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Sony Alpha SLT-A33 Gordon Laing, February 2011

Sony Alpha SLT-A33 results : Real-life resolution / High ISO Noise / Handheld Twilight (HHT) / Multi-frame NR / HDR


Sony Alpha SLT-A33 vs Canon EOS 550D / Rebel T2i Real-life resolution (default settings)

 
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To compare real-life performance we shot the same scene with the Sony Alpha SLT-A33 and the Canon EOS 550D / T2i within a few moments of each other using their best quality JPEG settings and base sensitivities.

Each camera was fitted with its respective kit lens: the A33 with the SAL1855 SAM and the 550D / T2i with the EF-S 18-55mm IS. Each lens was set to f8 in Aperture Priority and adjusted to deliver the same field of view.

The image above was taken with the Sony Alpha SLT-A33 at 100 ISO with an exposure of 1/320 and the lens set to 24mm f8; the original Large Fine JPEG measured 6.56MB. The Canon EOS 550D / T2i metered 1/250 at f8 / 100 ISO for the same scene moments later, but we took an additional shot at 1/320 / f8 / 100 ISO to see which was the closest match to the Sony in terms of brightness. The matching exposure turned out to be a little darker than the original A33 image, while the 1/250 version was almost identical. This implies the A33 is approximately 0.25 to 0.33EV more sensitive than the EOS 550D / T2i when both were set to 100 ISO.

The crops below are taken from the areas marked with the red squares and presented here at 100%. The crops from the EOS 550D / T2i show a smaller area due to its higher resolution: 18 Megapixels versus 14.2 on the Sony.

Looking at the numbers you'd assume the four extra Megapixels of the Canon EOS 550D / T2i would give it a significant advantage in terms of real-life detail, at least at the lowest sensitivity. Judging from the crops below though, that's clearly not the case. The higher resolution Canon image has certainly delivered smaller areas in the crops, but there's no perceptible advantage in resolved fine detail. Indeed in some of the crops, the Canon images appear noticeably softer than those from the Sony.

The problem here is not the Canon's sensor, but the EF-S 18-55mm IS kit lens, which just isn't resolving sufficient detail to exploit the high resolution behind it. Worse, this lens exhibits softness and fringing towards the corners, which is apparent in the first and fourth crops, where the quality falls below that of the Sony. Fit any of the Canon 18 Megapixel bodies with a higher quality lens and it's a different story. For example, go for the EF-S 15-85mm IS USM or EF 24-105mm IS USM and you'll find the sensor resolving finer details, while better avoiding the corner softening seen here.

Revealingly though, we don't have to make any such excuses for the Sony. Sure there's better lenses in the Alpha range, but we like to test budget and mid-range DSLRs with the lenses they're most likely to be sold with, and that means the basic kit models. In this scenario, the SLT-A33 delivers sharp and detailed results which match the Canon EOS 550D / T2i 18-55mm kit in the middle of the frame and exceed it towards the corners.

It's a valuable lesson that Megapixels don't tell the whole story when it comes to quality. Give the Canon 18 Megapixel bodies a decent lens (as you can see in our EOS 60D and EOS 7D reviews) and they will resolve lots of detail, but fit them with the EF-S 18-55mm IS kit lens and you should expect results closer to a 14 Megapixel model. So the surprise result here is the Sony SLT-A33 kit matches and in some respects out-performs the EOS 550D / T2i kit at 100 ISO, when both are fitted with their respective 18-55mm lenses.

Scroll down to see if there's any benefit to shooting in RAW with the A33, or skip straight to our low-light results, which start with a High ISO Noise comparison, again against the EOS 550D / T2i.


Sony Alpha SLT-A33 (JPEG using in-camera defaults)
with Sony SAL1855 SAM
 
Canon EOS 550D / T2i (JPEG using in-camera defaults)
with Canon EF-S 18-55mm IS
f8, 100 ISO
f8, 100 ISO
     
f8, 100 ISO
f8, 100 ISO
     
f8, 100 ISO
f8, 100 ISO
     
f8, 100 ISO
f8, 100 ISO




Sony Alpha SLT-A33: JPEG versus RAW


We photographed the scene above using the SLT-A33's RAW plus Large Fine JPEG mode, allowing us to directly compare images created from exactly the same data. Below are crops taken from the original JPEG file alongside the RAW version, processed in the supplied Image Data Converter SR 3.2 using the default settings.



Judging from the crops below, there's not much to choose between the in-camera JPEG and the RAW file processed with Image Data Converter using the default settings. The crops look almost identical, with only very subtle differences in sharpness and saturation.

Of course tweaking the settings may deliver superior results, and shooting in RAW gives you greater flexibility when it comes to retrieving highlight detail and adjusting White Balance, but it's reassuring to find the in-camera JPEG engine of the SLT-A33 delivering such good results.

We're now going to delve into low light performance, starting with our Sony A33 High ISO Noise comparison.


Sony Alpha SLT-A33 (JPEG using in-camera defaults)
with Sony SAL1855 SAM
 
Sony Alpha SLT-A33 (RAW Image Data Converter)
with Sony SAL1855 SAM
f8, 100 ISO
f8, 100 ISO
     
f8, 100 ISO
f8, 100 ISO
     
f8, 100 ISO
f8, 100 ISO
     
f8, 100 ISO
f8, 100 ISO

Sony Alpha SLT-A33 results : Real-life resolution / High ISO Noise / Handheld Twilight (HHT) / Multi-frame NR / HDR



All words, images, videos and layout, copyright 2005-2014 Gordon Laing. May not be used without permission.

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