305 G Claron into Copal 1

[Smitty]

Anyone know if a G Claron 305 barrel lens will screw directly into a Copal 1 shutter?

Steve

[Len Middleton]

Mine did.

[andreios]

There were many variations of clarons, so make sure before buying, lest you end up with an unmountable (but still very fine) lens - like mine 240mm G claron.. .

[Andrew]

there were two versions of 305 g-claron so it depends which one you have
the newer version goes straight into a Copal #1... it's the most common and it takes a 67mm filter
the older [dagor] version goes into a Compur #2 [as per 240mm convertible Symmar] and this one takes a 58mm filter

[Smitty]

If it is the late G Claron it should screw into any Copal 1 shutter without need for modification or machine work? Focus, alignment etc. will be ok? This is the 67mm filter size...

Steve

[Andrew]

If it is the late G Claron it should screw into any Copal 1 shutter without need for modification or machine work? Focus, alignment etc. will be ok? This is the 67mm filter size...
Steve
I think it's ok, a lot of people seem to swap barrel mounted g-clarons into shutters and I've never read there was a problem with the optics.
But you can't expect that the aperture scale will be correct unless the shutter came off another g-claron of the same focal length so you'd need to either make new scales or work out a correction factor.

[Cor]

I have done this for several G-Clarons.

What I do: I measure very carefully the total length of the G-Claron in it's barrel, and than when fitted in a shutter: the length should exactly be the same (and it thus-far does).

For the aperture scale: Put any lens with a verified aperture scale, focus on infinity, point to an evenly lit wall.

Place your spot meter on the ground-glass (preferably on a tripod), shield the spot meter from stray light, and take (EV) readings at each f stop.

Place the G-Claron on the camera at infinity, same wall, spot meter on the same position, move aperture to noted EV vales and mark these f stop on the blank shutter.

Good luck,

Cor

[Smitty]

I have a shutter on the way then will ship down to SK Grimes for engraving the aperture. Spoke with them on the phone, they also have done work for me in the past.

[Andrew]

I have a shutter on the way then will ship down to SK Grimes for engraving the aperture. Spoke with them on the phone, they also have done work for me in the past.
that'll cost you, but you'll know that it's been done correctly....
get them to CLA the shutter while it's there and you should have years of happy service from the claron

[Andrew]

I have done this for several G-Clarons.

What I do: I measure very carefully the total length of the G-Claron in it's barrel, and than when fitted in a shutter: the length should exactly be the same (and it thus-far does).

For the aperture scale: Put any lens with a verified aperture scale, focus on infinity, point to an evenly lit wall.

Place your spot meter on the ground-glass (preferably on a tripod), shield the spot meter from stray light, and take (EV) readings at each f stop.

Place the G-Claron on the camera at infinity, same wall, spot meter on the same position, move aperture to noted EV vales and mark these f stop on the blank shutter.

Good luck,

Cor

yes ! it seems to be the logical way to deal with checking apertures because it uses direct measurement of light transmission through the lens !

I've done this, except that I used open blue sky. maybe a wall would be better? I tried a number of unmolested lenses of different focal lengths to validate the technique and I got such close EV values that my guess is any idiot [like me!] could get an aperture scale correct to within 1/3 of an f-stop

my comment would be that it should work with an incident light meter, but you should standardise everything possible in the method so you'd point the camera at exactly the same area of wall/sky after you've focused for infinity, measure off the centre of the glass, and hold the meter hard against the ground glass.... and I did it under a dark cloth to reduce stray light