Sigma 210101 18-35mm F1.8 DC HSM Lens for Canon - Black

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One real problem we had in real-world shooting with the 18-35mm was with autofocus. Depth of field is limited at F1.8 - especially at 35mm - which means that even slight misfocusing can become very visible if you look closely at your images. We shot with a range of Canon SLRs, from the entry-level EOS 100D to the top-of-the-line EOS 7D, and all had problems focusing absolutely correctly all the time. This was usually only obvious when shooting at apertures larger than F2.8. In general, we got slightly better results by using the central AF point (with recomposition) compared to using off-centre AF points, but this didn't eliminate focus errors entirely. At 18mm full-aperture sharpness is excellent from corner to corner, though sharpness in the outer field drops slightly through the zoom range to 35mm. For most focal lengths and apertures, though the sharpness differs by 5% or less across the frame.

Sigma 210101 18-35mm F1.8 DC HSM Lens for Canon - Black

For wildlife photographers who need additional reach, or photographers who only publish images online, 18 megapixels may be enough. But for me, 18 megapixels is a big drop in resolution, so I would not use the Sigma 18-35mm f/1.8 for my own still photography.Despite its limitations when shooting stills, the Sigma 18-35mm f/1.8 is surprisingly great for video on the R5. Here’s why. Large f/1.8 aperture The Sigma 18-35mm f/1.8 is bulky, long, and weighs nearly two pounds (1 pound, 15 oz to be exact). This makes the lens somewhat cumbersome and heavy when shooting handheld on the R5. Requires an adapter The 18-35mm is remarkably sharp even wide open at F1.8, and in the wider half of its range (18-24mm), there's no measurable increase on stopping down (i.e. the lens is effectively diffraction limited). At the longer end (28-35mm) there's a slight improvement in sharpness on stopping down to F4, but in practice it's unlikely to be especially noticeable. For an F1.8 zoom, this is little short of astonishing.

Fstoppers Reviews the Sigma 18-35mm f/1.8 DC HSM Art Lens Fstoppers Reviews the Sigma 18-35mm f/1.8 DC HSM Art Lens

By the way, you may enable Movie Cropping and shoot “4K Crop” video with any lens, not just APS-C. I’m simply pointing out that — unlike still photos — 4K video on the R5 is higher quality than you may expect. No overheating in 4K CropI just received my new Sigma 18-35 1.8 A and i noticed that the focus sound on live view on my T4i is not quite as the non-live view focus, do you have the same thing with your lens or my lens has a problem? As good as the Sigma 18-35mm f/1.8 may be for video on the R5, it does come with a few downsides to be aware of. Size and weight

Sigma 18-35mm f/1.8 ART review: best Canon R5 video lens? Sigma 18-35mm f/1.8 ART review: best Canon R5 video lens?

Getting the best possible focus is the responsibility of the camera. Some lenses (usually through decentering or spherical aberration) make it impossible for the camera to achieve optimal focus. But a good copy, and in particular after micro-AF-adjustments that can deliver spot on AF, should do so every time (within small tolerances, of course). A consequence of all of this is that in principle you'll get the very best results at large apertures by focusing and shooting in live view. This has its own pitfalls though - for example when focusing manually with Nikon's DX SLRs you have to remember to set the aperture to F1.8 before entering live view, as they're incapable of adjusting the lens's diaphragm during viewing. If you initiate live view at a smaller aperture, then you risk getting misfocused images. Meanwhile Canon users may have to set the aperture to F1.8 and press the depth of field preview button to force the lens wide open for accurate manual focusing, when shooting in bright light. Autofocus microadjustment Our final comparison, ironically, has the new Sigma up against the firm’s new 35mm f/1.4 DG HSM A, the best performing full-frame 35mm lens in our database. Although it’s easier to make a high-speed 35mm than either a 24mm f/1.4 or a 18mm f/3.5, the Sigma 35mm is without doubt a superb performer optically and yet the new Sigma 18-35mm zoom comfortably achieves a higher DxOMark Score. The new zoom also has slightly higher levels of sharpness and has the edge in uniformity. Less important perhaps is the superior transmission score, while the differences between distortion, vignetting and chromatic aberration are practically negligible.

I’m primarily a Canon full-frame shooter, so this lens from 2013 has never been on my radar. But that changed once I started shooting video with the Canon EOS R5.

Sigma 18-35mm F1.8 DC HSM Review - Digital Photography Review

The HSM (Hyper Sonic Motor) ensures a silent, high-speed AF function. Optimizing AF algorithm, smoother AF is achieved. It also enables full-time manual focusing capability which allows sensible focus adjustment by simply rotating the focus ring. Because an f1.8 APCS lens on an APSC sensor DOES gather the same total amount light as a f2.8 FF lens on a full frame. The APSC lens focuses all that light on a smaller circle, the FF lens focuses it on a larger one. But they both gather about the same number of photons in the same time. I certainly wouldn’t recommend buying this lens if you only have a full frame body, obviously, but if you happened to also have a full frame body and didn’t have a 35mm prime this might prove a useful bonus. Unlike a prime lens with a single focal length, the Sigma is variable. You may zoom in-and-out without physically moving your camera setup. This offers greater flexibility, speed and creative control when composing a shot — especially when mounted on a tripod. And that’s the confusing thing about “4K Crop” video on the R5, for when an APS-C lens like the Sigma is attached, it may appear the R5 is shooting in regular 4K because 4K HQ mode is disabled. But it’s not. Behind the scenes, with Movie Cropping enabled, the R5 is oversampling 5.1K when shooting 4K.All in all this lens is at the top of the heap for optical performance in a crop sensor lens. AF Concerns The 18-35mm doesn't show too much in the way of chromatic aberration, but it's visible if you go looking for it. Under different conditions it can show the two main types of CA, lateral and longitudinal.