The minimum focusing distance is 20cm (just under 8 inches). The lens offers 0.33x magnification (1:3), making it a fairly decent macro lens. The lens uses an internal focusing design, meaning the front element doesn't rotate. The lens took about a second to go from infinity to close-focusing distance. Sigma uses an electrical motor for this lens, making it fairly fast and quiet, but Sigma's more recent HSM focusing motors are a bit quieter. Wide-angle distortion isn't extreme at 18mm, and there's very little pincushion distortion to speak of above 26mm, either. Happily, distortion isn't extreme, and there is a point of parity around 26mm where the distortion effect is negligible. It's about what you would expect with a zoom lens of this range barrel distortion on the wider end, and some pincushion distortion when zoomed in. At any other setting, the corners are below a quarter-stop darker, or practically insignificant. At 18mm, this produces corners which are a half-stop darker than the center at any other focal length, it hovers at around a third-stop darker. Light falloff also isn't much of a factor for this lens just a small amount when the lens is used wide open at ƒ/2.8. The aperture choice doesn't appear to have any impact on results for chromatic aberration. In fact, performance is actually fairly good across the board at ƒ/11-ƒ/22, making it an excellent macro lens.ĬA is nicely controlled by this lens, showing slightly at the wide angle, but reducing to very low levels as the lens is stopped down. At ƒ/8, we actually note slightly better results for sharpness than at results we found in the 24-35mm area.ĭiffraction limiting sets in around ƒ/11, but this actually serves to even out the lens' performance, making the corners about as sharp as the center. Wide open performance (ƒ/2.8) at 50mm is average stopping down is definitely required to obtain better results for sharpness. It's not a dealbreaker in this case, but it is noteworthy. We'll chalk it down to our sample, and other copies of the lens may not show these results, but it does reinforce the message to try to buy with a good return policy or be able to test thoroughly the copy you're aiming to buy. Zooming in provides similar results through the midrange (24-35mm), with a small aberration at 35mm and ƒ/4 which shows some exaggerated corner softness on the left side. As the lens is stopped down this corner softness slowly reduces, but never entirely disappears it's a toss-up between ƒ/5.6 and ƒ/8 for the optimal setting at this focal length, trading central and corner sharpness in small degrees. Mounted on the Canon 7D, at 18mm and ƒ/2.8, the lens produces a small sweet spot of sharpness in the center of the frame, offering excellent sharpness there, and falling off to some light corner softness. The 18-50mm ƒ/2.8 DC Macro offers good results for sharpness, better at the wide angle than zoomed in to 50mm. The lens ships with a petal-shaped hood, accepts 72mm filters, and sits at around the $400 price point. Sony E Mount, Sony A Mount, legacy Minolta A mount, our spiritual cousins in the RX series. This is a Reddit's best source for talking about the Sony Alpha photography system. Proud to be the #1 Camera-Brand Subreddit!
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