Here are some examples of how this lens behaves, especially in astrophotography and infrared photography. The tested lens is Sigma 50mm F1.4 DG HSM Art for Sony E-mount.

Index

1. Motivations to get it
2. Astrophotography: sharp and clear from corner to corner
3. Infrared photography, homogeneous without unpleasant red dot
4. Resolution and flares
5. Weather protection
6. Conclusion: Pros and Cons

Motivations to get it

This is the second copy I have of this lens, the first was for Canon and when I said goodbye to everything Canon I owned I went back to purchase a new Sigma 50mm 1.4 ART lens for Sony. So, I like this lens. And when someone asks me about a 50mm lens I say “this lens”. The next thing they ask me is why? And to save me the time of repeating it more times, I put it here so they can see it and read it as many times as they want.

This lens is not only good for astrophotography and infrared photography, but also for many others fields: wedding photography, travel, fashion, etc.

About the Sigma brand

They are honest:

• Made in Japan. They do not enslave anyone, they pay decent wages and work in good conditions, they comply with environmental regulations. It’s important.
• They sell it at a fair price. The accessory disappears, even the colored box that occupies unnecessary space and also pollutes has been removed, being replaced by a simple and foldable one. If you are one of those who buy a lens thinking about the status it will give you when others see you with it, and you pay 3 times its real price, you should know that you have fallen into a very old marketing trap. In fact, it is not cheap at all compared to Canon, Nikon or Fuji. But its quality matches much higher priced lenses.
• The quality controls work: the objectives come heavily reviewed. They spend time on those things.
• Its CEO puts the face. Sigma CEO exposes his honor in the products he presents. With Sony, the experience I’m having, it’s all so impersonal. They do not recognize the mistakes they make (Sony A7III early dead or problems with the Sony Distagon 35mm 1.4), they leave customers abandoned with a relation based into increase the friction ratio fro complains. At least with Sigma I can tweet the CEO and tell him what’s going on.

Astrophotography: sharp and clear from corner to corner

Sigma claims about this lens that:

…we have minimized sagittal coma flare, chromatic aberration, and every other type of optical aberration that affects image quality.

https://www.sigma-global.com/en/lenses/a014_50_14/

A picture is worth a thousand words. Next I determined a region of the sky and I took several photos of the same area changing the aperture of the diaphragm in the following values: 1.4 – 1.8 – 2.0 – 2.8 – 4.0. I kept the exposure time constant at 10s and varied the ISO to compensate. This is the image I have taken:

and from there I am going to show details of the corner, center and in between of these.

100% Corner cropping

Upper left corner

100% Middle area cropping

Halfway between the corner and the centre.

100% Centre

The sharpness and detail offered by this lens make it a great solution for astrophotography.

Infrared photography, homogeneous without unpleasant red dot

This lens maintains a very smooth image across all apertures. It takes a long time for the unpleasant red dot to appear, which makes some lenses for infrared photography unusable. This is not the case. This lens is great for infrared photography.

Below, the same frame with different apertures of the diaphragm. Filter HOYA Infrared R72:

Resolution and flares

Sigma claims as feature that this lens achieves high resolution. As we have seen before, a diaphragm opening of 1.4 is the one that manifests the most defects. Even so, I was able to see the satellites of Jupiter from a detail of a photo with aperture 1.4.

And with the sun facing the lens, flare is kept to a minimum and details come through perfectly. Color rendering is also superb. Look at the following example:

Weather protection

Sigma, in its version for Sony E mount, incorporated some improvements to reinforce its protection against dust and humidity. Here you can see the presence of a rubber ring to improve the seal between lens and body.

The Canon mount version didn’t have it (at least the one i had), but still this lens is so well built that it’s not easy for anything to get inside.

Conclusion: Pros and Cons

Pros: State of the ART lens, superb detail. Fair product from honest company.

Cons: Heavy, but not more than other usual lenses (the same size and weight than a 24-105mm).