Hand-held Twilight Mode
Handheld Twilight mode isn't a new function, but it is one which we have found very useful, in the SLT-A77 and other recent Sony cameras, both compact and interchangeable lens models. In this mode, accessible through the 'Scene' menu on the exposure mode dial, the camera takes several exposures at its highest framerate, then blends them together in-camera to reduce the impact of high ISO noise. Although pixel-level sharpness isn't great, handheld twilight mode is a quick, easy and (usually) effective way of grabbing a smooth and colorful shot in conditions where normally you'd need to use either a high ISO sensitivity setting or a tripod. Compare the areas of plain tone in this scene, below, captured hand-held at ISO 800 and again in handheld twilight mode.
|ISO 800, f/4.5, 1/100sec||100%|
|Handheld Twilight mode||100%|
The SLT-A77 includes an automatic sweep panorama mode that allows you to create large, high-resolution panoramas in-camera. The auto-stitch mode does a very good job of hiding stitches and in general creates consistent tones, as long as there is no significant subject movement for the duration of the pan.
In common with our experience of this mode in other recent Sony cameras Sweep Panorama works very well, and creates usefully high-resolution files compared to the same function in Sony's Cyber-shot models, which stitches panoramas together from the camera's video feed. The ease of use and automated stitching come at a price however. Stitching errors can be an issue (look at the ship on the horizon towards the left-hand side of our twilight shot, above).
When creating a panorama of a scene with a large dynamic range it is best to start the shot in the darkest area. The exposure is retained from the first shutter press and if the first image is too bright, the panorama tends to not complete at all, especially if the sweeping motion is too fast or inconsistent.
DRO and HDR
Dynamic range optimization (DRO) is creating a single image containing a large range of brightness in a way that looks natural to the human eye. DRO applies a series of tone curves to each area of similar local brightness within a single image, in an attempt to balance details in the shadows while maintaining local contrast. For a more in-depth explanation of how the system works please take a look at our 2009 article about the technology behind DRO.
Auto HDR is only available in JPEG mode, and allows automatic exposure bracketing up to 6EV. The final HDR images are achieved by combining multiple exposures (one normally exposed, one over exposed and one under exposed.) This allows for a larger dynamic range to be recorded than the sensor is capable of capturing alone. When shooting in HDR mode the camera saves the HDR image along with the normally exposed image. Sony's HDR and DRO features are covered in more detail in our NEX-C3 review.
|DRO Off||50% crop|
|DRO Auto||50% crop|
|HDR - Level 6||50% crop|