PDA

View Full Version : finder needle weird behavior / off-centered?


Jutzuro
08-29-2009, 10:17
Hello mates,

I am a novice in film photography. I would appreciate any help on how to bring this fantastic rangefinder back to normal operation.

I have installed a 1,5v alkaline battery into my Olympus RC. In A mode the finder needle only shows the F stop when the shutter is fully released. The needle seems to be stuck at f22 and struggles to advance. Since the shutter locks sometimes, and sometimes it does not, I assume that the cell is working but I think it should give me the F stop reading before the shutter activates.

In manual mode the needle points at the F stop sometimes when half pressing the shutter release button, but it seems that it struggles to pass f22. The rest of the attepts, it only moves when the shutter has already fired.

Both in A and manual mode the F stop indicated by the needle seems to correspond to the actual apperture chosen either by the camera or by me. Besides that, in Flashmatic mode the needle seems to move across the Fstop range properly.

Another related question is that the needle seems to be off-centered. Whet it locks it does next to f2.8, not in the red area. When it manages to point at the F stop, it never stops "on" the F number but on the right side of it. However, in Flashmatic mode in which it seems to point "on" the numbers.

Do you think that the needle mechanism is broken? or is this normal? Thanks a lot to everybody.

Jutzuro

sevo
08-29-2009, 10:34
IIRC it follows the usual pattern for automated mechanical apertures and shutters: The release first closes a contact that activates the meter. As you press it further, it first locks the needle in place, and the finger pressure then runs a shutter or aperture setting lever against a rear tab on the meter needle hub to transfer the value. It may take some cleaning and bending of contacts and adjustment of levers to get it all back into the proper sequence.

Jutzuro
08-30-2009, 07:32
IIRC it follows the usual pattern for automated mechanical apertures and shutters: The release first closes a contact that activates the meter. As you press it further, it first locks the needle in place, and the finger pressure then runs a shutter or aperture setting lever against a rear tab on the meter needle hub to transfer the value. It may take some cleaning and bending of contacts and adjustment of levers to get it all back into the proper sequence.

I am new to all this. I have seen the drawings of Rick Oleson. I think the camera is metering properly and the only problem concerns the aperture needle and its link to the shutter. But how will I see which levers have to be adjusted? Do you think that this will be too much for a newbie?

Thanks

John Hermanson
09-03-2009, 10:38
When set to "A", the RC meter is always on. As you slowly press the release down, a pair of metal blades come down and trap the meter needle at whatever position it is. This position corresponds to a certain f stop. The viewfinder needle should show you the f stop the camera is going to use. If you are in a lighting situation that is unusually dark or very bright and you are set to shutter speeds that cause the meter to be outside its usable range, the meter needle will be too low or too high and the trap mechanism will come down and lock the shutter. If shutter is locking and you're sure the shutter speed, asa, lighting condition are within the range of the meter, then the meter may not be working (could be caused by corroded battery contact/corroded wire, dirty on/off switch, bad meter coil, bad trap mechanism. John, www.zuiko.com

Jutzuro
09-04-2009, 05:14
Hi John and thanks for your reply,

I have seen that one of these metal blades (the dented one) seems to trap the meter needle a bit too late (when the shutter has already fired or simultaneously). Therefore I think it results only in occasionaly good exposures in A mode. In manual mode, however, 90% of the times the aperture needle shows the selected f stop before the shutter fires.

I have also seen that there is a screw in the mechanism of one of these two blades that influences the position of the viewfinder needle (more to the right or to the left of the f stop scale). That is why I was also talking about an "off-centered" needle.

I haven't open the top plate yet because one of the screws is a bit stuck and I need a proper screwdriver.

What do you think I should adjust in order the solve the aperture needle/shutter issue?

Thanks a lot
-J

John Hermanson
09-04-2009, 12:58
This is a defect that requires a repair, not an adjustment. Honestly, you should be able to look at the mechanism and just figure it out. If you start turning adjustment screws (some of which are factory set and never adjusted again) you'll end up with a camera with a trap mechanism that thinks the meter is at 5.6 when it's really at 8 or 11 and the lens is opening to f4. Everything has to jive and match at the correct light levels. Otherwise it's a case of "I'll turn this and hope it fixes itself". John

Jutzuro
09-05-2009, 05:17
Wel I have opended it up, anf my conclusion was that the mechanism of the dented blade was acting too late with respect to the shutter actuation. I apologize for my english and I will try to descrive what I did as accurately as possible. I have unscrewed the golden screw near the bottom of the lens barrel holding the two mechanisms of the two blades that operate on the meter needle and removed a sort of black metal spring than seems to boost the dented blade mechanism when the shutter is pressed. I have gently bent this spring in the same direction it is supposed to act and then proceeded with the reassembly. Now, the aperture needle shows the f stop before the shutter fires and I can say the A mode is usable again. Despite this success, I have to say that the mechanism still seems a bit "sticky" and therefore unreliable, specially if the shutter button is pressed too fast and I will have the camera serviced as soon as I can.

Regards,

-J