing. It shows a sudden and significant drop-off in sharpness at the edges of the frame at the 28mm setting.
I also used a Canon 24mm f/2.8 lens, via a Metabones adapter, and found the lens to be very good at the corners, with images looking full of detail and very sharp. However, the lens is designed for the longer flange back of the Canon EF mount. To manufacture a very good wideangle lens, smaller lenses may have to be sacrificed for larger wideangle lenses that produce sharper results. I am eagerly awaiting the Zeiss Vario-Tessar T* FE 24-70mm f/4 ZA OSS lens to see how well it works with the Alpha 7 cameras. The lens is due out shortly and we hope to test it early next year. A macro, wideangle and another wide-aperture prime lens are also due for release towards the middle of 2014.
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using the Carl Zeiss 35mm f/2.8 lens set to f/5.6 . We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
