Argus C3 shutter test

I've been cleaning up a C3 and have been pleased with the results so far. Once I got the lens unfrozen the focus seems ok (although the rangefinder images are good horizontally but not vertically, or maybe vice versa -- I'd like to look through a C3 that works properly at some point to see what I'm shooting for).

The shutter works, but didn't sound accurate. I shot a test roll and got the results below. I'm using a sampled K-value in Photoshop (51x51 pixels on pavement that should be a decent midtone) to measure density. I think the results are telling me that the shutter tensioning doesn't "kick in" at all until the lower speeds. In other words, the speeds aren't just off, they aren't varied much at all until you get to 1/20th or below).

If that's right, is the best best approach to try repositioning the entire shutter tensioning apparatus to the right so that it starts off with more tension on the heavy wire that links to the shutter control mechanism on the right? Are should I go ahead and resign myself to removing/cleaning the entire mechanism?

I guess I'm asking if these results suggest a shutter that needs adjusting, or overhaul? At my skill level, there's a chance that one I take it out I'll never get it back in.

Thanks.

Meter Target of scene:
f/8 1/50th

Results

f/8 1/300th -- K-value: 71%
f/8 1/200th -- K-value: 71%
f/8 1/100th -- K-value: 72%
f/8 1/50th -- K-value: 73%
f/8 1/30th -- K-value: 68%
f/8 1/20th -- K-value: 55%
f/8 1/10th -- K-value: 10%

f/4 1/300th -- K-value: 49%
f/4 1/200th -- K-value: 49%
f/4 1/100th -- K-value: 43%
f/4 1/50th -- K-value: 44%
f/4 1/30th -- K-value: 39%
f/4 1/20th -- K-value: 33%
f/4 1/10th -- K-value: 6%

(note: it was evening and the light was fading, so I'm assuming the meter value had dropped a stop or so for the second set)

I've not tested mine (having a preference for blissful ignorance ) but there was a recent discussion about C3 shutters on the Argus Collector Group Yahoo site that included a comment from a guy who has worked on quite a few:

The ACG website has some instruction and repair manuals for the C3, not sure if there is anything useful there or not. My own impression has been the mid-range speeds can be made fairly accurate, but the highest is almost always an optimistic marking, a trait not uncommon to mechanical shutters in other brands. And judging by the sound, the lowest speed relies on some extra-duty mechanism which could likely show effects of being dirty.

That's my 1.3 (after tax) cents.

I bought a C3 about 11 year ago. I checked it out and it seems to work. Didn't check the shutter before I disassembled it and I never put it back together. I think I still have all the parts in a box.

DWThomas said:

I've not tested mine (having a preference for blissful ignorance ) but there was a recent discussion about C3 shutters on the Argus Collector Group Yahoo site that included a comment from a guy who has worked on quite a few:

"However, I would never call the C3 "accurate" or "precision." The nature of the shutter mechanisms just does not lend itself to precision. Even after cleaning, repair, adjustment, most will not achieve a shutter speed of faster than about 1/200 despite the markings on the dial. And although those markings suggest a range of shutter speeds, it is at best a suggestion. How do you adjust them? Clean parts helps. Other than that, the only factory adjustment is that little triangular lever inside down below the speed dial sometimes referred to as a "bell crank." The adjustment is awkward, primitive, and problematic. And getting the camera to show a clear difference between 300, 200, and 100 does not always happen. And the way the shutter blades open and close slowly and progressively challenges conventional ideas of "shutter speed."​

The ACG website has some instruction and repair manuals for the C3, not sure if there is anything useful there or not. My own impression has been the mid-range speeds can be made fairly accurate, but the highest is almost always an optimistic marking, a trait not uncommon to mechanical shutters in other brands. And judging by the sound, the lowest speed relies on some extra-duty mechanism which could likely show effects of being dirty.

That's my 1.3 (after tax) cents.

Click to expand...

Thanks for the info. I'd definitely settle for two or three speeds that were scattered somewhere around the dial.