This is a very unscientific comparison of 3 Legacy 24mm Lenses and the Sony 16-50mm Kit Lens (@ 24mm). I didn’t have a Kit lens in the 24mm range for full frame E-Mount, so there is no kit lens comparison on full frame.
All images below are crops from JPGs direct from the camera with sharpness turned down as far it will go (-3).
In all cases, aperture is set to f8, ISO is at 100, white balance is on the cloudy preset and I have manually focused to the distant houses at the centre of the image. A remote was used in all cases, the full frame shots were all taken at 1/400s and the APS-C ones at 1/500s.
The Lenses tested are:
Sigma Super-wide 24mm f2.8 FD Mount
Sigma Super-wide II 24mm f2.8 PK Mount
Canon FD 24mm f2.8
Sony 16-50mm f3.5-5.6 SELP1650
The Full Frame Camera is a Sony A7s and the APS-C Camera is a Sony a5100.
Full Frame Centre Crops
From these samples, there doesn’t appear to be too much difference between the three lenses at the centre, however in other situations, I have found the Canon FD 24mm to be sharper, though this may have been due to lack of contrast or increased aberration in the Sigmas. The Canon is also noticeably darker at f8.
Full Frame Edge Crops (Left side)
At the extreme left side of the frame, there isn’t much to choose between the Canon FD and the Sigma Super-wide II, though the Canon suffers from less chromatic aberration. In practice, I have found the Sigma Super-wide II to be slightly sharper than the Canon at the sides. The original Sigma Super-wide clearly performs worse than the other two at the sides.
Full Frame Corner Crops (bottom right)
Again, not a great deal to choose from between the Canon FD and the Super-wide II at the corners. Perhaps slightly more Chromatic Aberration on the Super-wide II, and perhaps the Canon is slightly softer. The original Super-wide has just turned to mush.
APS-C Centre Crops
On the 24MP APS-C Sensor, the Canon FD 24mm starts to look a little softer, though it is possible that it is not correctly calibrated to infinity with this adapter (the lens was at ‘hard’ infinity for this photo). There’s not a lot to choose from between the other 3, and the Sony is benefiting from in-camera correction. I think that I’d call this a tie between the Sony and the Super-wide II.
APS-C Edge Crops (Left Side)
Even on APS-C, the sides are considerably worse than the centres on the manual lenses with chromatic aberration in all three. The original Super-wide is clearly the worst performer here, with the Canon FD and Super-wide II showing similar performance. The Sony, benefiting from in-camera correction is the clear winner here.
APS-C Corner Crops (Bottom Left)
Again, not much to choose between the Canon FD 24mm and the Sigma Super-wide II, both showing similar chromatic aberration. The original Sigma Super-wide is clearly the loser and the in-camera-corrected Sony, the winner.
On Full-frame, there isn’t much to choose between the Canon FD and Sigma Super-wide II, in practice I found the Canon to be sharper in the centre, but the Super-wide II to be more consistent across the frame. This may not appear to be the case in the above images, though this may be due to an issue focusing to infinity with the adapter (I will make a future post about the inconsistencies in adapters). The Sigma Super-wide II is the widest of the three, the original Super-wide has the narrowest field of view.
The Super-wide II tends to be cheaper than the Canon, so it probably represents better value (if you can find one). The original Super-wide should be avoided at all costs!
On APS-C, the Sony has an unfair advantage with in-camera correction. Even so, the 16-50 Kit lens performs surprisingly well at this focal length, so there’s probably not much point in getting a manual 24mm lens if you have the kit lens (though a manual focusing ring is much easier to use than the focus-by-wire ring on the Sony).