The downside is that SLR lenses tend to run bigger than native options, and these are even longer than the DSLR versions. That's because lenses need to be set a certain distance from the image sensor to work. Mirrorless cameras put less distance between the mount and sensor, so the lens has to be longer to compensate.

Sigma 28-70mm f/2.8 DG DN Contemporary Lens for Leica L

As for shallow depth of field and bokeh, I’ve always been a fan of what comes out of all the Sigma lenses that I’ve reviewed, and the 28-70mm is clearly no exception. This isn’t an f1.4 lens but at f2.8, you can get images with pretty decent bokeh. The depth of field can be nice and shallow, especially since this lens is able to focus pretty closely. Thanks to the rounded nine-blade diaphragm, the bokeh quality is also very smooth and inviting. The lens comes with an AF/MF switch ②, which has a firm but ergonomic action, and the focus and zoom rings ① are smooth and precise owing to SIGMA’s advanced lubricant technologies. So we have an advanced design, a nice close-focus range and the lens weighs in at 470 grams. While this is light-weight and easy to handle, I was particularly impressed with the rendering characteristics. This is something I typically don’t expect to be very good on zoom lenses at this price point. I am, however quite impressed with what Sigma has developed here. We do realise, however, that bokeh evaluation is subjective, so we've included several 100% crops for your perusal. Sharpness

True to the Contemporary line’s core concept, the 28-70mm F2.8 DG DN was developed to offer the right balance of performance and portability. It has been designed to deliver outstanding image quality that rivals SIGMA’s Art line lenses in a body light enough for day-to-day use.

SIGMA Interchangeable Lenses for L-Mount | SIGMA L MOUNT SIGMA Interchangeable Lenses for L-Mount | SIGMA L MOUNT

There's both good news and bad news on the bokeh front. The Sigma 28-70mm F2.8 DG DN's bokeh has a really pleasing, smooth look to it, with only minimal onion ring effect and smoothly-rounded, step-free edges even when stopped down to F4. Here’s a 100% crop of the photo above. Notice how you can read even the smallest words in this photo even though they are technically not even the focus points. Keep in mind that this was taken using 640 ISO as well, not 100 ISO. Stopping down to F5.6, we see a slight improvement in sharpness at wide-angle and a bigger improvement at telephoto, since the lens is softer wide open at 70mm than it is at 28mm. You'll appreciate this improvement in sharpness more if you're shooting with a high-resolution camera. We tested with both the 42-megapixel Sony A7R III and 47-megapixel Panasonic S1R; with a 24-megapixel body, that difference would be much less noticeable. Here’s a photo of the Woolworth building taken with the S1 and the 28-70mm f2.8 DG DN Contemporary lens. The focal length used here was 70mm with the settings being f6.3 and 100 ISO. Taking a close look in the middle again reveals nice fine details even coupled with the high res A1 body, and closing the aperture isn’t necessary to boost the detail.Another thing you can see is how sharpness is best at the center of the lens and it shows that there is a slight fall off as we move to the edges of the frame. One thing is clear though: as much as the optical formula appears to be the same on both lenses, they certainly have some notable differences that make it difficult to label the Leica just a “rehoused” Sigma. While optically identical, there are other factors to consider. Sigma Strengths In terms of image quality, the 28-70mm f2.8 also delivers the goods. In fact, Sigma says that this zoom offers the same optical performance as the 24-70mm F2.8 DG DN Art lens, which as we know, is designed to be their best, and for pro use. That’s pretty impressive considering how much smaller this lens is as well. Lens construction: 16 elements in12 groups, with 2 FLD elements, 2 SLD elements and 3 aspherical elements I generally shoot the way I normally shoot with all the gear I review. From what I was able to get from the fp L, I didn’t have any issues. I don’t do much sports though but for everything else I’ve shot, the camera worked great. It’s an electronic shutter, so I did have some issue with fluorescent lighting but that’s with any electronic shutter.

L-Mount - Panasonic L-Mount - Panasonic

As far as image quality, colors, and sharpness are concerned, both lenses perform incredibly well with nearly identical images coming out of each lens. Where they differ, however, is most noticeable while actually shooting. While the autofocus on the SL-2 is nowhere near as fast as the new generation of mirrorless systems From Nikon, Sony, or Canon, there is a significant performance difference between each of these lenses on a Leica camera. I should point out that the technology Sigma uses in its lenses is not the same as the linear, electromagnetic system that Sony uses in their newer lenses. If you’re shooting sports or any other fast-moving subject, I don’t think Sigma’s design will outperform modern Sony lenses. This lens is not designed for that type of application, but I do think that is something most people will know going into it.Importantly, the lens is also fully compatible with the "Direct Manual Focus (DMF)" system feature of Sony cameras that enables the user to instantly switch between autofocus and manual focus. That said, the 28-70mm F2.8 Contemporary still offers solid image quality. This is especially true if you're willing to stop down a bit, don't shoot with an extremely high-res body or don't need perfection in the corners. Let's take a closer look. As you might expect, the featherweight Sigma 28-70mm F2.8's body is predominantly constructed from polycarbonate, although it does still have a metal mount and build quality is good. And while it isn't fully weather-sealed like its nearest rivals, the mount still includes a seal that should help protect your camera body from the elements, if not the lens itself. For the added cost and heft, the Sigma 24-70mm Art offers even better image quality and includes an 11-bladed aperture. It also provides a little extra wide-angle coverage and full weather sealing. If you can stretch your budget a little further, we find it's a worthwhile choice.

Sigma 28-70mm f2.8 DG DN Contemporary Lens Review Sigma 28-70mm f2.8 DG DN Contemporary Lens Review

Neither lens includes built-in Vibration Reduction, instead relying on the camera body to supply this feature. Now for focusing on the Sony A1 using a central area and single AFS mode at 70mm f2.8 and you can see there’s a minor contrast-based wobble at each focus-pull to confirm, but the process is still fairly swift and quiet too. Switching the A1 to Continuous AF mode though forces the body to use phase-detect AF alone which here is refocusing noticeably faster than before, and in my tests didn’t reduce accuracy. So it can be worth experimenting to find the best mode. One of the lens’s biggest features is the stabilization, which, when used with Dual IS 2.0 on the Panasonic S1 and S1R, is good for up to a staggering 7 stops of stabilization. Combined with the bright f/2.8 constant aperture, the S Pro 70-200mm should be a low light beast.

The only real issue that I even really encountered is there were times when I wish I had just a bit more width in terms of focal length. There were moments when I wish I had the extra 4mm from the Sigma 24-70mm f2.8 DG DN Art lens I was reviewing at the time as well. 4mm does not sound like a lot but when we’re talking about the wider end of the spectrum, it can make a larger difference. I feel like the 24-70mm gives me just that extra bit of versatility and flexibility. With that said, I’ve never been a fan of the 28mm focal length, so I’m sure that comes into play here as well. If you prioritize outright image quality and durability over size, weight and cost, we'd recommend the fully weather-sealed Sigma 24-70mm F2.8 DG DN Art. And for E-mount shooters who are more size, weight and cost-conscious but who need to shoot regardless of the elements, the Tamron 28–75mm F/2.8 Di III RXD also offers a compelling alternative if you can live with its more distracting bokeh. I prefer distinct focal length differences. A 24mm is perspectively easily discernable from a 40mm and a 40mm easily discernable from an 85mm. With the lens set to its maximum aperture of f/2.8, there is some obvious light fall-off in the corners at both ends of the zoom range. Stopping-down to f/5.6 virtually eliminates this.