Yashica 124 repair guidance.

O.K., as per my other post I have narrowed the problem down to a

possible focus issue. When I focus at known distances, measured,

things are not in focus on the screen. When focused at infinity on a

distant object (100+ feet) , that object isn't in focus on the

screen, when brought into focus the dial reads 7-8 feet.

 

I would love to fix this myself simply for bragging rights, but I

know my limitations. Does anyone know how to adjust the focus on this

camera or a website that can point me in the right direction? If all

else fails I'll take it to the shop but I'd like to weigh my options

first.

 

thanks,

Todd

You mean that the readout on the knob does not coincide with infinity? Are there set screws for adjusting the knob position like on a Rollei? If the two lenses are tracking properly and you photos are coming out sharp at infinity, 3m, 1m (by using screen) then this should be all that is reqd. Sometimes the knobs are forced and slip from their proper position.

I think YashicaMat focus knobs are set on a "D" shaped shaft so the knob won't slip on the shaft.

 

You really need to take a couple more test shots before you start taking things apart. Find a flat, textured surface. A brick wall actually works well. Position yourself and the camera a measured distance from the wall, like 10 or 15 feet. Take one shot of the wall after focusing with the ground glass screen. Then take a second shot with the focus knob set at the measured distance, ignoring how much out of focus the image on the focusing screen may be. Then compare the two.

 

If you find the photo which was made by setting the focusing distance by scale is in focus on the negative, then it means the problem is with the viewing lens, the mirror or the focusing screen. If this screen is mounted upside down or the mirror is misplaced, or the viewing lens is mismounted this will cause the image on the screen to be at a different focus than the one hitting the film through the taking lens.

First thing to verify is whether the focus at the film plane agrees with that on the viewing screen. If so, you just need to adjust the scale. If not, you need to adjust the viewing lens, and *then*, if necessary the scale.

Your shots in your previous post look fine IF what you focused on is what is in focus in the photos. Other things in the photos can be expected to be out of focus considering the f4 aperture. I usually use the spot in the center to focus with the magnifier.

 

If you focus on the screen for something at infinity, and the focus knob is at the limit of it's clockwise rotation (regardless of the reading on the knob) when the screen is in focus, then the camera is probably ok. You just need to adjust the focus knob to the infinity stop. See pic and next post.<div></div>

Just for reference, the standard at min focus.<div></div>

And now, what to do about it...

 

To adjust it, set the knob to the limit of it's clockwise rotation. Remove the black cap that is shown in the pic. Beneath it you will find a nut. None of the Yashica TLRs I have worked on have a D shaped shaft, and the knob will spin on the shaft if you force it. The shaft is round so you can set the infinity focus to the knob index. Remove the black cap, hold the focus knob tightly and loosen the nut that lies beneath the cap. Be sure the focus at the lens standard doesn't move as you loosen the nut. Back it off about one full turn so you can rotate the knob freely without changing the focus. Now rotate the knob to inf, where it should come up against it's stop, and tighten the nut. That's it.

 

If you focus at inf using the screen, and ignore the distance scale, and your photos are in focus at inf, the above procedure should solve your problem. However, if using the screen to focus produces out of focus photos, you have another problem, which is not to difficult to fix, but involves some disassembly. Write back if that is the case, and we'll try to get you sorted out.<div></div>

An additional note here: Don't take the focus knob nut all the way off, and don't push on the shaft that it threads on to. The focus is actuated by four snail shell shaped spiral brass drivers, (two on each side of the camera). If you put pressure on the shaft, as if pushing it to the opposite side of the camera, the sprial driving plates can come off the detent notch on the shaft. Then it's major disassembly time. Don't ask me how I know. :)

Dean's notes are excellant, but I found a discrepancies from his comments during my re-build.

 

The front cover was not tight to the camera when the taking lens was actually focused to infinity. A very small gap measured at .010 inches was present on my unit. This gap should be consistant all around it's perimeter. Focus was set to infinity using a ground glass at the film plane with an 8x loupe while adjusting the focusing knob. When adjusted to the zero gap the taking lens was slightly out.

 

With the taking lens set to infinity per above, the adjusting knob can be set against it's travel stop and the lock nut tightened.

 

The tracking of the viewing lens can be checked using the loupe on the focusing screen.

As Barry says, find or make a ground glass so you can put it at the film gate and see what the taking lens sees. You can use frosted tape on a piece of glass or plexi, or grind a piece of glass with fine abrasive. Step 1 is to be sure the taking and viewing lenses have focus agreement. The knob adjustment is secondary to that, since if the taking and viewing focus is off, nothing will ever be focused where you think it is.

