Using the Sigma RF 18-50mm f/2.8 on the Canon R5, My Real-World Review
I recently got my hands on the Sigma RF 18-50mm f/2.8 DC DN and threw it on the Canon R5 to see how it holds up in real-world shooting. This lens is getting a lot of attention because of its small size, fast aperture, and relatively low price. So I wanted to test it out in the way I’d actually use it — specifically for video, documentary work, and gimbal setups.
Here’s what I learned.
Compact Size, Big Potential
Right away, the size and weight of this lens are game-changers. On the Canon R5, which isn’t exactly a lightweight body, the Sigma RF 18-50mm f/2.8 balances surprisingly well. It feels almost like you’re shooting with a mirrorless APS-C setup. If you're someone who does long handheld shoots, travel work, or uses a gimbal, that compact build makes a big difference.
Ideal for Gimbal Work
One of my favorite use cases for this lens was running it on a gimbal. Even though it’s not an internal zoom, it’s so lightweight and compact that I didn’t need to rebalance when zooming — at least when using it on something like the DJI RS3. The motors on that gimbal are strong enough to compensate for the slight shift in weight as you change focal lengths. That’s a big time-saver when you’re moving fast and don’t want to stop everything just to re-tune your rig.
The constant f/2.8 aperture also helps in lower light and gives you some nice background separation, even on the wider end. It’s a great lens for gimbal work, weddings, events, or doc-style b-roll where you want to stay light and mobile without giving up performance.
But No Manual Focus Switch?
Here’s my biggest gripe: no manual focus switch on the lens. That’s a major drawback, especially for video shooters who like to flip between auto and manual quickly. Yes, you can switch it in the Canon R5’s menus, but it’s buried and awkward to access mid-shoot. I ran into a few situations where I wanted to pull focus manually on the fly, and not having that switch was a noticeable pain.
This one omission makes the lens feel a bit more “consumer” in design, even though the optics are solid. It’s not a dealbreaker, but definitely something you need to work around if you rely on manual focus in your workflow.
Image Quality and Autofocus
In terms of sharpness and color, the Sigma punches well above its weight. It’s crisp across the zoom range, and even wide open at f/2.8, I was impressed by the contrast and detail. Colors render naturally with a slight pop, and I didn’t notice any major chromatic aberration or edge softness.
Autofocus was fast and reliable on the Canon R5 in both photo and video modes. I tested face tracking and subject tracking while walking with the camera, and it held pretty strong. That said, I wouldn’t necessarily recommend it for super fast action or sports — but for most doc-style and narrative work, it performed great.
A Great Tool with One Big Quirk
If you’re a video shooter looking for an affordable, compact zoom that won’t weigh you down on a gimbal or rig, the Sigma RF 18-50mm f/2.8 is a fantastic choice. It's sharp, lightweight, and versatile enough to be a daily driver for a wide range of work.
But the lack of a manual focus switch is a real consideration, especially if you're used to flipping modes mid-shot or if you frequently use manual focus in fast-paced scenarios.
Final Verdict
The Sigma RF 18-50mm f/2.8 on the Canon R5 is a surprisingly powerful combo, especially if you shoot a lot of gimbal work or need a small kit with big results. It’s not perfect — nothing in this price range is — but for a lens this compact to offer solid sharpness, fast AF, and a constant f/2.8 aperture, I think it deserves a place in a lot of shooters' bags.
If you want to see the lens in action, check out the full video right here.