Nikon 50mm f1.4 and Tokina 11-16 f2.8 with Mitakon lens booster

It was really bright this afternoon so I decided to see if I could replicate the “blue spot” that has been reported using this Mitakon lens adaptor. On a very bright brick wall at f1.4 it was quite apparent but I didn’t realize it until I uploaded the images to review. It isn’t in other images at f4 and above. A little tricky to use but I enjoyed myself! The only issue is what to shoot at approx. 71mm. So here are a few images from earlier today including a crop to show the moon.

You can see the blue dot clearly at 11mm in the bottom two images taken with the Tokina, especially in the crop… It appears that, for the Tokina, when the lens is wide open there is no blue dot. In the 50mm, the opposite is true! When I stop down the aperture, the dot disappears!

I did, however, open the lens up manually (the adapter doesn’t have aperture control) but that works fine. I will re-test this in the sunlight and revisit this issue since I really want to use this lens and adapter for architecture while travelling.