Changing Speeeds On Cocked Shutter

[shutterfinger]

Yes, I had a supermatic that the 1/2 or 1/10 was off on after getting the rest of the speeds from 1/100 and slower in. I had slightly over filed the position so I used a Weller 8200N and put a little silver solder on the segment and redressed with a file. More than a few thousands may flake off. Adding brass with a brazing rod and torch might work also if one works quickly. The major problem is the dial distorting from the high heat of a soldering gun/iron or torch.

As for speeds above 1/100~1/125 they are controlled by the booster spring(s). I have tried reforming the ends of the booster spring so that it would compress more with no significant effect on the speeds. I have yet to make a new spring to see if that gets the speed up to par.

As for the speed tester I use which is similar to yours I have found it inaccurate above 1/250 second shutter speed. I have taken some known good shutters and made equivalent exposures at several speeds in addition to the fast speeds in question with an 8x10 gray card evenly lit from about 10-15 feet in the center of the frame on ISO 400 B&W film. The gray card had the same density/tone throughout set of exposures, all film processed in the same daylight tank at the same time, scanned at the same manual settings and if read with a densitometer would be within a .1 unit of one another. The tester showed the speeds to be 1/2 stop slow at 1/250 to 1 stop slow at 1/1000. I have tested other shutters that tested 1 stop slow at 1/200 and 2 stops slow at 1/400 to have exposures on ISO 400 film to be significantly over exposed at those speeds.

 

[Tom1956]

I am convinced that on this Graphex-X I've been working on is suffering from a completely different problem than the cam that I actually addressed. As I was rebuilding the shutter I noticed upon inspection that the bushing in the main lever assembly was scored, and that the post it turns on was worn down and scored. The best analogy would be "ring ridge" in a worn gasoline engine. Because of this wear, the main lever assembly is allowed to "cock", or bind under the intense spring pressure. This binding of course, causing slowed shutter speed. So in essence, I only addressed the problem and not the cause. But even if I had the tools and resources to fabricate a new main lever bushing, it would be of little good because the post it rides on would still be worn and uneven. There comes a time when a device is so worn out that repairs are to be considered temporary. This worn condition explains in my mind why achieving the 400 speed would be impossible. By then, the booster spring, along with the regular 2 other springs causes such a bind that it's a wonder it could move at all.
All in all, a temporary repair, but at age 56, anything is temporary to me. I , myself, am getting more temporary quick.

 

[Ian Grant]

Is it off topic to ask if this holds true for TLRs? I'm talking specifically about mine (of course), which has a Compur shutter.

It's exactly the same, you can adjust the speed before or after cocking, except for some Compur (and similar) shutters 35mm, folding 120's (and 127's), TLR, Large format.

 

[pstake]

It's exactly the same, you can adjust the speed before or after cocking, except for some Compur (and similar) shutters 35mm, folding 120's (and 127's), TLR, Large format.

I do not understand this comment ... should I or should I not adjust the shutter speed after cocking the shutter?

It's a prewar Ikoflex with a Compur shutter.

 

[Ian Grant]

I do not understand this comment ... should I or should I not adjust the shutter speed after cocking the shutter?

It's a prewar Ikoflex with a Compur shutter.

It's a rimset Compur you can adjust the speeds after cocking, the exception is the Compur Rapid with the extra spring for the high speed you can't move up or down from the top setting while the shutter's cocked.

Ian

 

[Vaughn]

I thought you used a derby.

Actually, for the lenses on my 11x14 I use a Kodak Polycontrast Filter Kit box. My hat of choice lately is an old felt fedora -- but it has a hole in it (other than where I stick my head in), so I need to tape up the hole if I want to use it for a shutter!

 

[pstake]

It's a rimset Compur you can adjust the speeds after cocking, the exception is the Compur Rapid with the extra spring for the high speed you can't move up or down from the top setting while the shutter's cocked.

Ian

Thank you, Ian. Very good to know!

My Karat 36 has the Compur Rapid and I'm familiar with the folly of going to/from 1/500 once the shutter is tensioned.

 

[Ian Grant]

Actually, for the lenses on my 11x14 I use a Kodak Polycontrast Filter Kit box. My hat of choice lately is an old felt fedora -- but it has a hole in it (other than where I stick my head in), so I need to tape up the hole if I want to use it for a shutter!

Get a decent shutter, maybe not . . . . . . . . . . . . let me buy them all first

The bigger Thornton Pickard roller-blind shutters don't turn up very often but when they do they tend to sell for slightly higher prices (if accurately described). They are very practical 1/15th to 1/90th + T, not all have speed indicators though. I have a few larger ones and have fitted some to the front of large Petztvals for others.. There's two types, front mounted and between lens and camera (just the way the casing's made).

Ian