Because I believe it is important to understand how your tools work I decided to do a test of my 3 lenses using a googled lens test image.
Canon 24 mm f1.4L USM I (tested f2.8, f4, f5.6, f8, f11 and f16)
Canon 50 mm f1.4 USM (tested f2.8, f4, f5.6, f8, f11 and f16)
Canon 70-200mm f4L USM (tested f4, f5.6, f8, f11 and f16) (tested at 70mm, 100mm, 135mm and 200mm)
When composing the image I placed the test image as close to filling the same amount of frame through out the lenses.
Shutter speed: 1/200
Flash
Tripod
Remotely fired camera
Exposer correction: +/- 0.45 stop at the most – so that all images has a ca centre value of 87 87 87
Forgot to turn of sharpening in Light Room, all images sharpened to: amount 25, Radius 1.0, Detail 25 and masking 0.
White balance correction individually,
– 24 mm shifts from 6550K at f2.8 to 5750K at f16
– 50 mm shifts from 6050K at f2.8 to 5550K at f16
– 70-200 mm shifts 70 mm from 6050K at f4 to 5700K at f16
– 70-200 mm shifts 200 mm from 6050K at f4 to 5700K at f16
– 70-200 mm shifts 135 mm from 6050K at f4 to 5700K at f16
– 70-200 mm shifts 100 mm from 6100K at f4 to 5750K at f16
PREDICTIONS
– Sharpest aperture f8
– Sharpest lens the 50 mm
– Most distortion the 24 mm
RESULTS
24 mm
Is the sharpest lens. Sharpest aperture f8.
The lens with the most vignetting, lens distortion and chromatic aberration
50 mm
The softest lens. Apertures below f4 are significantly softer. Sharpest aperture f8-f16. when compared to 70-200 mm it has least amount of vignetting at the aperture with the most amount, but second worst vignetting at the aperture with the least amount. Second worst for chromatic aberration
70-200 mm
Is the second sharpest lens. Sharpest aperture is f16 through zoom, but softer to the sides, gets exponentially worse. When compared to the 50 mm it has least amount of vignetting at the aperture with the least amount, but second worst vignetting at the aperture with the most amount. Best for not having chromatic aberration except for at 200mm
RESULTS – detailed
– Sharpest aperture
– 24 mm sharpest aperture f8
– 50 mm sharpest apertures f8-16 (f4 and below noticeably soft)
– 70-200 mm sharpest aperture f16 through zoom (centre sharpness the same throughout zoom, going up from 70mm to 200mm the edges get slightly softer)
– Sharpness comparison
24 mm vs 50 mm
– 24 mm is sharper than the 50 mm at aperture f8
– 24 mm is noticeably sharper than the 50 mm in the same apertures below f4
– 50 mm’s f8 is similar to the 24 mm’s f2.8 in sharpness
50 mm vs 70-200 mm
– 70-200 mm’s sharpest aperture f16 is slightly sharper than the 50 mm’s sharpest aperture f8
24 mm vs 70-200 mm
– 24 mm’s sharpest aperture f8 is slightly sharper than the 70-200 mm’s sharpest aperture f16
– vignetting
– 24 mm vignetting apparent below f2.8. At aperture f4 slight black line in bottom right hand corner – reapers, but sutler in aperture f16. Apertures f5.6 and f11 have the lest amount of vignetting, f11 best. f8 seams to have a sutler amount of vignetting.
– 50 mm vignetting apparent below f2.8. At aperture f5.6 same slight black line that appeared in bottom right hand corner of the 24 mm, but not as dominant – it also reappeared sutler at aperture f16. f4 seams to be the aperture with the least amount of vignetting. f8 and f11 the same.
– 70-200 mm vignetting apparent below f5.6. Does not have the black line in bottom right hand corner. Through out the zoom starting at 70mm apertures f8, f16, f16 and f11 have the least amount of vignetting. vignetting becomes more towards 200mm
– Vignetting comparison
24mm vs 50 mm
– Comparing the best apertures for the least amount of vignetting f11 24mm vs f4 50mm – the 50mm has the least
– Comparing the worst apertures for vignetting f2.8 for both lenses – the 50mm has the least
50 mm vs 70-200 mm
– Comparing the best apertures for the least amount of vignetting 70-200 mm has less vignetting throughout out zoom.
– Comparing the worst apertures for vignetting, the 50mm has the least compared to 70-200 mm throughout zoom
– Lens distortion
– 24 mm apparent bulge outwards
– 50 mm Subtle bulge outwards
– 70-200 mm at 70 mm less than the 50 mm – but does change through out zoom – bulges more and more inwards – 100 mm appears to be closest to correct
– Chromatic aberration
– 24 mm, Chromatic aberration not present in the centre, but distinct on the sides, starts appearing ca 5 cm from centre, increases proportionately more towards the edge.
– 50 mm Chromatic aberration not present in the centre, but present on the sides, starts appearing ca 10 cm from centre, increases proportionately more towards the edge.
– 70-200mm Chromatic aberration not present in the centre, but present on the sides at 70 mm, less so 100 mm, non existent at 135 mm, most at 200 mm, starts appearing ca 9 cm from centre, increases proportionately more towards the edge.
– Chromatic aberration comparison
24 mm vs 50 mm
– 24 mm worst
50 mm vs 70-200 mm
– 50 mm ever so slightly worse than 70 mm
– 50 mm worse than 100 mm
– 50 mm worse than 135 mm
– 50 mm better than 200 mm
CONCLUSION
I was wrong about the sharpest lens, but almost correct about the sharpest aperture and correct that the 24 mm had most distortion. I’m not to worried about vignetting, lens distortion and chromatic aberration as it can easily be corrected in raw processing, but sharpness can not be fixed. However I’m concerned about the line that appeared in the bottom right hand corner on the 24 mm and 50 mm at different specific aperture – more investigation required.
24 mm for the sharpest pictures shoot at f8. Avoid aperture f4 because of noticeable black line bottom right hand corner. Use instead of 50 mm when shooting in low light conditions as lower apertures are sharper and likely to have a better depth of field.
50 mm for the sharpest pictures shoot at f8-f16, do not go below f8, f5.6 because of noticeable black line bottom right hand corner. f4 and below because of softness.
70-200 mm for the sharpest pictures shoot at f16, for even sharpness and least amount of vignetting use 70 mm, for best results use tripod.
I was surprised that colour temperature changed depending on the flash strength. Use grey card not only when moving / changing light setup but also when changing aperture.