Sigma 14mm f/1.4 DG DN lens review — the ultimate lens for astrophotography

The SIGMA 14mm DG DN f/1.4 lens caused shockwaves upon its initial release. Never before had a lens been coupled with apertures such as f/1.4, and at 14mm. As the latest in cutting-edge technology, it would prove to be an overall game-changer for astrophotography, allowing more light into our cameras and revolutionizing complex compositions of night sky images, coupling landscapes with starry skies above.

With astrophotography, we need to let as much light into our cameras as possible, in order to resolve the finer details in our night-scape images. With lenses previously at the threshold of f/2.8–f/1.4, light gathering was acceptable, but resulted in adjustment of other camera settings — including shutter speed and ISO values — to generate a low-light image. Now, with f/1.4, it is possible to execute sharper, more defined images than ever before, and it has certainly proved to be a lens worthy of a place in any photographer’s camera bag.

Sigma 14mm f/1.4 DG DN review

Sigma 14mm f/1.4 DG DN: Design

• Heavier lens
• Excellent lens build
• Weather-sealed design

With a weight of 41.3 ounces (1,170 grams), this lens is much heavier than many of its rivals. Therefore, it is best used while supported on a static tripod. It can be used handheld, but the weight can restrict usage time.

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Sigma goes a step above and beyond to produce quality optics of a professional grade. From machining to material choice and brand representation, each lens is like an art form of its own, and attests to a quality lens choice.

There are a series of buttons and switches on the 14mm DG DN, including Focus Mode (to switch between Manual and AutoFocus), Manual Focus Lock (to disable the focus ring), AFL (a button that can be customised based on camera body operation) and Aperture Click (to disable aperture click when adjusting this figure on the barrel of the lens),

Filters can be used in different ways, from an adapter attached to the front of the lens (for the use of glass filters directly in front of the lens) to the built-in rear filter holder. Filters (which are approximately the size of an SD card) can be positioned between the camera and lens, and the supplied lens cap has compartments to house up to two filters.

This 14mm lens has been designed with weather resistance in mind. Featuring a dust- and splash-resistant construction, it suitable for use in rugged environments and inclement weather. However, the lens is not fully waterproof, and direct contact with water is not advised.

The lens comes with a one-size, detachable L-mount that can be used to house the lens if attached to a static tripod. The mount comes with a universal 0.25 inch (6.3 mm) screw thread to accept the majority of universal tripod attachments.

Sigma 14mm f/1.4 DG DN: Performance

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• Excellent light-gathering capability
• Sharp results at the corner of the frame
• Chromatic aberration corrected from previous model

This test image captures a field of sunflowers under the arms of the Milky Way — taken at varying apertures of f/1.4 to f/4. Taken at a hyperfocal distance of 4.67 meters, the majority of the scene is in focus, except for a few subjects closer than half the hyperfocal distance, for which focus stacking was necessary when shooting at this aperture. Sharpness is excellent as enough light can enter the camera to perform an accurate focus on the stars in-frame — we used the LCD monitor to digitally zoom in on a star and fine-tune the focus.

At f/1.4, vignetting is more evident; however, this is the nature of shooting at such a wide aperture. This can be corrected in photo-editing software such as Lightroom, where the lens profile can be applied, or you can perform manual adjustments. As you decrease the aperture, vignetting becomes less apparent; however, adjustments need to be made for your other camera settings, resulting in introduced artefacts, such as noise.

Compared to its predecessor, the Sigma 14mm F/1.8 DG HSM, chromatic aberration has been significantly improved. Stars are more round and sharp at both corners and edges of the frame, and there's no loss in detail through varying apertures.

Color reproduction is very good. Not only do the lens's immaculate light-gathering capabilities reveal fainter structure and detail within the Milky Way, other atmospheric phenomena such as airglow can sometimes be apparent in images — even though the effect may not have been visible to the eye during a night shoot.

Within the context of landscape photography, flaring is not so apparent. Only when directly centering the sun (for the context of sunset photography) is flaring somewhat introduced, depending on how you frame and angle the lens in relation to a bright light source.

Sigma 14mm f/1.4 DG DN: Functionality

• Good autofocus capability for daytime subjects
• Improved signal-to-noise ratio
• f/1.4 at 14mm is a game-changer for astrophotography

The excellent light-gathering capability at f/1.4 at 14mm is a game-changer for astrophotography. Not only does this extra stop let in even more light to your camera, but exposures can also be utilized to increase the signal-to-noise ratio in images. Using much higher ISOs, it is even possible to acquire images of the Milky Way handheld — although standard practice is to utilize a static tripod (or a star tracker for longer exposures).

The lens can also identify deep-sky objects within images at this scale. Images of the moon are identified on a smaller imaging scale and composite images can be deployed to acquire the full visual effect of the lens, for instance as the moon moves throughout the night.

Because this lens gathers much more light, a digital magnifier built into your camera’s LCD monitor can be used to zoom in on a bright star and perform subtle fine-tune focusing. Rocking the focus wheel back and forth will identify pinpoint sources of light.

Autofocus accuracy is good. Working within the camera’s focusing area (we used the Sony A7S II), the images have crisp focus across the frame, with limited chromatic aberration in the corners of the frame.

One notable (and understandable) scenario is that the lens struggles in more light-directed environments. In an example of sunset photography, the lens does not respond well when attempting to identify the subject matter. For this reason, manual focus is highly advised. Overall, autofocus is good within well-lit environments but struggles more in low light, with subjects more challenging to detect.

Even with f/1.4 capability, manual focus is still advised for low-light environments. Even when using an amplified ISO, subject matter can be much harder to detect, or the focus may be somewhat soft. Manual focus, taking advantage of greater light-gathering capability, will provide greater control.

The focus wheel turns very smoothly to obtain critical focus, especially if focus stacking is utilized. This smooth operation makes it possible to obtain crisp images in low-light environments, especially in the context of landscape astrophotography.

Should you buy the Sigma 14mm f/1.4 DG DN?

If you're looking for a quality lens at the very top of its game, with superior light-gathering and revolutionary technology, then this is the lens for you. Yes, it's a more expensive choice, but it is well worth the investment.

14mm is a suitable choice of lens for versatility across a number of photographic genres. The incredible light-gathering capability at f/1.4 adds an element of artistic flair, and so we would vouch for this lens as a must-have in any photographer’s camera bag.

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