Sigma's 50-100mm f/1.8 Art is the world's fastest medium telephoto, zoom lens.
If you shoot on a DSLR or mirrorless camera, third-party lens brands are often regarded as less appealing than native brand models from the likes of Canon, Sony, Nikon or Panasonic. However, this has changed over the past few years especially after Sigma introduced their ART line of premium glass. The ART Series offers a robust build quality and top-notch optics at reasonable prices putting them in close competition with native brand options that are sold at double the price.
Sigma's 18-35mm f/1.8 ART has quickly become a staple for video shooting on a DSLR, mirrorless or cinema camera that utilizes a cropped APS-C sensor and is one of the most popular aftermarket lenses currently available. When it launched, it was a first of its kind holding the reins as the only f/1.8 zoom lens ever produced. Fast-forward just a few years later and Sigma has released a sibling, the 50-100mm f/1.8 which is priced slightly higher at $1,099.
Design & Build Quality
Just like the rest of the ART line, the 50-100mm feels great in the hand with premium build materials and a very robust design. The downside of this is this model is very bulky, so portability and ease of use for run and gun are hindered. Due to its size, the 50-100mm comes with a tripod collar for mounting use with small DSLRs or mirrorless camera though this is both easy to adjust and remove.
If you are going to be using it on a larger bodied cinema camera like the FS5 or FS7, you will want to rig it up with a lens support you'd be taking a risk using it on the non-native mount with an adapter like the Metabones or Commlite. I have found that SmallRig's 1087 Long Lens Support is an affordable solution for this as long as you have a way to rig it up with 15mm rails.
The focus and zoom rings are well contoured and in the traditional locations (looking at you, Tamron). Both rings move smoothly without the obnoxious focus-by-wire functionality found in many of the native mirrorless options, pulling focus is easy and convenient.
Just like the 18-35mm ART, the barrel extension is all done internally when zooming so the length of the lens doesn't change throughout the range. I am a fan of the look of the ART line with its sleek black finish and small silver ART badges. It offers classy yet simplistic appeal that matches its high craftsmanship.
Since Sigma's 50-100mm f/1.8 ART is for APS-C sensors only, the 35mm equivalent range is more like 80-160mm. While it will fit on a full-frame body, the lens will display a heavy barrel vignetting when shooting at the wider end of the range. Being able to shoot at this zoom range at f/1.8 is a dream for low-light situations and allows for plenty of room to achieve a beautiful depth of field (even overkill in some cases). Unlike some of the more expensive lens options, the highest maximum aperture stop is only f/16 though plenty for most needs as lens diffraction will often play a factor in degrading image quality past this stop.
Internally, are nine rounded diaphragm blades with 21 optical elements separated in 15 groups. Those interested in using a filter can take advantage of the metal 82mm filter thread found on the front of the lens. The included tripod collar is compact yet functional and helps to take the bulky weight's tension off the lens mount. While it would be helpful at this range, there is no internal optical image stabilization so ideal performance will be with a tripod/monopod or a mirrorless body with 5-axis image stabilization.
While this is a f/1.8 lens, some inconsistency occurs with my Metabones Mark IV T adapter which causes the aperture reading on my a7RII's rear display and EXIF data to display as f/1.7 wide open instead of f/1.8 though this has no effect on performance.
Performance & Function
The ergonomics of the 50-100mm are significantly weaker than the 18-35mm due to the large increase in size and weight. While the 18-35mm has no problem when it comes to the traditional run and gun environment, the 50-100mm is a bit more daunting for this task, and you will want to pre-plan a comfortable rig if you plan on shooting for extended periods of time handheld or over the shoulder.
As stated earlier, I always utilize the tripod collar when shooting on my a7RII and when I am rigging up my FS7 for use with this lens, I find a lens support is a must as it just isn't worth the risk of damage to the lens mount while working in the field.
I took some test shots using my a7RII to see how the optical performance is affected by changes in aperture and focal distance.
Disclaimer: the following images have resized and compressed for web friendly viewing, you can download the full resolution, straight out of camera images via Flickr.
Since this lens falls into the focal range of a medium telephoto, you won't experience much barrel distortion besides some slight warping near the 50mm end.
Lens vignetting is a pretty common trait for lenses of all price-points, especially when shooting wide open. When shooting on an APS-C sensor, the 50-100mm f/1.8 ART does experience some noticeable vignetting at f/1.8 though it improves as you stop down with f/4 being the sweet spot where the vignetting disappears for the remainder of the aperture range.
Keep in mind, vignetting can be easily removed in post for photography with a few clicks in a software like Lightroom yet for video this can be a bit more cumbersome to deal with.
I tested the sharpness at three different focal ranges and am impressed with the results. Both the center and corner sharpness are shown to be excellent at all focal lengths. The wide-open performance suffers slightly when compared to a few stops down. Operating at f/1.8 should never really be an issue even if you are looking to preserve optimal image clarity.
You will typically see chromatic aberration in high-contrast areas on even the most expensive lenses, but the 50-100mm f/1.8 ART performed well in this area with a minimal amount of CA visible in my test shots. In these instances, an untrained eye would never notice it and even I could only locate it when viewing my shots at a 1:1 ratio.
This means the lens is highly usable in most situations without correcting CA although this is often a one-click fix when editing images in any of the modern photo editing suites.
Sigma's second generation f/1.8 zoom lens is just as impressive as the first. With top-notch optics and a high build quality, there are not many negative aspects you can find about the 50-100mm f/1.8 ART besides the increased size and weight. Having said this, I still think the form factor is an impressive feat considering all the advanced engineering that goes into designing a zoom lens with these capabilities.
While I think the 18-35mm f/1.8 ART is more of the “must-have” lens for most photographers or videographers shooting on an APS-C camera, the 50-100mm is a top contender giving you a longer focal range to utilize without sacrificing depth of field or low-light performance. As long as you are well aware of its bulkiness and lack of image stabilization, I think the 50-100m f/1.8 remains a smart buy, especially at a sub-$1,100 price-point.