Except the EF 50mm F/1.4 USM lens. It has an additional clutch system to allow MF override just like ring type USM lenses have. Some USM lenses use an electronic focus ring like STM lenses. All RF lenses whether STM or USM use an electronic focus ring.-Demetrius Canon EF 16-35 mm f/2.8L III USM - test obiektywu. 1. Wstęp. Firma Canon ma duże doświadczenie w produkcji pełnoklatkowych, ultraszerokokątnych zoomów o świetle f/2.8. Niniejsza tabela prezentuje modele, które mieliśmy okazję obejrzeć na rynku w ciągu ostatnich 20 lat. The RF 15-35mm f/2.8L IS USM’s broad zoom ring has a step-up in size roughly at its mid-point, which makes it easy to identify and differentiate from the manual focus ring that is further forward. Both have a smooth, easy action. At the far end, close to the front element, the Canon RF 15-35mm f/2.8L IS USM has a dedicated control ring. Canon EF 16-35mm F2.8L III USM Canon EF 16-35mm F2.8L USM Canon EF 16-35mm F4L IS USM Canon EF 17-40mm f/4.0L USM Canon EF 180mm f/3.5L Macro USM Canon EF 200-400mm f/4L IS USM Extender 1.4x Canon EF 200mm f/2.8L II USM Canon EF 200mm f/2L IS USM The Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens is sharp to the corners even with a wide open aperture. Corner performance is slightly weaker from 50-70mm with a wide open aperture, but still not bad. The EF-S 15-85 shows slight improvement in sharpness when stopped down to f/8, but really, little improvement is needed. The falloff of the 16-35mm f/2.8 L improves at f/4, and remains the same at smaller apertures. It has has strong falloff at 16mm at f/2.8. The gray shots are of my Expodisc. This is a deviously tough test which shows even the slightest falloff. Except at 16mm at f/2.8, you'll almost never see this in normal photography. Canon. RF 15-35mm F2.8L IS USM. Canon's fastest ultra-wide-angle zoom and part of a trinity of essential pro lenses, boasting a Nano USM motor, 5-stops of image stabilisation plus 3 Aspherical and 2 UD elements for stunning sharpness. Be rewarded when you buy RF lenses with Lens Reward, claim up to £300 cashback on each of your next 5 lens 1yFUb0.