I think it's about time to rethink your rating systems and decide which rating you'd give to the 11-24/4 Canon. It's about time to close the gaps you left with some of the early 50 MP tests, don't you think so?
Also, giving the Sigma 2 1/2 stars optically on 50 MP (and only 3 1/2 at 21 MP, which is rather wrong) while the (worse, due to the flare "magnetism") Nikon 14-24 still keeps 4 raises more than one eyebrow. I exchanged the Nikkor for the Sigma, as it definitely behaves less like a diva in frontlight. nOw I'd like to know what makes the Nikkor half a star better although it's tested on 24 MP and the reduction of these flares is pretty time-consuming and not always fully possible?
"... so front filters are a no-go here" - allow me to question that. No screw-in filters doesn't mean "no front filters", they just need to be big (150×150 mm should do), flat, with a proper holder and in excellent optical quality. That, with 2 or three of these filters can cost something between 40 and 80% of the lens. I use the same holder I purchased for the 14-24/2.8 Nikkor, just with a kind of a spacer.
But the downisde of thses extra holders always is: Are they light tight enough? For big stoppers like ND 3.0 and in bright sunlight it's a relevant question and since most of these stoppers have a more or less massive colordrift, we might look out for other possibilities.
And maybe we also should open a discussion which of these filters still are necessary today? Except for polarizers, I don't see much value of grading filters or medium stoppers, as all these long time exposures can also be done with software.
Also, giving the Sigma 2 1/2 stars optically on 50 MP (and only 3 1/2 at 21 MP, which is rather wrong) while the (worse, due to the flare "magnetism") Nikon 14-24 still keeps 4 raises more than one eyebrow. I exchanged the Nikkor for the Sigma, as it definitely behaves less like a diva in frontlight. nOw I'd like to know what makes the Nikkor half a star better although it's tested on 24 MP and the reduction of these flares is pretty time-consuming and not always fully possible?
"... so front filters are a no-go here" - allow me to question that. No screw-in filters doesn't mean "no front filters", they just need to be big (150×150 mm should do), flat, with a proper holder and in excellent optical quality. That, with 2 or three of these filters can cost something between 40 and 80% of the lens. I use the same holder I purchased for the 14-24/2.8 Nikkor, just with a kind of a spacer.
But the downisde of thses extra holders always is: Are they light tight enough? For big stoppers like ND 3.0 and in bright sunlight it's a relevant question and since most of these stoppers have a more or less massive colordrift, we might look out for other possibilities.
And maybe we also should open a discussion which of these filters still are necessary today? Except for polarizers, I don't see much value of grading filters or medium stoppers, as all these long time exposures can also be done with software.