Copal 3 equivalent with round diaphragm

[Larry Gebhardt]

I've got a 210mm Macro Sironar N which is in a Copal 3 shutter. Given that it's a macro lens I frequently have significant areas of the photo out of focus. If there are highlights in the out of focus area they are rendered in the shape of the aperture, which I find unappealing. I'm wondering if there's an easy shutter replacement that would have a round diaphragm. Ideally it will be a shutter, but I guess a barrel would also be a workable solution in many of my shots.

[Oren Grad]

One of my lenses is in a very early Copal 3 with a non-linear aperture scale and a ten-bladed iris instead of the seven-bladed iris that you see in later Copal 3's. Still a polygon, but subjectively a lot closer to round through much of its adjustment range. Perhaps it would be a direct swap, too.

[Richard Johnson]

Otherwise I doubt there is a solution other than using the lens wide open or making and rigging custom Waterhouse-style stops. Or using an old Acme or Ilex.

[Phil Hudson]

You might get a rounder aperture from a Compur 3.....

[Larry Gebhardt]

Looking at some pictures of the older Copal 3 the diaphragm does look closer to round. Probably would be close enough for my taste. The only Compur 3 shutter I see on ebay looks like what I had in mind. I'll keep an eye out for a bargain on one.

[domaz]

You could have the lens remounted into a Compound, but that would be very expensive.

[EdSawyer]

Compound or compur 3 both have more blades. Compound > compur > copal > Prontor (5! and straight!)

[Larry Gebhardt]

The compound looks perfect. I never knew these existed until now.

[koh303]

I had and sold a telexenar in a compound size 3, with a zillion blades, and a near circular opening.
Was a pretty thing. Those lenses are not expensive if you can find them, and the shutters are not that bad (though not great either).

[domaz]

I had and sold a telexenar in a compound size 3, with a zillion blades, and a near circular opening.
Was a pretty thing. Those lenses are not expensive if you can find them, and the shutters are not that bad (though not great either).

Compounds are reliable although I have my doubts that their air cylinder mechanism will be accurate when I'm high up in the mountains. Maybe not a good shutter for people living in Denver.

[koh303]

the compnound shutters are reliable, that is, they work when you press the shutter release - however, that says nothing about how fast that shutter will be, mountains or no mountains, and how close one exposure will be to the next. The air cylinder system is not ideal, but the aperture blades are great!