35mm adapter (Footage) Problems with a center of light in the middle

[Nicolas Gregoire]

Hello!

I'm just messing around trying to build something for cheap to try and see what an adapter can look like!

Here is my setup

But I have a problem in the center of my image! There is a round of light in the center and I don't know how to fix this?

http://www.vimeo.com/1086624

I tried to use another lens and it does the same thing, the round is sometimes smaller. Like if I close the iris it becomes smaller but I also lose a looooot of light in my image!

Please help if you know what to do ;0)
Thanks!

 

[mvansomeren]

I think the problem is that your "focusing Screen" doesn't defuse the light well enough so you get a hot spot.

 

[AwakenedFilms]

Maybe you need to add a beer can to tighten up the design?