Sony SAL-1118 DT 11-18mm f4.5-5.6 lens review
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Written by Gordon Laing
Quality
Sony DT 11-18mm vs DT 18-70mm resolution comparison, with Alpha A100
 | To measure and compare the Sony DT 11-18mm’s resolving power we photographed the Enhanced Digital Camera Resolution Chart with it and the DT 18-70mm kit lens using the Sony A100 body set to its best quality JPEG and settings. Anti-shake was turned off.The crops are taken from the original images, saved as High Quality JPEGs in Photoshop CS2 and presented here at 100%. Each number represents 100 lines per picture height (lpph), so a figure of 20 means a resolution of 2000 lpph. |
| We tested the Sony DT 11-18mm at a focal length of 18mm where it delivered 2100 and 2150 lpph of horizontal and vertical resolution respectively. While the horizontal figure was fractionally below the kit zoom, it doesn’t translate into perceptively greater real-life detail – see our outdoor results for examples. The greater apparent sharpness of the kit zoom in the test below is also due to it being shot with the A100’s Vivid colour setting, compared to the Standard setting used for the DT 11-18mm; if you apply additional sharpening and contrast to the DT 11-18mm results you can get a similar looking effect. Next up, the Sony DT 11-18mm corner sharpness. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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2100 lpph, DT 11-18mm at 18mm, f8, 100 ISO | 2150 lpph, DT 18-70mm at 35mm, f8, 100 ISO |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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2150 lpph, DT 11-18mm at 18mm, f8, 100 ISO | 2150 lpph, DT 18-70mm at 35mm, f8, 100 ISO |
Sony DT 11-18mm vs DT 18-70mm corner sharpness
| To compare the corner sharpness of the Sony DT 11-18mm against the DT 18-70mm, we photographed the Enhanced Digital Camera Resolution Chart with each lens at their shortest and longest focal lengths and various apertures in Aperture Priority mode using a Sony A100 body.The A100 was set to its best quality JPEG and default image tone and sharpening settings, and anti-shake was turned off. The crops are taken from the extreme lower left corner of the chart and presented here at 100%. |
| Despite the differences in focal range, both lenses actually exhibit similar optical artefacts in the corners when zoomed all the way in or out. At its widest focal length, the DT 11-18mm exhibits noticeable softening in the corners at larger apertures and only gets this under control when stopped down quite significantly. Zoomed-into 18mm though, the DT 11-18mm delivers a far superior result, with only slight softening in the corners at the maximum aperture and a good result as you stop it down. While it’s interesting to compare the similarities between each lens zoomed-out and zoomed-in, the really important comparison is when both lenses are set to 18mm. In this instance the DT 11-18mm delivers a far superior result, so once again if you own both lenses and are shooting at 18mm, use the ultra wide lens in favour of the kit zoom. Our next results page tests the Sony DT 11-18mm fringing and macro performance. |
Corner sharpness, shortest focal length
Sony DT 11-18mm at 11mm using Sony Alpha A100 | ||||||
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11-18mm at 11mm f4.5 | 11-18mm at 11mm f5.6 | 11-18mm at 11mm f8 | 11-18mm at 11mm f16 | |||
Sony DT 18-70mm at 18mm using Sony Alpha A100 | ||||||
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18-70mm at 18mm f3.5 | 18-70mm at 18mm f5.6 | 18-70mm at 18mm f8 | 18-70mm at 18mm f16 | |||
Corner sharpness, longest focal length
Sony DT 11-18mm at 18mm using Sony Alpha A100 | ||||||
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11-18mm at 18mm f5.6 | 11-18mm at 18mm f8 | 11-18mm at 18mm f11 | 11-18mm at 18mm f16 | |||
Sony DT 18-70mm at 70mm using Sony Alpha A100 | ||||||
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18-70mm at 70mm f5.6 | 18-70mm at 70mm f8 | 18-70mm at 70mm f11 | 18-70mm at 70mm f16 | |||
Sony DT 11-18mm vs DT 18-70mm purple fringing comparison
 | To compare the purple fringing of the Sony DT 11-18mm against the DT 18-70mm, we photographed a test chart with areas of very high contrast using each lens at their shortest and longest focal lengths and with their apertures wide open. The crops are taken from the upper left corner of the chart and presented here at 100%.Both lenses exhibit purple fringing at their shortest focal lengths, although the DT 11-18mm shows a much better result when zoomed-in – also compare this to the DT 18-70mm at 18mm. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |||||
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11-18mm at 11mm f4.5 | 11-18mm at 18mm f5.6 | 18-70mm at 18mm f3.5 | 18-70mm at 70mm f5.6 | |||
Sony DT 11-18mm vs DT 18-70mm macro comparison
