12-10-2010, 11:25 AM
[quote name='popo' timestamp='1291969945' post='4920']
The other thread on the rear positioning of an external aperture reminded me of an idea I wanted to try but never got around to.
That is, would it be possible to convert a lens to give a Sony STF type bokeh by adding a similar front filter? For those who might not be familiar with the STF, it has an additional different "aperture" which isn't hard, but like an gradual ND filter getting stronger as you go outwards. This makes out of focus points appear as a smoother blur rather than a disk.
I've played about with shaped bokeh before. That is adding a physical mask in front of the lens. The bokeh then takes the shape of this mask with the in focus image looking normal. Would this also work to create a STF like response? For example, if I try printing an approximation of a suitable ND filter on transparency and cutting it to fit the front of a lens. Note I'm looking at proof of concept here and don't expect perfection. I just need the bits to try it out...
[/quote]
Well, first of all thank you for letting me see such kind of a one-of-a-kind bokeh oriented design. But it seems that the design of this lens (Sony STF 135mm) includes a special glass element which produces the ND filter effect gradually. And both the stepless and normal aperture sit infront of it. I mean, your design would be a real challenge...
Regards,
Serkan
The other thread on the rear positioning of an external aperture reminded me of an idea I wanted to try but never got around to.
That is, would it be possible to convert a lens to give a Sony STF type bokeh by adding a similar front filter? For those who might not be familiar with the STF, it has an additional different "aperture" which isn't hard, but like an gradual ND filter getting stronger as you go outwards. This makes out of focus points appear as a smoother blur rather than a disk.
I've played about with shaped bokeh before. That is adding a physical mask in front of the lens. The bokeh then takes the shape of this mask with the in focus image looking normal. Would this also work to create a STF like response? For example, if I try printing an approximation of a suitable ND filter on transparency and cutting it to fit the front of a lens. Note I'm looking at proof of concept here and don't expect perfection. I just need the bits to try it out...
[/quote]
Well, first of all thank you for letting me see such kind of a one-of-a-kind bokeh oriented design. But it seems that the design of this lens (Sony STF 135mm) includes a special glass element which produces the ND filter effect gradually. And both the stepless and normal aperture sit infront of it. I mean, your design would be a real challenge...
Regards,
Serkan