Lowering ASA of BW Film

[mrred]

Would it not be easier (and cheaper) to make a diaphram? A fixed one anyway. The F number should be straight forward math, I believe it's the ratio between the focal length and the diameter of the aperture of the lens. (http://www.uscoles.com/fstop.htm) You are making a camera, you can drill a hole. This will insure detail on the image, predictable results on the film and a whole lot less screwing around.

Just a thought........

 

[Mustafa Umut Sarac]

mrred ,

I know Weston and Adams did what you suggested but f:1.5 Ektar is famous for its bokeh and as Ian Grant warned it is only corrected for green and this blurs the not focused area even more.
I love these qualities and want to protect it , if I can not do this , I would not use that lens as a ultra sharp f:64 lens because it doesnt qualify also.

Look at Ian's link at the post. And hole or slit discusses lot at large format forum and they add abberations. I love some lenses as they are designed for .

Thanks ,
Umut

 

[mrred]

That makes sense.

 

[Rudeofus]

Just a suggestion for a really low cost ND filter: what about underexposed slide film? Take a few pictures of a gray surface with varying exposure and develop normally. This should give you a range of ND filters which cover up to 6cm diameter if you use 120 roll film.