Canon RF-S 10-18mm vs EF-S 10-18mm | The Best Ultra-Wide Lens For Canon?

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When it comes to finding the perfect ultrawide lens for your crop-sensor RF-mount cameras like the Canon R50, R100, R10, and R7, the choice often boils down to two contenders: the newer RFS 10-18mm f/4.5-6.3 and the older EFS 10-18mm f/4.5-5.6 (with an adapter). Let’s dive into a detailed comparison to determine which lens deserves a spot in your camera bag.

Physical Differences

• Size & Portability:

  • RF-S 10-18mm: Compact and lightweight at just 5.3 oz and slightly over 2 inches when retracted.

  • EF-S 10-18mm: Bulkier at 8.5 oz (with the RF adapter) and nearly 4 inches long.

• Build Quality:

  • RF-S: Prioritizes portability with a plastic build; great for on-the-go photography.

  • EF-S: More robust but heavier, thanks to its larger form factor.

• Convenience:

  • RF-S: Requires unlocking before use, reducing storage size.

  • EF-S: Includes physical switches for autofocus/manual focus and stabilization, offering quick adjustments.

Technical Specs

• Aperture Range:

  • RF-S: f/4.5-6.3; slightly slower at 18mm, but not a significant drawback.

  • EF-S: f/4.5-5.6; offers better low-light performance at the telephoto end.

• Autofocus:

  • Both feature STM motors for smooth, silent focusing, but the RF-S edges ahead in speed.

• Image Stabilization:

  • Both provide up to 4 stops of stabilization—perfect for handheld shots and video.

• Filter Thread Size:

  • RF-S: 49mm.

  • EF-S: 67mm.

• Macro Abilities:

  • RF-S: Exceptional close focus; subjects can be as close as the glass element.

  • EF-S: Impressive but not as extreme as the RFS.

Image Quality

Sharpness

• RF-S:

  • Center: Sharp wide open; stopping down doesn’t improve much.

  • Corners: Sharpen up by f/8 but soften at f/11.

• EF-S:

  • Center: Sharp wide open; peaks at f/8.

  • Corners: Softer and more distorted, especially when stopped down.

Vignetting

• RF-S: Slightly more pronounced but easily correctable in post.

• EF-S: Minimal and less noticeable.

Flaring

• Both lenses handle flaring moderately well, with the RF-S showing slight improvements over the EF-S.

Recommendations

• Choose the RF-S 10-18mm if:

  • You prioritize portability and don’t want to bother with an adapter.

  • Close-focus capability is a must for your creative needs.

  • You’re buying new for an RF-mount camera.

• Stick with the EF-S 10-18mm if:

  • You already own it and don’t need extreme close-focus or lighter weight.

Final Verdict

The RFS 10-18mm emerges as the winner for RF-mount cameras, offering better portability, modern features, and improved sharpness. However, the EFS 10-18mm remains a solid performer, especially for those upgrading gradually to RF systems.