The Sony 24mm f/1.4 GM promises high resolution and sharpness as well as low spherical and chromatic aberration. At nearly $1,400, the lens is quite a bit more expensive than similar focal length offerings from Sigma and Samyang. Is it worth the premium?
Alyn Wallace field tested the Sony lens, comparing it against his existing Samyang 24mm f/1.4. Wide open, the Sony lens delivered impressive results, with excellent sharpness through most of the frame. There was a strong vignette to the corners, which is almost inherent to all fast and wide lenses, particularly ones with smaller front elements. Aberrations, which can dramatically impair the quality of astro images, were decently well controlled. Stopped down to f/2.8, the lens improved even more. Vignetting decreased and the far corner's aberrations improved. Overall, the lens performed drastically better than the Samyang when wide open.
The Samyang improved dramatically when stopped down, and surprisingly gave the Sony lens a run for its money at f/2.8. I found this surprising given the over $800 price difference between the lenses. While the corners are still not as well corrected as the Sony, I was surprised just how close it was throughout most of the frame.
Wallace, based on the results he observed, called the Sony potentially one of the best astrophotography landscape lenses around. I think that is definitely a fair assumption based on the strong showing in the tests.
Unless you are a dedicated astrophotographer, or would have other uses for a fast 24mm lens, I think the Samyang is definitely worth considering. At only $550, it is a much cheaper option to get started in astrophotography.