Sony Alpha SLT-A55V: Video and Image Quality

Video Quality
The a55 can capture video in the AVCHD format at 1920x1080i resolution; MP4 at 1440x1080 or 640x480 resolutions. Maximum clip length is 29 minutes in either format. AVCHD is recommended for viewing on HD television with MP4 suggested for internet use. Our sample video is MP4. While AVCHD is becoming more common, viewing requires an AVCHD-compatible device while the MP4 format is more universally recognized at this point. That will be a stumbling block in trying to share your AVCHD clips with friends without AVCHD compatible equipment.

Sony points to quick AF in movie mode as one of the benefits of the translucent mirror design of the a55, and the camera was quick to transition into movie mode and focus - one of the quickest video-capable still cameras I've reviewed. Another bonus is the ability to use the viewfinder for video capture. Zoom is available while capturing video and the microphone can be sensitive to wind noise. It also picks up noise from the camera when it auto focuses on a changing scene and establishes a new focus point. With a CMOS sensor, rolling shutter effect is in play during panning, but the effect is fairly well controlled in the a55 and requires exaggerated pan speeds to produce objectionable effects. Image quality was good, and the video component overall was one of the better ones I've reviewed.

Image Quality
Default images out of the a55 were good. Colors were accurate and perhaps a bit more saturated than in real life but pleasing and nicely sharp. There are contrast, saturation and sharpness settings that range from -3 to +3 in for manual shooting modes in the event the default settings don't meet user expectations.

The 16 megapixel sensor provides for files that take some cropping and still produce decent quality prints. The first image is the original shot; the image below it was sized to 12x8 inches and retains a 223 dot per inch density that will produce a good quality print.

Sony's color palette options will be familiar to Sony users. Here are the standard, vivid, portrait, landscape, sunset and black & white modes.

Standard	Vivid
Portrait	Landscape
Sunset	Black & White

The a55 offers DRO (D-Range Optimizer) and HDR (High Dynamic Range) settings that may be enabled to enhance the camera's apparent dynamic range. DRO "...divides the image into small areas and the camera analyses the contrast of light and shadow between the subject and the background, producing the image with the optimal brightness and gradation." HDR "Shoots three images with different exposures, and then overlays correctly exposed image, the bright areas of an under exposed image and the dark areas of an over exposed image to create an image with rich gradation. Two images are recorded: an image with the correct exposure and an overlaid image." Here's a motorcycle with and without DRO enabled.

DRO Off

DRO Auto

Both DRO and HDR have automatic and manual settings; DRO offers five levels of strength, HDR offers six.

Auto white balance was used for the shots in this review and worked well under a variety of light sources, but shot warm under incandescent light. The a55 offers daylight, shade, cloudy, incandescent, fluorescent, flash and custom settings, along with a color temperature option that allows you to designate a Kelvin temperature for your lighting conditions.

Auto White Balance, 5500k fluorescent light

You can view the scene through the viewfinder or on the monitor as you adjust temperatures until they look right to you. Here's another one-handed shooting job with incandescent light and auto WB, along with one where I dialed in temperature until the colors looked "right". Focus was on the figurine for one and Simon on the other, but the color correction is unmistakable.

Auto	Temperature Adjusted

Multi-segment metering was used for this review, but there are center-weighted and spot options available. The a55 lost highlights on occasion in high contrast situations, but exposure compensation is available in manual shooting modes.

The a55 has a nominal ISO range from 100 to 12800. ISO 100 and 200 were hard to differentiate and for all practical purposes equal. ISO 400 picked up just the slightest bit of some graininess in isolated spots, but was very hard to tell apart from 200, particularly in smaller images. ISO 800 seemed to mirror 400 with colors being a bit less saturated. Images at ISO 1600 seemed softer overall than 800, with some loss of clarity in fine detail areas.

ISO 100	ISO 100, 100% crop
ISO 200	ISO 200, 100% crop
ISO 400	ISO 400, 100% crop
ISO 800	ISO 800, 100% crop
ISO 1600	ISO 1600, 100% crop
ISO 3200	ISO 3200, 100% crop
ISO 6400	ISO 6400, 100% crop
ISO 12800	ISO 12800, 100% crop
ISO 25600	ISO 25600, 100% crop

ISO 3200 seemed a bit softer again in fine detail areas, and colors that again seemed a bit less saturated. ISO 6400 seemed grainier with another loss in fine detail areas, and 12800 was much grainier, with fine details turning into smudges and much less intense color. Overall, on darker subjects the jump from 1600 to 3200 seemed to be where noise took its toll; lighter objects took their hit from the 3200-6400 increase. None of the ISOs look too bad in small images, and while the a55 hasn't re-written the book on ISO noise performance for DSLRs, its latest-generation sensor and processor seem to do a good job at this resolution level.

Ah, but just when you think you've heard it all on ISO noise, the a55 whispers in your ear "what about Multi Frame Noise Reduction (MNR)?" Seems that in the ISO settings there are "auto" and "auto ISO" options. Selecting "auto ISO" gets you MNR which rapidly captures 6 images to create a single image with lower noise. MNR goes from 100 to 25600 ISO. Capture time took a bit over 3 seconds in moderate light at 100 ISO; that time dropped to about 1.25 seconds in dimmer light at 25600. Hand holding seemed to produce decent results regarding camera shake with stationary and slow-moving subjects, but a stationary subject and camera support would be good options when possible. Here's 3200 through 12800 in regular ISO and MNR, plus 25600MNR, as well as 200 and 200MNR.

ISO 200	ISO 200 MNR
ISO 1600	ISO 1600 MNR
ISO 3200	ISO 3200 MNR
ISO 6400	ISO 6400 MNR
ISO 12800	ISO 12800 MNR
ISO 25600 MNR

Not much to choose from between the 200s, but the higher ISOs in dim conditions favor the MNR shots. MNR has a fairly narrow window of opportunity because of the stationary subject/camera shake concerns, but if circumstances permit it looks like a viable way to go if you have to ramp up the ISOs.

Additional Sample Images