In this test, we will take a closer look at the rather popular lens – Sigma Super-Wide 24mm F2.8. It is one of the smallest 24 mm lenses and weights 194 grams (without caps). It is also quite cheap. With a bit of luck, you can buy it for around 50-60 EUR with highest prices between 80 and 90 EUR. This lens was not considered optically good by most users, but rather was perceived as an average, cheap alternative to the more expensive 24s. Is it worth buying?
Vignetting test shows that there is strong light fall-off at F2.8 and F4. This is expected on wide angle lenses, especially on full frame sensors (Sony A7 mark II was used this tests). At F5.6 vignette is still quite strong and lens must be stopped down to F8 for it to become acceptable. Unfortunately it is not entirely gone at higher aperture values and is visible in extreme corners even at F22. Colors are nice and neutral. No color casts at all. Contrast is good.
Center of image is sharp from wide open with mid sections sligthly soft and corners extremely soft up to F5.6. At F8 mid sections are sharp and corners are acceptable but extreme corners are soft up to F16. For a decent sharpness across whole image I’d suggest not to go below F11. Sharpness is definitely not one of strenghts of this lens. Additionally my copy, like previously tested Vivitar 19mm F3.8 has a bit better sharpness on left side. Soft corners have heavy ghosting. There is small barrel distorion in center while corners look typical for pincushion distortion, again it is similar to Vivitar 19mm F3.8. This kind of mixed distortion is quite hard to fix.
At price range of 80-90 EUR you can easily get 24mm lens with better sharpness, less vignetting and more controllable distorions. It will hovewer be a bit bigger, heavier and with longer minimal focusing distance (18 cm for sigma vs about 30 cm for other lenses).If you rarely go below F8 and don’t use wide angle for architecture shots it is still worth to buy this lens if its price tag is 60 EUR or less. It is also quite good performer on APS-C sensors as you won’t be that much affected by vignetting and corner softness.
Be sure to check sample images.