The Sigma 300-600mm F4 DG OS Sports ($5,999.99) is an absolutely massive lens. Its optical formula, which delivers the previously unrealized combination of a super telephoto focal range, a bright F4 aperture, and zoom, accounts for its heft. Dedicated hobbyists and pro photographers who specialize in sports and wildlife imaging will find reason to build up their arm muscles, as the images it captures are truly phenomenal, at a price less than half of the Sony FE 600mm F4 GM OSS ($12,999.99). It's an incredible optic that will reward you with fabulous photos, but its bulky design makes it a challenge to use in practice.

Design: Keep Your Chiropractor on Speed Dial

After two weeks of lugging the Sigma 300-600mm F4 around for wildlife snaps at a refuge, the zoo, and my backyard, I walked away with some fantastic photos and a seriously sore shoulder. At 18.5 by 6.6 inches (HD) without the hood attached, and 8.8 pounds, the lens is a behemoth. That's big even among its peers. The Sony FE 600mm F4 GM OSS is a little shorter (17.7 by 6.4 inches), but appreciably easier to handhold at 6.7 pounds.

(Credit: Jim Fisher)

However, the FE 600mm F4 doesn't have a zoom option. With the Sigma 300-600mm F4, you get the narrow angle you'll want for distant subjects like birds and the versatility to zoom in and out to get different angles when capturing field sports. Adding zoom while still maintaining the same F4 optics as the FE 600mm is no doubt a major factor, as the Sigma zoom uses a significant amount of glass in its 28-element/21-group optical formula.

Most other zoom lenses that reach the 600mm focal length don't weigh as much, but they don't gather as much light either. The Sigma 150-600mm F5-6.3 DG DN OS Sports, 60-600mm F4.5-6.3 DG DN OS Sports, and Sony FE 200-600mm F5.6-6.3 G OSS are pounds lighter and cost thousands less, but all capture less than half the light at the 600mm focal length versus the Sigma 300-600mm F4.

(Credit: Jim Fisher)

Still, at close to 9 pounds and 23 inches long with the hood attached, the 300-600mm stretched me to my physical limits for handheld photography. I paired it with a BlackRapid sling strap and wasn't bothered by the weight hanging off my shoulder, but bringing the lens and camera up to eye level to hone in on a subject took some effort. Every day is an arm day with this lens.

You may prefer to pair the 300-600mm F4 with a monopod or tripod. I won't fault you, and if I were using it for football or soccer instead of wildlife, I'd likely grab a monopod as a support. I like using the monopod with a big lens for sports because the action is typically at eye level, and I can more easily pivot the camera around to follow action without having to support its weight myself. But for birds and animals in the wild, I'm often pointing my camera up toward the sky or a branch, or down toward the water or ground, and find a monopod too restrictive.

(Credit: Jim Fisher)

It's easy enough to attach a support. The lens includes a large tripod foot with forward and rear 1/4-inch-20 threads and a larger central 3/8-inch-16 post. The former is the size most quick-release plates use, while the latter is found on some heavy-duty tripods and straps. The foot also has dovetail cuts on its side, so it mounts directly into Arca-Swiss heads without the need for an additional quick-release plate.

The foot is permanently attached to a collar for 360-degree rotation and is switchable between continuous rotation and 90-degree detent clicks, with a thumbscrew to lock it in place. The collar also includes a pair of strap lugs, and the foot itself works as a carry point. There's plenty of space between it and the lens barrel, so there's no danger of scraping your knuckles, and the foot has a soft leatherette cover, so it provides a little bit of cushion for your fingers. The foot also has a Kensington lock slot, so you can lock it down for some extra peace of mind when covering events.

(Credit: Jim Fisher)

The lens may weigh close to 9 pounds, but it's not due to dense materials. The lens houses its optics in a barrel made from light, tough magnesium alloy, and its hood is carbon fiber. Both the lens and hood are finished in white, which is a common choice for extra-big lenses. The color choice is practical—Sigma uses white thermal insulation paint so the lens reflects more sunlight than it absorbs, and doesn't get as hot when used for prolonged periods on a sunny day. The downside is that the thermal paint shows scuffs readily; my review sample of the lens arrived with some noticeable black marks on the barrel and hood, and I'm pretty sure I added a few along the way.

