Sony Alpha SLT-A77: Hand-held Twilight vs Aperture Priority mode at 500 ISO

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Sony SLT-A77 results 1 Sony SLT-A77 Quality 2 Sony SLT-A77 RAW vs JPEG 3 Sony SLT-A77 Noise 4 Sony SLT-A77 Handheld Twilight 5 Sony SLT-A77 Sample images

The Alpha SLT-A77 inherits the Handheld Twilight mode from recent Sony cameras. This fires-off six frames in quick succession and stacks them into a single image in an attempt to lower noise levels. On this page I've put the SLT-A77's Handheld Twilight mode to the test. This automatically selects the sensitivity so I've compared it against the closest manual ISO. You can see a set of results for the Multi-frame Noise Reduction option lower on this page.

The above shot was taken with the the Sony Alpha SLT-A77 using Hand-held Twilight mode.The camera automatically selected an exposure of 1/60 at f4 with a sensitivity of 500 ISO and the original file measured 10.38MB. For the comparison, I switched to Aperture priority mode and selected f4 at 500 ISO and the camera metered the same 1/60 exposure.

As we saw from the high ISO noise tests, 1600 ISO is the point at which the NEX-7 starts to exhibit quite visible and intrusive noise that affects medium sized image detail. At 500 ISO the SLT-A77 in Hand-held Twilight mode produces results that are a marginal improvement on the single-shot 500 ISO crops, but you have to look very hard to spot it. It's most visible in the first crop where if you look at the shadow area on the right of the crop you'll see it looks a little textured and clumpy in the bottom crop from the Aperture priority shot wheras the top hand-held Twilight crop looks smoother. But at anything other than 100 percent view you'd never be able to spot the difference. Hand-held Twilight mode really comes into its own at ISO sensitivites of 1600 and above, where the SLT-A77's sensor really starts to stuggle with noise suppresion on single-shot images.

Alternatively you can manually select the ISO in Multi-frame Noise Reduction, and I have a set of results for you lower on this page.

Sony Alpha SLT-A77: Handheld Twilight mode at 500 ISO
f4, 1/60,500 ISO		f4, 1/60, 500 ISO		f4, 1/60, 500 ISO

Sony Alpha SLT-A777: Aperture Priority at 500 ISO
f4, 1/60, 500 ISO		f4, 1/60, 500 ISO		f4, 1/60, 500 ISO

Multi Frame Noise Reduction

The SLT-A77includes the Multi Frame Noise reduction feature introduced on the SLT-A33. This fires-off six frames in quick succession and stacks them into a single image in an attempt to lower noise levels. The big difference to Hand-held Twilight is Multi Frame Noise Reduction can be applied at any sensitivity (including a 25,600 ISO setting) and in any of the PASM modes. Below I've put it to the test, comparing it against the normal single-frame ISO settings.

The crops below show the results from my single exposure high ISO tests on the left. For these tests the camera was placed on a tripod and image stabilisation and tonal adjustments were disabled. The SLT-A77 metered an exposure of 1/5 at f5.6 at 100 ISO. Shorlty after these shots were taken I selected Multi Frame noise reduction mode and made a further sequence of exposures at each of the ISO settings, plus the 25,600 ISO setting for comparison. For the 100 ISO shot the SLT-A77 metered the same exposure in Multi Frame Noise reduction mode - 1/5 at f5.6.

These crops make for some interesting comparisons. While you wouldn't want to use Multi Frame Noise Reduction in all circumstances, the higher the ISO sensitivity setting the more effectively it outperforms a single frame shot in terms of noise reduction and overall quality.

Below 800 ISO the Multi Frame Noise reduction crops are no better and in most cases worse than the single frame crops with visible softening of fine and medium sized detail. 800 ISO is the tipping point, the detail is slightly softer, but the noise is significantly reduced. And at 1600 ISO and above the Multi Frame Noise reduction crop is, it's no exaggeration to say, a massive improvement.

Now head over to my A77 sample images to see some more real-life shots in a variety of conditions.

Sony Alpha SLT-A77 (JPEG using in-camera defaults) with Sony SAL 1650 SSM		Sony Alpha SLT-A77 (Multi Frame Noise Reduction) with Sony SAL 1650 SSM
50 ISO		50 ISO Not available
100 ISO		100 ISO
200 ISO		200 ISO
400 ISO		400 ISO
800 ISO		800 ISO
1600 ISO		1600 ISO
3200 ISO		3200 ISO
6400 ISO		6400 ISO
12800 ISO		12800 ISO
16000 ISO		25600 ISO