Fresnell Focal with Condesnor

[ELiTeHaYDeN]

If you are using a condensor should the fresnell be 220mm away from the Condenser or still 220mm from the lamp arc? im assuming the latter?

I seem to suffering from dim corners and I cant work out why.

 

[Moose]

No it wont. For the fresnel lens to "see" the arc at its focal length, the arc needs to be just slightly closer than the focal length of the fresnel. The amount difference depends on the focal length of the condensor and the bulb-condensor difference.