One of the main reasons people invest in a full-frame camera is for the benefit of full-frame lenses. And as many photographers know, APS-C lenses don’t always measure up. But Sigma is aiming to change that with its new 17-40mm F1.8. Since the claim is bold, we had to test it ourselves.
This is the Sigma 17-40mm F1.8 DC Art, priced at ₹78,000. This lens follows the legacy of Sigma’s iconic 18-35mm F1.8,
launched nearly a decade ago. In this review, we’ll walk you through its performance and whether it’s worth the upgrade.

APS-C on a Full Frame

For this review, we tested the lens on a Sony A7 IV in crop mode (1.5x). You might wonder why—but this also makes sense for newer APS-C bodies like Sony A6600 or Fujifilm XT-5. The lens is available in multiple mounts including Sony E, Fujifilm X, Canon RF and Lumix L.

Look, Build & Feel

As expected from Sigma’s Art series, the build quality is excellent. The lens feels solid in the hand, weighing 535 grams, and is built primarily from metal. Key features include:

• Aperture ring with a click/de-click option
• Aperture auto-lock switch
• Two programmable buttons (top and side)
• AF/MF switch
• 67mm filter thread
• Locking lens hood (standard for Sigma)

It also comes with a metal mount, weather sealing, and “Made in Japan” proudly etched on it. The zoom is internal, meaning the balance doesn’t shift while changing focal lengths—perfect if you’re planning to use it on a gimbal. Minimum focus distance is 28cm, giving you a bit of macro flexibility.

Image Quality

As mentioned earlier we tested this on the Sony A74 body in crop mode with a 1.5x. But we also have featured some images with the A6400 APSC camera – so watch the credits pic info carefully. The 17-40mm on APSC translates to approximately 26 to 60 mm in full frame equivalence which makes this lens versatile and it comes very close to the 24-70mm full frame lens. The F/1.8 aperture on APSC gives you a full frame equivalent depth of field of F/2.8.

The pics in daylight are very vibrant, well saturated and speaks for the quality of the lens. The sharpness and detailing are also good, although occasionally in depth it does add some softness to the sides. What was surprising was that this lens was able to provide great depth – similar to a full frame camera and I think that is its good quality.

Autofocus

While on this subject – lets speak about the autofocus as well. I was impressed by its performance. In our testing the auto focus was very quick both in the low and high focal range. Even with subjects in the foreground the lens focuses fast and delivers sharp results – so that was good to see. The motors are also silent, which adds to the shooting experience and can be important if you want to shoot without getting noticed. In video as well the focusing was smooth and breathing is very minimal, which scores this lens another point in the video category.

Lowlight

As good as the daylight performance was – the lowlight performance was also impressive. Some images were shot with the Sony A6400 – and for most part the images were pretty good. The sharpness and detailing were evident and even in dimly lit conditions the images were decent. Yes occasional detailing while zooming in was missing and some colour shifting was noticed, although colour shifting is more for a sensor.

Macro/Close-up

This lens has a minimum focus distance of 28cm, so this allows you to shoot pseudo macro images and the images are decent. The images in this case are ok. I wouldn’t say it’s a big bonus, but in case if you want to use it then you at-least have an option to shoot with.

Bokeh

Being an F/1.8 lens, at full frame it is equivalent at F/2.8 depth of field. The bokeh is nice to look at, it’s a mix of round and cat’s eyes depending on how light is falling on the subject. I felt the bokeh was better in the lowlight than in daylight in our testing time. But overall a decent performance in this regard.

CA Value

We ran it through Quick MTF and got a score of 0.90. That it fairly high – but in real world application, it is difficult to get that.

Flare and Ghosting

The flaring and ghosting performance of the lens was very impressive. Even in extreme lowlight and at a wide aperture, the lens displayed minimal flaring and ghosting. Yes occasionally there was a slight hint. But nothing of concern.

Conclusion

So what do we think about the Sigma 17-40mm F/1.8 Art lens? The predecessor to this lens was launched nearly a decade back. And it was time that Sigma offered a new replacement. And in most parts I think it delivers well. The focal length is now closer to a full frame 24-70 F/2.8 standard zoom lens. Yes, it is not all great – for instance the CA performance could be better and the lowlight has some room for improvement as well.
But what Sigma is able to deliver is a good daylight performance that it closer to a full frame 24-70 lens. And that I think for any APS-C shooter, this is a vital and worthy upgrade from a kit lens.
Priced at around ₹78,000 this definitely will feel like a full frame lens on your wallet as well. However, if you are looking forward to shooting professional level content on your APSC camera without upgrading to full frame bodies then this, we would say, is an easy choice.