With the introduction, in 2010, of the Mark II EF300mm f/2.8L IS USM, Canon created a problem – if you have the Mk I version of the lens, is it worth upgrading? Equally, if you are looking to buy should you pick up a cheaper Mk I or the more expensive Mk II? And finally, is f/2.8 really worth it when there is also the EF300mm f/4L IS USM lens available substantially cheaper? Putting them side-by-side on an EOS 5D Mark II, it is easy to see where the sensible money should be spent.
Looking first at the overall score, it seems that price is an indicator of performance – the Mk II version scores 28.5 to the MkI’s 24.8 and the 300mm f/4L’s 17.2 – all three of which are very good scores. Equally, if we look at the P-Mpix scores, the EOS 5D Mark II has a nominal score of 21 P-Mpix. Using the EF300mm f/2.8L IS II USM, the score is 20.5P-Mpix so barely any reduction in quality, with the EF300mm f/2.8L IS USM it’s 17.2P-Mpix and with the EF300mm f/4L IS USM, it drops to 12.8 P-Mpix. Clearly, in terms of resolution, the two f/2.8 lenses win out.
Looking at the field map, both f/2.8 lenses show exceptionally good resolution across the frame, with the Mk II version just beating it’s older sibling. With the aperture set to f/4, the EF300mm f/4L IS USM puts in a good performance, but it can’t match the two more expensive models. However, once the aperture is stopped down to f/5.6, the differences between the three lenses are less apparent. The EF300mm f/2.8L IS II USM is still the best, showing the best edge-to-edge resolution, however between the MkI lens and the f/4L version, there is little difference. Once the aperture closes down to f/11, the differences have all but gone, with all three lenses putting in equally good scores.
It’s almost exactly the same story with the vignetting scores. The EF300mm f/2.8L IS II USM is the best of the trio, showing the least vignetting at both f/2.8 and f/4. Once again though, from f/5.6 all the way through to f/32, all three lenses show no vignetting at all.
As with the Mark I EF300mm f/2.8L IS USM, both the Mark II and the EF300mm f/4L IS USM show no chromatic aberration or distortion either.
In reality, both f/2.8 lenses are exceptional performers and the f/4 model is not that far behind given the price differential.
Attached to the APS-C sensored EOS 7D, the EF300mm f/2.8L IS USM once again puts in a strong performance, scoring a DxOMark score of 17, relative to the EOS 7D’s resolution of 18megapixels. Equally, the Pentax lens scores very well, managing 15 compared to the 16.3megapixels available on the K-5. Overall, this shows the EF300mm f/2.8L IS USM is as good as it’s made out to be, but in this comparison, the Pentax on a K-5 is not that far behind.