Although there is far more to a lens than shooting resolution charts, these tests are helpful for looking at certain performance characteristics. I charts below are from four spherical 50mm lenses, shot first clean and then with lens flare. The flare was provided by a fairly aggressive Dedo spot-light hitting the lens from the left of the chart.

All lenses were first shot wide open, and then again when stopped down to T2.8

Luma Tech Illumina Mk2 50mm T1.3

Luma Tech Illumina Mk2 50mm T2.8

Cooke S4 50mm T2

Cooke S4 50mm T2.8

Arri/Zeiss Ultra Prime 50mm T1.9 

Arri/Zeiss Ultra Prime 50mm T2.8

Zeiss Super Speed Mk3 50mm T1.3

Zeiss Super Speed Mk3 50mm T2.8

I was surprised by the noticeable difference in sharpness and contrast between the two T1.3 lenses. The Super Speed was far softer than the Illumina wide open. Perhaps one might expect this in lenses built 30 years apart, but the lack of resolution was striking. The Super Speed's contrast 'smearing' wide open (particularly evident in the far left of the grey scale (0.2 grey) was a bit more alarming.

The resolution impact of the lens flare was most evident in the Illumina, whilst the Ultra Prime fared best under the flare. I have always liked the Ultra Primes' contrast performance under flares... and unlike the un-flareable Master Primes the UP do still flare dramatically whilst retaining contrast. Although I have used the Illuminas for spectacular lens flares, its always at a heavy cost to the rest of the picture.

Although the Cooke S4 and the UP do not reach to T1.3, by time all of the lenses were stopped down to T2.8 you do begin to see why these two are the more premium choices. At T2.8 the UP and Cooke out-perform the faster lenses. 

Both the UP and S4 also deliver a far more 'useable' image wide open than the Super Speed. Albeit at a slower stop, they deliver a far more acceptable photographic result.

The Illumina fares better at T1.3 than the Super Speed, but then the addition of the flare is most noticeable in the Russian glass which seems to have almost no flare suppression.

Overall, for the purposes of this test, I would say the Ultra Prime 50mm fared the best. Given that I would need to stop down a half stop on the Super Speeds to get a more useable lens, it would always be preferable to shoot wide open on an Ultra Prime.