| To compare the macro capabilities of the Sony DT 11-18mm against the DT 18-70mm, we photographed a custom chart at a focal length and distance which delivered the maximum possible reproduction. The dark lines are 10mm apart and the result is not cropped. Smaller areas are preferred in this test. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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11-18mm at 18mm f8 Max area of 168x112mm | 18-70mm at 70mm f8 Max area of 82x54mm |
| The DT 11-18mm can certainly focus quite close to its subjects, but even zoomed-into 18mm, you’re not going to get a massive reproduction. The best result we managed was an area of 168x112mm. If you want better close-up reproduction on your Alpha, get a dedicated macro lens. Next up are our Sony DT 11-18mm distortion results. |
Sony DT 11-18mm vs DT 18-70mm geometry, shortest focal length
| To compare the geometric distortion of the Sony DT 11-18mm against the DT 18-70mm at their shortest focal lengths, we photographed a test chart consisting of a grid pattern at an aperture of f8. The images were then analysed with Imatest using 5th Order line calculation and the full areas presented here at a reduced resolution. Smaller percentages are better.Zoomed-out to 11mm, the Sony DT 11-18mm exhibits 3.87% barrel distortion which is actually pretty similar to the kit lens when it’s zoomed-out. The important difference here though is the DT 11-18mm is capturing a much greater area. This is however a similar result to the Canon EF-S 10-22mm when its zoomed-out. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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11-18mm at 11mm f8 Distortion: 3.87% barrel | 18-70mm at 18mm f8 Distortion: 3.6% barrel |
Sony DT 11-18mm vs DT 18-70mm geometry, longest focal length
| To compare the geometric distortion of the Sony DT 11-18mm against the DT 18-70mm at their longest focal lengths, we photographed a test chart consisting of a grid pattern at an aperture of f8. The images were then analysed with Imatest using 5th Order line calculation and the full areas presented here at a reduced resolution. Smaller percentages are better. Zoomed-into its longest focal length, the Sony DT 11-18mm exhibits 0.94% barrel distortion, which is more noticeable than the 0.27% pincushion distortion of the kit lens when it’s zoomed-in. Of course the fairer comparison is with both lenses at 18mm, where the DT 11-18mm and DT 18-70mm exhibit 0.94% and 3.6% of barrel distortion respectively. So if you own both lenses and are shooting at 18mm, the DT 11-18mm will deliver less geometric distortion. Our final results page tests the Sony DT 11-18mm light fall-off. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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11-18mm at 18mm f8 Distortion: 0.94% barrel | 18-70mm at 70mm f8 Distortion: 0.27% pincushion |
Sony DT 11-18mm vs DT 18-70mm uniformity, shortest focal length
| To compare the vignetting and light fall-off of the Sony DT 11-18mm against the DT 18-70mm at their shortest focal lengths, we photographed a white target with a highly diffused filter; each lens was focused to infinity with its aperture wide open. The images were then analysed with Imatest and the full areas presented here at a reduced resolution. Bigger percentages are better.Light falls off to 65.4% of the maximum when it reaches the corners of the Sony DT 11-18mm when it’s zoomed-out to 11mm. This is roughly the same as the DT 18-70mm kit lens when its zoomed-out to 18mm, although the gradient is smoother on the ultra-wide lens and less noticeable in real-life. It’s also a much better result than the Canon EF-S 10-22mm when it’s zoomed-out, although the Sony lens isn’t as optically fast. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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11-18mm at 11mm f4.5 Mean corner fall-off: 65.4% | 18-70mm at 18mm f3.5 Mean corner fall-off: 63.3% |
Sony DT 11-18mm vs DT 18-70mm uniformity, longest focal length
| To compare the vignetting and light fall-off of the Sony DT 11-18mm against the DT 18-70mm at their longest focal lengths, we photographed a white target with a highly diffused filter; each lens was focused to infinity with its aperture wide open. The images were then analysed with Imatest and the full areas presented here at a reduced resolution. Bigger percentages are better. With the DT 11-18mm zoomed-into its longest focal length, the light falls-off to 62.2% of the maximum in the corners. This is actually pretty much identical to the kit lens at the same focal length, although again the gradient is subtle and it’s a better result than Canon’s ultra wide angle for EF-S bodies. Now for some real-life results, let’s head on over to our Sony DT 11-18mm sample images. |
Sony DT 11-18mm Using Sony Alpha A100 | Sony DT 18-70mm Using Sony Alpha A100 | |
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11-18mm at 18mm f5.6 Mean corner fall-off: 62.2% | 18-70mm at 70mm f5.6 Mean corner fall-off: 87.7% |
