Hi All,

I found three supplemental lens made by kodak labeled Portra Lens 1+, 2+, and 3+, they are designed as close-up lens.

The instructions say that when used with a camera that can do ground glass focusing, it makes possible wide-angle effects.

Has anyone used these in this way before???

Also, I have tried to estimate the adjusted focal length, by measuring the lens to film plane distance in inches (when focused @ infinity) and then converted them to mm's. Is this a viable way to estimate the focal lengths for each lens??

Any help will be greatly appreciated!!

Thanks

David

By the way, I've put them on my 101mm Optar and they appear to widen the field of view but I don't know what they are doing to my resolution.

D.

Actually they are spreading the image out over a larger area, but since your film size stayed the same you are getting a close up view of the center of the 'wider area, so in effect these act to make the lens longer, not shorter. Hence the term portra.

And yes you do know what's happening to your resolution, and it ain't pretty. Well acutally its a nice effect for portraits.

Les hit it on the head. I've been using a Portra #1 and #2 for a while now. They do decrease the resolution, but in a pleasing way for taste. You can find information about them in the old Kodak field guides.
They also made a Telek series which I've also used with interesting results. Just make sure you've got enough bellows to use these babies though.
Have fun!