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Add aperture blades to old manual lenses

Started Aug 31, 2018 | Discussions thread
petrochemist Veteran Member • Posts: 3,619
Re: Waterhouse stops and Apodizers

ProfHankD wrote:

petrochemist wrote:

I've used paper discs up against the front element (with both circular & shaped apertures) and have tried an iris in front of the lens. In a few cases I've ended up with noticeable vignetting (usually when the lens has a long built in hood) but many have been OK.

Vignetting happens if your opening is too large. I know that's counter-intuitive, but it's how optics work. You're then vignetting rays from the lens aperture, which is placed differently, and that explains why the front element is bigger than focal_length/f_number.

I know that's one of the causes but wasn't the case here. The lens I was using for my last experiments was a 50mm/1.2

None of the apertures I used were even remotely close to the limiting size for this lens, typically being around 1/2" in their biggest dimension. For ease of use I was just applying the masks at the end of it's hood about 1.5" from the front element.

A slot in the hood to allow easy inserting of masks & waterhouse stops is something I'm considering...

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