Canon EF 50/1.2L is one of the worst rated Canon L lenses in almost all web reviews that I have read, especially when it comes to the corner performance wide open.
Here are images with superimposed grid for better reading of distortion.
Final word: Lens Turbo II, while optically inferior to Speed Booster Ultra at wide open apertures, is actually not overall bad option.
Canon FD 50mm.4, lens Turbo II combination will cost no more than 250, if youre lucky 200.While Speed Booster Ultra has much better extreme corners than its predecessor, nearby zone just before extreme corners is slightly weaker.First test is boring ISO 12233 chart visual test, which however can tell us few useful things.We can also notice greenish corner cast on both Speed Boosters but also on Lens Turbo.First what I was curious to see was performance wide open.(Olympus Om to Canon EOS.g.) Metabones Speed Booster Original can be another valid option, if you can find it for a good price on the used market.Scene 1 focus distance just before infinity.This is most probably caused by combination of light fall off, and steep light ray angles, hitting sensor edges.That might sound like not a big deal, but resulting differences in FOV are surprisingly larger than numbers indicate.There is also a glare in high contrast situations when shooting towards light source.All three focal reducers penetration testing with backtrack pdf slightly increases barrel distortion, with Speed Booster I being most obvious.There is a noticeable vignetting on the short end at a fully open aperture.Neither of these adapters have any mount play and both fit snugly my Sony FS100.For example the total cost.Comparing three focal reducers, I would say that Speed Booster Ultra has slight edge, but nothing extremely significant like when wide open.The biggest difference between these adapters though is the price.
When it comes to CA, all three focal reducers kill me softly sarah cross pdf shows some, but that is to be expected, because EF 50/1.2L is under corrected in that regard (as many super fast lenses).
Sony A7 with Metabones Smart adapter III is overall most even performer across the frame, but we can also see that Speed Booster Ultra is close second and Lens Turbo II staying behind, mainly because of the glow wide open.There are other possible issues that might affect results, mainly mechanical mount tolerances and of course sample variations.Despite all my efforts to make lab test images relevant, there are too many variables that I cant control as Id like, one of them being sample variation and/or, mount tolerances.g.This is another strong point of the Speedbooster, which became popular with loads of camera guys switching from Canon 5Ds to something like Sony FS100/700.You can examine crops above, but IMO, Metabones Speed Booster Ultra is clearly superior in all zones.Changing lenses on the adapters and especially using ltii without aperture control, while trying to shoot real life images is simply too challenging and it might cause serious damage to my cameras.It might be the light reflected from the sensor and the rear surface of the Lens Turbo, which is flat.
That was expected, and might not be a big problem in real shooting.
Its not hard to see that you can buy similar equivalents 5 times cheaper, or have 5 times more glass for the same money.