Making aperture masks for camera lenses.

[ollypenrice]

Since Steve Richards (that dependable chap!) tells me they work, I made an aperture mask for my Canon lens to avoid using the diaphragm. I used thin plastic sheet for the circular mask and draft excluder self adhesive foam strip to hold it inside the lens hood. No permanent fixings involved.

The compass cutter was recommended by Psychobilly and found on the net here in France. (I downloaded it via the Post Office...)

Matt black to finish, of course.

My calculations suggest that this should give me about F3.5 which I know the lens can handle. We'll have to see!

The idea is to avoid diffraction effects and not have to put the lens in a DSLR first to set the aperture. Snatching it out while connected does no harm but isn't nice and I don't want multi spikes because I want to combine lens colour with scope luminance.

Olly

[Psychobilly]

Looks like a neat soultion... I like the foam to give an easy light tight seal in the lens hood...

I will be interested in the results...

I still haven't properly tested the new "L" Glass on astro targets yet.. but I know the Vixen ED81S would benefit from an aperture mask to get rid of the artefact's from the lens spacers...

Peter...