Canon RF 45mm f/1.2 STM vs Sigma 50mm f/1.4 DG DN Art — What’s the Difference?

Canon and Sigma now both offer fast standard primes for full-frame mirrorless systems, but they cater to very different audiences. The Canon RF 45mm f/1.2 STM is a lightweight, budget-friendly f/1.2 lens that gives photographers access to ultra-shallow depth of field without the luxury price tag.

The Sigma 50mm f/1.4 DG DN Art, on the other hand, is a high-end professional lens designed for Sony E and L-Mount systems — known for its outstanding optical precision, build quality, and autofocus speed.

So, which one delivers better value and performance — the affordable Canon or the pro-grade Sigma? Let’s dive into a detailed comparison.

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⚙️ Overview — Creative Compact vs Professional Precision

Canon RF 45mm f/1.2 STM
Canon’s new RF 45mm f/1.2 STM is designed to deliver the signature “f/1.2 look” — creamy background blur and excellent low-light performance — in a compact, 346 g lens that costs under $500. It’s ideal for creators, portrait shooters, and hybrid users who want artistic depth and light-gathering ability without breaking the bank.

Sigma 50mm f/1.4 DG DN Art
Sigma’s DG DN Art lenses are built for professionals who demand flawless optics and fast, reliable autofocus. This 50mm f/1.4 features 14 elements in 11 groups, weather sealing, dual stepping motors, and razor-sharp image quality across the frame. It’s heavier and more expensive, but it’s also one of the most optically impressive lenses in its class.

In short:

• RF 45mm f/1.2: Budget-friendly, ultra-fast, and expressive.

• Sigma 50mm f/1.4 DG DN Art: Premium build, ultimate sharpness, professional-grade performance.

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📊 Specifications Comparison

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🧱 Build and Handling

The Canon RF 45mm f/1.2 is impressively light and compact for such a fast aperture lens. Its plastic build helps keep weight under 350 g, making it ideal for travel or everyday carry. It features both a customizable control ring and a dedicated focus ring, giving it solid ergonomics despite its entry-level price.

By contrast, the Sigma 50mm f/1.4 DG DN Art feels every bit the professional lens it is — dense, durable, and refined. Its all-metal construction, tactile aperture ring, and full weather sealing make it suitable for demanding environments and professional use.

Verdict:

• RF 45mm f/1.2: Compact and accessible.

• Sigma 50mm f/1.4 DG DN Art: Premium build with pro handling.

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🎯 Autofocus and Performance

The RF 45mm f/1.2 uses an STM motor that provides smooth, silent focusing for both stills and video, but it’s not as fast or precise as Canon’s USM or Sigma’s HLA systems. It performs well for portraits and casual shooting but can occasionally hunt in low contrast scenes.

The Sigma 50mm f/1.4 DG DN Art features dual HLA linear motors, delivering blazing-fast, silent autofocus that’s perfectly suited for high-speed photography and hybrid video work. It locks onto subjects instantly and tracks flawlessly, even in challenging conditions.

Verdict:

• RF 45mm f/1.2: Great for everyday use, slower AF tracking.

• Sigma 50mm f/1.4: Top-tier autofocus for pros and hybrid creators.

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🧠 Image Quality

Sharpness

The Sigma 50mm f/1.4 dominates in optical precision — sharp from center to corner even wide open, with excellent contrast and minimal aberrations. The RF 45mm f/1.2, while sharp in the center, exhibits softer edges and more vignetting at f/1.2 — though this contributes to its artistic “character.”

Bokeh

Both lenses produce stunning background blur, but in different ways. The RF 45mm f/1.2 delivers an exceptionally shallow depth of field with “characterful,” slightly swirly bokeh that gives portraits a cinematic feel. The Sigma 50mm f/1.4, with its 11 rounded blades, offers smoother, more neutral background blur — cleaner, but less “dreamy.”

Color and Contrast

The Sigma 50mm f/1.4 produces more neutral tones with high micro-contrast, perfect for commercial work. The Canon RF 45mm f/1.2 leans warmer, with softer contrast and a more expressive, filmic rendering.

Verdict:

• RF 45mm f/1.2: Expressive, creative image quality with strong character.

• Sigma 50mm f/1.4: Technically perfect, clean, and professional.

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🎥 Video Performance

The RF 45mm f/1.2 performs well for handheld video, with smooth focus transitions and quiet operation. However, it lacks optical stabilization and relies on IBIS-equipped bodies for steady footage. Its shallow f/1.2 look adds a cinematic edge for content creators.

The Sigma 50mm f/1.4 is built with filmmakers in mind. It offers minimal focus breathing, clickless aperture control, and near-silent focusing — making it one of the best fast 50s for hybrid work. It’s heavier but far more versatile for professional video use.

Verdict:

• RF 45mm f/1.2: Best for creative handheld or cinematic looks.

• Sigma 50mm f/1.4: Best for hybrid professionals and filmmakers.

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💰 Price and Value

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The Canon RF 45mm f/1.2 is the clear winner in value. For under $500, it gives you f/1.2 performance and a level of bokeh you can’t get anywhere near that price.

However, the Sigma 50mm f/1.4 DG DN Art earns its premium price with superior sharpness, autofocus, and durability — ideal for commercial or professional hybrid shooters.

Verdict:

• RF 45mm f/1.2: Best for creative enthusiasts and budget-conscious creators.

• Sigma 50mm f/1.4 DG DN Art: Best for professionals who need flawless results.

Check availability and price on Amazon 🛒

📷 Canon RF 45mm f/1.2 — Amazon USA / Amazon Canada / Amazon UK / Amazon Australia

📷 Sigma 50mm f/1.4 DG DN Art — Amazon USA / Amazon Canada / Amazon UK / Amazon Australia

Note: camerafight.com participates in the Amazon Associates Program. As an Amazon Associate, we earn from qualifying purchases.

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🏁 Final Verdict — Which One Should You Buy?

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✅ In short:
If you’re looking for a lightweight, affordable, and artistic lens that delivers the f/1.2 “look” without the f/1.2 price, the Canon RF 45mm f/1.2 STM is unbeatable for the money.

If you’re a professional or hybrid creator who demands perfect sharpness, premium build, and reliable autofocus, the Sigma 50mm f/1.4 DG DN Art is the better investment.

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💡 Pro tip:

Pair the RF 45mm f/1.2 with a Canon EOS R6 Mark III or R5 to take full advantage of its low-light potential and IBIS stabilization.
Sigma’s 50mm f/1.4 DG DN Art, meanwhile, performs flawlessly on Sony’s A7 IV or Panasonic’s S5II — where it becomes a true hybrid powerhouse.