Hi all,

I am currently in the process of building a 5x4 camera and my own lens, everything is going well except I will be in need of a shutter, due to the f number on the lenses I am building even ISO 3 paper negatives would need to still have quite a fast shutter speed.

I am ok in some instances to stop the lens down to say f11 or a smaller aperture for landscapes, however I am also thinking of using the camera for portraits as well so would shoot fairly wide open which is where the issue comes.

I am unable to source/afford a shutter that is big enough for some of the lenses I am designing so I will need to make my own, I would need it to be very simple to make - I am thinking about something like a spring loaded guillotine or rotary disk with a slot cut in it.

I am thinking that if I can produce something with a fixed speed then I could simple stop the lens down slightly or use ND filters on the lens to make sure that its properly exposed - I would want to shoot quite wide open for the shallow DoF on portraits.

Is there a simple design I can use to produce a shutter? I was thinking about making a double iris/clapperboard shutter of my own design which would allow for variable speeds, however I would want to go with something simpler.

Could I produce something simple like a spring loaded flap infront of the lens something like:

Spring loaded flap in front of lens with small arm sticking out of shutter assembly
A dark slide infront of the lens and infront of the shutter
Open the spring loaded flap to put it under tension
Let the dark slide fall and also release the spring loaded flap
The gap between the falling slide and time take to flap closed would equal the shutter speed
The flap would be sprung to flip downwards to counteract the fact that the slide exposes the top of the negative first.

Can I have some other simple ideas for shutters that can be made, the design would need to be scaled up or down depending on the lens I would be shooting.