Argus C-4 focus

[Brownie_Holiday]

Hi all. Looking for a method to check the focus on an Argus C-4. I've got it all cleaned up, the glass is in good shape and the shutter/diaphragm are working very well. The rangefinder is off, but I need to check focus before I start screwing with it.

I've read where people use everything from waxed paper to cellophane tape to mimic ground glass. I have a piece of frosted glass that works, but as of yet I can't seem to find a good 'field' method to complete the test. I was told to check it at 10' and 25', others say each end of the range. I've been successful in getting the image to project on the plane, but so far any target I've used is too small to see focus.

So, what should I use for a target? What distances are correct? What do I use to enlarge the image? Does a loupe work? I've tried a rather powerful magnifying glass, no luck.

Any help would be appreciated.

 

[Donald Qualls]

When I've done this (with scale focus, and when adjusting a Kalart on my Speed Graphic), I always started with ensuring the infinity focus was correct. Once that's verified or adjusted, you'll check closer distances. The good news is, on that Argus, you won't have to worry about adjusting the slope, as you would in a Kalart -- so if you get the infinity right, the rest should fall into line.

You still want to check the close and intermediate distances -- but they ought to be okay once the infinity is right.

 

[Brownie_Holiday]

When I've done this (with scale focus, and when adjusting a Kalart on my Speed Graphic), I always started with ensuring the infinity focus was correct. Once that's verified or adjusted, you'll check closer distances. The good news is, on that Argus, you won't have to worry about adjusting the slope, as you would in a Kalart -- so if you get the infinity right, the rest should fall into line.

You still want to check the close and intermediate distances -- but they ought to be okay once the infinity is right.

Ok, but how do I do that? How do I set it up so I can see the image on the glass? That seems to be the part that has me stumped. The image is so small on the glass I can't tell if it's in focus or not.

 

[Nicholas Lindan]

An easy, and quite often good enough, solution is to stretch some Scotch Magic tape across the inner film rails. Use a loupe magnifier to examine the image.

If you use infinity to calibrate the rangefinder then there isn't any need to examine the ground glass (ground tape?) image. Just use the furthest thing you can find and calibrate the system so the rangefinder says it's at infinity. The lens' infinity position is usually accurate.

Confirm by shooting film with the lens wide open at various distances. One test from the old days was to tape a newspaper page to the wall, mark a line down the middle of it and then take a picture at a 45 angle, focusing on the line. The result should be a sharp line with about equal amounts of in-focus print on either side of the line, i.e. that the rangefinder is centered on the line. You can do the same type of test with a line of chess pieces.

 

[Brownie_Holiday]

An easy, and quite often good enough, solution is to stretch some Scotch Magic tape across the inner film rails. Use a loupe magnifier to examine the image.

If you use infinity to calibrate the rangefinder then there isn't any need to examine the ground glass (ground tape?) image. Just find the furthest thing you can find and make calibrate the system so the rangefinder says it's at infinity. The lens' infinity position is usually accurate.

Confirm by shooting film with the lens wide open at various distances. One test from the old days was to tape a newspaper page to the wall, mark a line down the middle of it and then take a picture at a 45 angle, focusing on the line. The result should be a sharp line with about equal amounts of in-focus print on either side of the line, i.e. that the rangefinder is centered on the line. You can do the same type of test with a line of chess pieces.

I think a loupe is the right answer. I have the other parts of it solved, my only issue is seeing the image on the glass.

 

[Donald Qualls]

I think a loupe is the right answer.

Yep, unless you're as nearsighted as I am (I just take off my glasses and have the equivalent of an 8x loupe), you need magnification to check critical focus even on larger film than 35mm.

 

[Brownie_Holiday]

I had hoped my vintage ginourmous magnifying glass would do the trick, but it failed miserably!

 

[Donald Qualls]

Shorter focal length = more magnification. Bigger lens = brighter image, in some cases ability to use both eyes. Got a 35 mm SLR lens? Put the film side toward your subject and those are good for up to about 30 diameters. Even a 50mm is around 20x.

 

[gone]

Hi BH. Just set it to infinity and all the other distances should be fine. Be careful about getting the focus gears properly lined up if you decide to take it apart. It can be a real bear getting it properly aligned again (don't ask me how I know) unless you clearly mark them where they align. These are nice little cameras. Mine took surprisingly good photos, not sharp, but sharpish enough, and the shutter sound was fun. Like an old spring toy, which is basically what it is. Unfortunately, the cameras don't have strap lugs. I had mine in the bottom half of a Bessa R case when I bent over one day and the camera plopped out and landed upside down. It still worked, but the gravel it landed in gave it a decidedly odd appearance on the top.

 

[Brownie_Holiday]

Hi BH. Just set it to infinity and all the other distances should be fine. Be careful about getting the focus gears properly lined up if you decide to take it apart. It can be a real bear getting it properly aligned again (don't ask me how I know) unless you clearly mark them where they align. These are nice little cameras. Mine took surprisingly good photos, not sharp, but sharpish enough, and the shutter sound was fun. Like an old spring toy, which is basically what it is. Unfortunately, the cameras don't have strap lugs. I had mine in the bottom half of a Bessa R case when I bent over one day and the camera plopped out and landed upside down. It still worked, but the gravel it landed in gave it a decidedly odd appearance on the top.

Shouldn't need to mess with the gears. Fine focus is handled with three set screws between the aperture and focus rings. The rangefinder requires removal of the top and some adjustment of two screws, one for vertical and one for horizontal. I actually have a complete set of instructions, my only issue (well, at least so far) is determining if it's in focus at given distances.

If it turns out it's in focus based on the dial but the rangefinder is off, I could just use the dial and ignore the rangefinder. If it's not in focus then I'll have to deal with that first, no point in adjusting the rangefinder if the result is out of focus.

 

[Brownie_Holiday]

Ok, it looks like it's focusing just fine. I checked at 10', then 25', then infinity. All 3 look pretty doggone good. Ended up using cellophane tape. Not sure why, but the matte glass I have is so coarse all I could see in the loupe was the grain of the glass. BTW, if you want a cheap loupe, good old Harbor Freight sells a set of 5. I wasn't going to at first, then I figured what the heck. If they suck, I'm only out $4. Turns out they work better than expected.

Thanks all. Now I gotta' get up the guts to take the top off and mess with the rangefinder adjustments.

 

[Donald Qualls]

Now I gotta' get up the guts to take the top off and mess with the rangefinder adjustments.

Do you? Does the RF disagree with the scale, or with the actual lens focus?

 

[Brownie_Holiday]

The scale and focus agree, so I can use the scale to determine focus. The only thing off is the RF itself. So, no. I don't have to, but I would like to get it back to original.

 

[Donald Qualls]

That sounds like the gears could be off by one or more teeth. If so, give the C3 and C4 family have removable lenses, you may not need to remove the top cover at all.

 

[Brownie_Holiday]

It's off vertically as well. I think the alignment has simply moved over time, camera probably got bumped here and there. One of the guys from the Argus Collector's Group was kind enough to send me scans of the complete disassembly procedure, including a supplement for just the rangefinder.

 

[Donald Qualls]

Ah. Vertical needs fixing, for sure. Fix that first.