DIY Apodization Filter replace the aperture.

My first thread in the open talk forum.

https://www.dpreview.com/forums/thread/4247863

This is a simple process to make Apodization Filter.

It is installed inside the lens.

removed the aperture

set APD filter

It is working.

Looks interesting can you actually describe what you've done???

The illustrations without any materials/procedures etc isn't a great deal of help!

STUNNING!!!

petrochemist wrote:

Looks interesting can you actually describe what you've done???

The illustrations without any materials/procedures etc isn't a great deal of help!

The material can use the high quality polyester resin with black dye.

First, make the concave of translucent resin on the glass.

Second, you can put on other glass and use clear resin to finish it.

vfan wrote:

petrochemist wrote:

Looks interesting can you actually describe what you've done???

The illustrations without any materials/procedures etc isn't a great deal of help!

The material can use the high quality polyester resin with black dye.

First, make the concave of translucent resin on the glass.

Second, you can put on other glass and use clear resin to finish it.

Interesting way to make the apodization filter....

I wouldn't have expected that to be optically ok, but it seems fine and smoother tonally than simpler methods (e.g., laser printing on transparency material).

ProfHankD wrote:

Interesting way to make the apodization filter....

I wouldn't have expected that to be optically ok, but it seems fine and smoother tonally than simpler methods (e.g., laser printing on transparency material).

I had the laser printing version. It is bad optically of image.

vfan wrote:

ProfHankD wrote:

Interesting way to make the apodization filter....

I wouldn't have expected that to be optically ok, but it seems fine and smoother tonally than simpler methods (e.g., laser printing on transparency material).

I had the laser printing version. It is bad optically of image.

You're getting quite a bit worse for your lasered filter than I got for the laser-printed filter, but that's probably because I prefer to put the apodizing filter in front of the lens -- which means the area is larger and thus the laser dots are effectively smaller. I never got any of the obvious diffraction patterns you got, but I agree optical quality isn't very good.

Inkjet printing on transparency material gives better tonality than laser, but the transparency material is coated to accept the ink, and that coating acts as a bit of a diffuser. Laser-cut or programmable paper cutter "sink strainer" designs I made had very heavy textures in the bokeh. You can do quite a bit better exposing and processing B&W film to make the filter (I tried 6x6cm film), but it's a pain. I also built a homemade sputtering machine to coat filters with a controlled optical density gradient; it produced very good quality, but it was a nasty hack and hard to use (although I've often thought about making a better sputterer now -- the one I made was many years ago, before I had a 3D printer, etc., to make the parts).

Your approach seems to produce a filter very much like the original Minolta STF 135mm's apodizing filter. So, how easy was it to produce a controlled gradient? Any fabrication tricks? Any optical problems with the significant thickness of your filter?

BTW, the other trick one can use is a variant of what Minolta did in the Maxxum 7's STF (Smooth Trans Focus) simulation mode: vary the aperture during exposure. They actually did it as a multiple exposure with different aperture and exposure time settings to approximate the desired apodization function, and that obviously can also be done in post with just about any digital camera combining aperture-bracketed exposures. No filter needed, but you need to be able to automate aperture control... which isn't as easy with most manual lenses. It was easy for me to implement in-camera using Canon PowerShots under CHDK (although most current PowerShots don't have a controllable aperture).

I made B&W films of filter many year age.

Image quality is full of blur, ghosting and flares, and some highlights can also produce overlays. B&W film production also has a lot of uncertainty, it is difficult to control.

So I don't think film (or laser printing ) can get good applications in optics element.

In my approach, I can control the dye concentration to produce the desired gradient.

Polyester resin needs to be very uniform and degassed.

It does not reduce sharpness and produces diffraction, but it still adds flare.

In the Maxxum 7's STF method, it can't take pictures in daily. I did not consider this option.