(Credit: Jim Fisher)

The 300-600mm includes dust and splash protection, as well as oil- and moisture-repelling fluorine on its front element. The front glass is too large to support a filter, so the 300-600mm works with 40.5mm rear drop-in filters instead. It includes a clear glass filter, and it's easy enough to swap it out for any other 40.5mm filter. The basic holder doesn't support adjustable filters, however, so you'll need to pick up the $193 Sigma CPL filter to set polarization or its $265 VND Filter if you want variable neutral density control.

In addition to the hood, the lens includes a slip-on lens cover to protect the glass during transport and storage, a shoulder strap, and a large soft case that doubles as a backpack.

(Credit: Jim Fisher)

Sigma makes two versions of the 300-600mm, one for L-Mount Alliance cameras and another in E-mount for Sony cameras. The two lenses are identical, but there are some functional differences between the camera systems. The L-mount version is compatible with rear 1.4x and 2.0x teleconverters, works with Sigma's UD-11 USB configuration dock, and supports full-speed focus drive with any compatible camera. The E-mount version does not work with teleconverters and is limited to 15fps focus, restrictions that Sony puts on all third-party lenses, not just this one.

Controls: Flexible Control Ring for Preset and Power Focus

Super telephoto lenses typically have more control buttons, rings, and toggles than shorter options. The extra features are welcome when using a long lens, which can be more challenging from both a physical (in the case of this heavyweight zoom) and technical level.

(Credit: Jim Fisher)

The 300-600mm puts control panels on both sides of its barrel. The left has toggles to set the focus mode (AF/MF), autofocus limit (Full, 10 meters to infinity, 2.8 meters to 10 meters), stabilization mode, and the Custom mode (C1, C2, Off). The Custom switch is included in both E and L copies of the lens, but only works with L-mount, as the UD-11 dock is required to configure the lens. The dock lets you configure a custom focus limit, tune autofocus response to balance speed and accuracy, and update firmware using Sigma's desktop software.

There are a few more controls on the right side of the barrel. There's a toggle to set the forward control ring function (Off, Power Focus, Preset), a Set button to record a focus position for the Preset function, and a Beep On/Off switch that will silence the lens or provide an audible cue to let you know you've changed the Preset focus distance.

(Credit: Jim Fisher)

The Preset function isn't on every lens, but it's handy to have. It lets you record a focus point in memory and go back to it in an instant with a simple twist of the 300-600mm's scalloped control ring. For sports photography, you can use it to record distance to a specific position on the field, and for wildlife, you can target a branch or other spot where a critter is likely to stop and pose for a photo.

(Credit: Jim Fisher)

Power Focus drives manual focus electronically. It supports smooth, slow focus racks and is an appealing option for videographers who want to shift focus from one subject to another for narrative effect. It's also handy if you want to give the autofocus system a helping hand, whether it be to cut through foreground branches to hone in on an animal or simply bring the subject closer in view to speed up initial acquisition. I personally prefer to use the standard manual focus ring for this, and in Sony E the 300-600mm supports full time Direct Manual Focus (DMF) when the camera is set to autofocus, but in L-mount the manual focus ring only works when the camera is set to manual focus.

(Credit: Jim Fisher)

Aside from that, the controls are as expected. The zoom ring is located in the middle of the barrel and has a little "spare tire waistband" bump that makes it both easy to find by touch and comfortable to manipulate. The manual focus ring is just behind the zoom ring. The lens also has four function buttons, positioned just ahead of the control ring. The buttons all perform the same function (configurable via the camera menu for both E and L systems), but are repeated so you can find one in the same relative place regardless of camera orientation. 

Autofocus: Speedy Results, Depending on Your Camera

Sigma uses its fastest high-response linear actuator (HLA) autofocus motor in the 300-600mm F4, which makes sense given the typical use cases: fast-moving action in team or individual sports and unpredictable wildlife. I checked the focus speed with the Panasonic Lumix DC-S1R II set to AF-S mode and noted nearly instant response when focusing on near and distant subjects.

(Credit: Jim Fisher)

Photographers will typically use a lens like this in AF-C, which checks for focus for every image in a burst, not just the first, like AF-S. I noticed slower focus response with the S1R II in AF-C, not just with this lens, but with others, which is the same experience I had with the Lumix S5 II and the Sigma 60-600mm zoom when I reviewed them together. Sony photographers won't have to worry about this as its autofocus system doesn't slow down in AF-C like Panasonic's.

