DIY Apodization Filter

[stingOM]

http://www.4photos.de/camera-diy/Apodization-Filter.html

[Lloydy]

Interesting, the Helios swirls have gone.

I love Markus Keinath's site, one day I'll get to the bottom of his incredible links page.
http://www.4photos.de/camera-diy/index-en.html


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[CBokeh]

Pretty sure this was written by mflenses member Zone V...

[CuriousOne]

I have also done it, but a bit different way - used laser printer with 1200DPI resolution, and transparency for laser printer, where I've printed different versions of such rings, with different falloff algorithms. Worked quite nice. Used it on damaged Chinon 50/1.7, where I placed it instead of aperture leafs.

[ZoneV]

Yes, it is my homepage.

CuriousOne, how was the quality of the transparent laser printer foil quality inside the lens? A lot of transparent materials are quite bad when inside the lens - much stray light for example.
I still have to try the laser printer way, would be fast, cheap and even large diameter would be possible. With slide film it is even hard to get type 120 film recorded.

[CuriousOne]

Quality was so-so, but I believe, this is due the fact that laser printer printout is not properly black, it is glossy and reflects back much of light. Of course, transparency material matters too, the best quality was obtained, I don't remember the brand but it was named "crystal clear transparency sheets" or something like that. Also note, when printed on transparent media, black toner is not that black, I'd rate uniform black print as ND8, not more. There are also transparencies for inkjet printers, and inkjets can provide dense, non-glossy black, but I never see fully transparent inkjet transparency, they are sort of matte. When looked under microscope, you can see that inkjet transparency has many pores, I think it is for ink to stick in. Such transparency by itself, provides quite interesting effects - of course it kills contrast, but adds rainbow axial CA.

[ZoneV]

Thank you, this was my fear.
Reflective film is bad, ND8 equals about a optical density 0.9, which is bad. Normal slide film has roughly about OD 2, which is not really good. Blurred bright reflections from the sun for example are still with hard edges. But to get these apodized is probably too much The Sony STF 135/2.8 and Fujinon 56mm/1.2 APD have no infinite optical density too.

Some films have quite good quality for this. Color Slide film has the problem that black is not black but color, at least at the few film recordings I got.

[CuriousOne]

There is another method, which should provide much better result, but harder to do in practice:

De-greased flat optical glass is taken, and small drop of black pigment placed in center. Even smaller drop of surfactant is placed in center of that black drop. Everything is allowed to dry in dust-free setting. In theory, this should provide us with what we need.

[ZoneV]

I suppose this will result not in a graduate filter, but a hard border between black and transparent. Furthermore thick glass is not good for putting inside a lens. Thin foils are much better.

[CuriousOne]

It depends on both liquid viscosity and surfactant concentration. Back in chemistry class, we were doing chromatography, and shape was quite similar to one we need.

[ZoneV]

[Lloydy]