Optimal aperture position?

Started 2 months ago | Discussions thread
fferreres Veteran Member • Posts: 3,748
Re: Apodizing filters

ProfHankD wrote:

fferreres wrote:

ProfHankD wrote:

fferreres wrote:

I really like it. Taking for example a 50/1.4, if I measure the diameter of the aperture, and of the barrel, would you be able to print one on transparent material? I am just asking because many lenses are easy to open and install one? The apodized bokeh even if stopped to f2.8 has a lovely look.

You can easily get overhead transparency material designed for either inkjet or laser printers. The inkjet stuff looks really hazy because it has a rough coating to absorb the ink. The laser material is more transparent, and will not melt when it contacts the binding drum in the laser (don't try using inkjet transparencies in a laser!).

The catch is that sizing it correctly involves determining the widest aperture at which the lens doesn't vignette, which is very lens dependent.

This is a very good idea. I didn't see it mentioned anywhere. Any suggestion at what shape to print assuming laser?

You'd print something like the image I showed above:

The above is 6000x6000 pixels with a central shaded portion that's a tad less than 2200 pixel diameter. If you printed that 6000x6000 image scaled to 60mm wide, then the central shaded area would be about 22mm -- or about f/2.3, which might be small enough to not suffer too much vignetting.

I've done this many times, but don't happen to have images handy right now.

BTW, I've also tried producing apodizing masks using film and using a homemade sputtering machine... each of which works better than this, but is much harder to do.

Fantastic. I have bookmarked the thread.

If there was anything that could print into a skylight filter. There are so many sizes and it's so easy to remove the element.

Thanks Alan too for the links. I would need a laser printer first (some are very cheap) so it am only toying. Those are some expensive optics!

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