making a soft edge filter

[jlamarca]

I'm looking for a filter (or how to make a filter) that is significantly softer at the edges/corners than in the center. My Nokton lens has some sharpness falloff, but I want to create a mood that requires significantly more soft focus in the corners, and is not so tack sharp as the Nokton in the center either.

I know of the lensbaby, but this is taking the effect to the ridiculous/gimmicky extreme. Softening filters for portraiture seem to be pretty uniformly soft across the glass. I tried petroleum jelly around the edges of a UV filter but this creates strong flare much more so than soft focus at the edges.

Any suggestions?

 

[Matthew Allen]

Something like this? Or is that not sharp enough in the centre? Maybe you could achieve a similar effect by reversing an element in a lens. You could pick up a beater FSU lens to experiment with for pennies.

Another option would be a Holga or another medium format camera. With MF, even crappy lenses often appear quite sharp in the centre but show considerable softness towards the edges.

Matthew

 

[jlamarca]

Yeah I have a holga, and I like the falloff, but the vignetting can be pretty severe, and I don't really like shooting with it - so slow to wind and reload, and 120 is really expensive to shoot when you have a fixed aperture/shutter.

This lens pic you linked to - yeah it's too soft in the center at 2.5. Better at 5.6 but I can't tell what the corners look like with the all white background.

 

[Sonnar Brian]

Here are some shots with a Ziess Sonnar that had the rear module in backwards. before and after pictures after finding and correcting the error.

http://www.rangefinderforum.com/forums/showthread.php?t=57623

The Canon 50/1.8 would be a good candidate for reversing the rear element for a soft-edge effect. Just enough asymmetry to knock the edges out.