You can set infinity much more accurately if you use the method Mike Elek posted in his article on collimating a lens with an SLR.

 

Then, check the status of infinity in the viewfinder without moving the knob. You may have to adjust the mirror, screen or viewing lens which is normally on a helican that you can adjust. Sorry, I can't give specifics as I haven't worked on a Yashica TLR.

Regarding Barry's comments, there is a small gap between the facia plate and the camera body in the pic I posted, but it's hard to see. It has nothing to do with the focus though. I needed to give Todd a reference is all. The plate mentioned can actually be removed completly and the focus will not be affected. It mainly acts as a light baffle, and a place to mount the shutter button.

 

The thing here is, if Todds camera makes sharp photos when the ground glass shows focus at infinity, there is no need to check the focus at the film plane at all. The focus knob just needs to be indexed.

 

If the focus at the film plane and the GG are not in agreement, then the focus at the FP must be set first. This is easy to check by just running a roll of film, and using the GG to focus, while ignoring the distance scale on the focus knob. If it needs to be adjusted, then it's time to check Elek's article, as Mike Kovacs suggests.

 

There is little to cause the actual mechanical focus to change, short of dropping the camera, or messing with the regulating washers under the lens mount plate itself. That's a mess, either way.

 

Adjusting the viewing focus is a matter of removing the front facia/baffle and loosening the set screw in the top lens mount. The viewing lens can then be turned in or out, and the focus set as needed. It's on a single start thread, so there are no indexing problems, should you unthread it compleatly. There are no mirror or GG shims. Not on any of the 'Mats I've worked on, anyway.

 

Write back if you get stuck, Todd. Good luck!

All very good responses, thanks for the insight. I wasn't near my computer today so I

couldn't read the advice while I was dismantling the camera.

 

I started taking the lens hood off and ran into a problem, 2 of the 4

screws were missing. After they were removed I found a couple greasy finger prints

on the edges of the mirror, suggesting to me that it has been opened before. Being

the masculine type that I am, master of all things mechanical, telling myself "no

camera's gonna kick my butt"...I proceeded to my good friend who repairs cameras

and let him test his masculinity (he said it'll be ready tomorrow) ;-)

 

For what it's worth, the ground glass had irregular areas in focus, never all at once,

kinda' wierd but it further cemented my decision to let a pro handle it.

 

thanks again for the reponse,

 

Todd

To further speculate on your last paragraphs, the fingerprints might mean a mirror reinstalled improperly. Or...maybe the view screen was put in upside down... and that throws out of focus everything just by a millimeter or such. Let's hope the taking lens is correctly installed.

Tom, with apologies for using your thread, could I elbow in here and ask some advice please?

 

I have a Yashica 12 with a stuck shutter - someone has engaged the self-timer and the shutter won't fire. I have to get to it, but I don't know how the little circular caps that cover the shutter speed and aperture setting knobs come off. I presume I have to remove the setting knobs first, before the surrounding valance plate around the lens assembly will come off and I presume that they are fixed on by a centre nut or screw under the covers. They are so precisely inset into the knobs, that I am afraid of damaging them if I try and pry them out.

 

Any advice greatly appreciated.

Graham, The knobs for the shutter and aperture do not come off to remove the front valance. This valance, (lens surround) is held on by five little screws under the leatherette. Remove the screws, two at each side and one at the bottom, and lift the surround from the camera. Then you can take the lens out and open the shutter. The only thing in the shutter that can fly out is the click for the shutter speed detents. Just put your thunb over it when you lift off the shutter speed ring so it doesn't take flight. It's sitting right on top of the ST at the end that the lever comes out of the camera, (for setting the ST).

 

Dean

Thank you, Dean.

Todd, my 124G always focused beyond infinity. According to the screen (and confirmed on film), the actual infinity focus position is at about the 20 meter mark. I had it overhauled a few years ago by Kyocera/Contax and they left it that way. Not a problem (once I discovered it) and I'd rather have it focus beyond infinity than stop short of it. Perhaps there's a lot of individual camera variation. One more thing: I never was fond of the original Yashicamat screen so I replaced it with one from a Bronica SQA. Easy to do (requires filing off a locating tab) and much brighter, and easier to focus now. Kyocera/Contax noted the different screen but said there was no problem with focusing accuracy.