In this video, I take a deep dive into a lens that's been a staple in my kit for over a decade – the Sigma 120-300mm f/2.8 Sport. I’ve used this lens since 2014, and even in 2025, it's holding strong and delivering incredible results on modern mirrorless bodies like the Canon R5 and R3.

I’ll walk you through:

✅ Why I originally picked up this lens back in the DSLR days

✅ Real-world performance using Canon’s EF-RF adapter

✅ How it handles for action photography, wildlife, and events

✅ Image quality, autofocus, and overall handling in 2025

✅ Why it still deserves a spot in your bag — or on your radar — today

Whether you’re a longtime EF shooter or just curious how older glass holds up on RF bodies, this one’s for you.

Why the Sigma 120-300mm f/2.8 Sport Is Still a Beast in 2025

Hey everyone, it's Tim here—and today I want to share my thoughts on a lens that’s been a loyal part of my kit for a very long time. I’m talking about the Sigma 120-300mm f/2.8 Sport. Yes, it’s big and heavy, but even after all these years, it remains one of my most prized lenses. I've had it since its release in 2014, which means it's been with me for over a decade.

A Brief Overview: Quick Specs

Sigma 120-300mm f/2.8 DG OS HSM Sport

• EF mount
• Full-frame coverage
• Constant f/2.8 aperture
• Optical stabilization (OS)
• Weather-sealed magnesium alloy construction
• Approx. weight: 3.4kg (7.5 lbs)
• Originally designed for DSLR bodies like the Canon 1DX

Why I Bought It

This lens has truly stood the test of time. I actually started out with one of the earlier versions that didn’t have optical stabilization. Back then, I had just upgraded from the Sigma 100-400mm—a much older lens that frankly didn’t meet my expectations in terms of sharpness. I was disappointed with the results and needed something better.

That’s when I picked up a used version of the 120-300mm f/2.8 without stabilization. It wasn’t perfect, but it was a step up. At the time, I was working as a staff photographer at a dog training ground—a very different world from what I do now as a wedding and lifestyle photographer.

In 2014, the original lens I had broke down, and I ended up replacing it with the current version of the Sigma 120-300mm f/2.8 Sport. And let me tell you, it's still performing incredibly well in 2025.

How It Performs on the Canon R5 & R3

Pairing this lens with the Canon R5 or R3 using the EF to RF adapter works better than you'd expect. Autofocus is responsive, tracking is reliable, and the image quality still holds up against newer glass. No, it’s not a native RF lens, but the performance is consistent and usable even in challenging conditions.

On the Canon R3, eye detection and animal tracking work surprisingly well. I tested it at a local dog agility event, and the R3 had no trouble locking focus, even with fast subjects. The R5 also performs well with this lens, although you do need to manage the buffer when shooting long bursts.

Real-World Use Cases in 2025

While I no longer use this lens for weddings due to its size and weight, it remains unbeatable in other situations:

🐦 Wildlife photography: Great reach, fast autofocus, and beautiful bokeh.

⚽ Sports/action: Tracks movement well with modern Canon bodies.

🎓 Graduation ceremonies: Perfect for distant candid shots.

🎶 Concerts/performances: Excellent low-light performance.

Compared to Modern Alternatives

Lens | Aperture| Price (CAD) | Weight | Native to RF?

Sigma 120-300mm | f/2.8|~$2,500 used | 3.4 kg | No

Canon RF 100-300mm | f/2.8 | ~$13,000 | 2.95 kg | Yes

For many photographers, spending $13K on a new RF lens just isn’t feasible. That’s where the Sigma shines: for a fraction of the cost, you get comparable image quality and flexibility.

Final Thoughts

If you're thinking about buying one used, or you already own it and are wondering whether to keep it, I say don’t let it go. It's a solid investment, even in today’s mirrorless world. You just can’t beat the performance-to-price ratio.

Whether you're a wildlife photographer, a sports shooter, or someone who simply wants a reliable telephoto zoom for your Canon mirrorless system, the Sigma 120-300mm f/2.8 Sport still deserves a place in your bag.