What have I done this time?

[tonyowen]

Are you setting the F16 or F22 on the shutter or the lens? Are your GG images at max aperture?

The shutter - apertures determined by measurement of 'apparent diameter'. The gg images were at the full f5.6 aperture.

regards

Tony

[Dan Fromm]

The shutter - apertures determined by measurement of 'apparent diameter'. The gg images were at the full f5.6 aperture.

regards

Tony

Wrong. When a barrel lens is in front of or behind a shutter, set the shutter's diaphragm wide open and use the barrel's diaphragm to control depth-of-field and (partially, shutter speed matters too) exposure.

[cowanw]

I would imagine that closing the shutter out front of the lens would cause vignetting; there are purpose made tools for that from years back in various shapes, such as Hi tech filter holders but they are so old I cant find any on the internet. As Dan implies the shutter f stop will not alter DOF as expected.

[Cor]

If I understand your lens set up correctly: after you close your shutter, some light can still enter your lens, thus causing weird effects. Only when you push in your darkslide no more light can hit the paper.

best,

Cor

[tonyowen]

If I understand your lens set up correctly: after you close your shutter, some light can still enter your lens, thus causing weird effects. Only when you push in your darkslide no more light can hit the paper. best, Cor

correct, the top and bottom of my 'holder' would allows some light to hit a portion of the extreme edge of the lens' shape. I'm surprised at the magnitude of this 'contamination'.

I can easily cover those spaces and see what happens.

regards
Tony

[Dan Fromm]

Ah! So what looks like a gap is a gap. Unwise.

Tony, you need to minimize the distance between the lens and the shutter.