(Credit: Jim Fisher)

This calls attention to an issue that's more about the camera systems than the lens. The L-mount edition is unrestricted—it works with teleconverters and with any focus drive speed a camera can handle. But what camera to use? Panasonic's current generation autofocus system isn't on the same level as what Canon, Nikon, and Sony offer. Leica makes L-mount cameras, but bodies like the SL3 and SL3-S are prohibitively expensive, and Sigma's compact fp and BF cameras aren't meant to be used with a big lens.

(Credit: Jim Fisher)

On the other hand, Sony cameras provide best-in-class autofocus. When I use a newer body like the a1 II for wildlife or sports photography, I know I'll only have to worry about an occasional focus miss. But without teleconverter support and with a maximum 15fps tracking speed, the 300-600mm loses some of its luster. I don't personally mind the drive speed, as 15fps is still quite fast after all, but I find the lack of teleconverter support more of a problem for this particular lens. I'm always after more zoom power and light gathering for bird photography, and the idea of matching this lens with a 1.4x rear converter to turn it into a 420-840mm F5.6 has loads of appeal, especially when you consider the closest lens in the Sony catalog, the FE 400-800mm F6.3-8 G OSS, has a dimmer aperture. Unfortunately, teleconverters aren't an option for Sony photographers who opt to use third-party lenses like this.

(Credit: Jim Fisher)

Some zoom lenses do decent double duty for macro work, but the Sigma 300-600mm Sports is tuned for distant subjects. Measured from the sensor, the lens focuses as close as 9.2 feet at 300mm and 14.8 feet at 600mm. At best, the lens captures subjects at 1:5.9 life-size, which falls short of the 1:3 we want to see from a zoom to call it a macro. If you want a telezoom with closer focus, the Sigma 150-600mm Sports is among the most versatile; it focuses for 1:2.9 at its 180mm focal length.

Optical stabilization is a necessary feature for a telephoto lens, so of course, it is included in the 300-600mm. Its OS system is rated for up to 5.5 stops of compensation and has settings for general purpose photography (Mode 1) or scenes where you're panning horizontally to follow a subject in motion (Mode 2).

(Credit: Jim Fisher)

Image Quality: Clear, Sharp Optics

I tested an L-mount copy of the 300-600mm F4 Sports with the 44MP Panasonic Lumix DC-S1R II. The lens proves to be a little challenging to benchmark with Imatest due to the size of my testing space and charts. When zoomed to 450mm or beyond, the angle of view is too tight for me to frame the larger of my two lens test charts, and at 450mm to 600mm, I wasn't able to focus closely enough to frame my smaller test tightly, which is enough to skew the results. I was able to get valid data at 300mm, where the lens scores near the top of the excellent range for a 44MP camera from f/4-8 (4,400 lines).

(Credit: Jim Fisher)

Still, thanks to the wonders of burst capture and a couple of opportunities to use the lens for wildlife photos in busy habitats, I took more than 1,500 images, most toward the longer end of the zoom range. I cannot see an appreciable drop in quality between focal lengths. I can see the texture in the plumage of birds and fur of larger animals, and all the other little details that bring a photo to life. The 300-600mm delivers clear, sharp images in the field, and is more than good enough for high megapixel cameras.

(Credit: Jim Fisher)

You may be tempted to leave the 300-600mm's huge hood at home to cut some weight and make the lens a little less awkward to handle, but it's worthwhile to use on sunny days. The zoom has a humongous front element and will show flare if the sun hits the glass from an angle. The hood is deep enough that you won't have to worry about flare apart from scenes where the sun is in view behind your subject.

(Credit: Jim Fisher)

Raw images captured with the zoom show slight pincushion distortion through the entire focal range. The distortion draws straight lines with a slight inward bow, but is easily correctable. Adobe already has an automatic correction profile available for its popular Lightroom and Lightroom Classic applications. For JPGs, the distortion is removed automatically by your camera's image processor.

(Credit: Jim Fisher)

The lens's F4 super telephoto optics capture photos with an extremely shallow depth of field for soft, defocused backgrounds. Sigma's defocused highlights show a slight soap bubble effect at the edges, take on a cat's eye shape at f/4, and display a nominal amount of false texture or color. The Sigma delivers good-looking bokeh, with a hint of a busy, frenetic look in scenes with complex, repeating backgrounds, quite similar to what I saw from the Sony FE 600mm F4 GM OSS.

(Credit: Jim Fisher)