FTb shutter capping at 1/1000

[h_s1]

TL;DR: Cleaned slow speed governor, shutter spindles, speed linkages with naphtha, put extra tiny droplets on SSG, on ends of shutter spindles, but get severe capping at 1/1000. 1/500 seems fine. Did I not oil enough? Where do I apply lube, oil or grease, or what adjustment should I make to get 1/1000 working on my FTb?

 

Long version:

 

I have an FTb that I bought off ebay for cheap a while ago. Someone seems to have struggled with the speed selector pin screw and also with the winding crank. Having opened the top and bottom of Canon old SLRs in the past, I decided to take a look inside.

 

Using various online helpful posts and resources, I ended up removing the meter rack assembly, shutter speed plate (not really needed to be removed, could have just disconnected the speed display string), the prism assembly, the CdS cell behind the focusing screen and under the eye piece, the leatherette, the stop down arm, unsoldered the green wires near the galvanometer and finally got the mirror box out.

 

I used some naphtha for the slow speed governor assembly at the bottom, on shutter speed links, on curtain spindles, on the timer mechanism and also around the sides of the mirror box.

 

I was very very sparing while applying oil on the slow speed governor and on the shutter speed links. Used a needle on a syringe dipped in oil. I could barely even see the droplet on the needle tip, it was that sparing.

 

Anyhow, so far so good.

 

Couple of things I noticed:

1. There apparently was no ND filter in front of the CdS cell. Is there supposed to be one?

2. The slow speed link (which I could post the photo I took here!!), was resting on the base at the bottom, no special bushing or housing or anything. Slow speeds work fine, 1 second is almost dead on, 1/2 as well, can't tell with 1/4 and 1/8. Is this correct that the link will just rest at the bottom without any busing to support it?

3. The following needle link seems to be not fully responsive to the stop down arm (?) on the side of the box.

 

Put everything back together. All went well. The speed dial string was a bit fiddly and tricky.

 

Good things: The timer that was sluggish to begin with is prompt and responsive. 1 sec speed is good. So is 1/2.

 

However, some issues and questions:

 

The 1/1000 shows severe capping: the curtains travel, but I do not see any light when viewing from behind with no lens attached. Maybe a blink once or twice, but usually nothing. How do I fix the capping? Do I need to apply more oil after the naphtha cleaning?

 

The following needle needs "coaxing" to follow the stop down arm. Almost like it is getting some friction or the spring lacks tension. How do fix this? Lacking grease on the side of the mirror box?

 

Thanks!

Edited December 20, 2021 by h_s|1

[JDMvW]

I've never had a FD camera cap, with old Prakticas, Pentaxes and that ilk, I've found simple exercise works better than anything else I've tried

 

but as for

 

apply lube, oil or grease

 

 

NEVER. EVER.

 

Naptha is ok if used judiciiously, but you've tried that.

 

I'm not joking when I suggest that maybe 1/1000 doesn't seem to be a critical need. :|

[jim_bielecki1]

I had an old Canon FP (basically a FTb without the meter) that showed capping at fast speeds. I fixed mine by adjusting the speed of the first curtain. Take off the bottom plate and you'll see the shutter curtain adjustment screws. By slightly increasing the spring tension of the first curtain, you'll make it travel faster which will eliminate the capping. Disclaimer: the best way to stop capping is to take apart the shutter, clean everything, and reassemble. What I did works, but most repair techs frown on adjusting curtain tension to fix a capping shutter.

 

YouTube has several videos on how to fix a capping shutter. Doesn't matter the brand of camera, virtually every horizontal focal plane shutter camera of the 60's and 70's, were constructed the same way. All have shutter speed adjusting screws. I believe I used a Pentax video to help me with my FP.

 

As for your other problems, that's for another day.

[h_s1]

The stop arm and the aperture needle sticking problem is solved. Opened up the mirror box and noticed the linkages on this side needed cleaning and oil.

 

Now I am left with the 1/1000 shutter showing extreme capping, or the shutter are stuck together.

[h_s1]

Here is the photo I was referring to in my original post. The magenta arrow points to the location at the bottom of the slow speed link (?) and whether it needs some bushing to be present? I guess maybe not, since slow speeds seem to work fine.

 

[jim_bielecki1]

That rod is the slow speed link. No housing at the base, but there should be a support "extension" on the bottom.

[brett_rogers]

Unless I missed it; I don't think you have mentioned how you are assessing the accuracy of the times. It's not possible to determine the accuracy of the high speeds by eye with any precision.

 

The fastest speed of a focal plane shutter will nearly always be the one most likely to first play up. It runs the tightest slit and is always most sensitive to variations in curtain performance due to age and need for servicing. The scenario you've presented is therefore not unusual.

 

In order to rectify the problem fully, you need a means of measuring the exposure across the film gate.

 

Obviously, the first curtain is dragging. The FT series are a quality mechanism so it is less likely the cause is excessive wear unless your particular example has been used very hard. This suggests to me it could do with more cleaning. You can increase the tension of the first curtain to get it moving faster. But if the mechanism is clean and correctly lubricated it ought not be necessary to add much extra.

 

Curtain condition is always worth checking. Some makers curtain material ages much better than others. I like old German cameras, too, but Exaktas for instance, no matter how competently serviced, may never run to spec until their old and stiff curtains are replaced. Curtains that are no longer supple, even when correctly adjusted, will not have the same rate of acceleration or maximum speed because they'll no longer spool sweetly around their drums. I'm not saying this is an issue with the Canon. Merely, that curtain condition can never be overlooked when diagnosing erratic performance.

 

You must appreciate that in the first instance, the goal of balancing the curtain speeds is to achieve even exposure across the film gate. This may or may not produce an amount of exposure that is accurate at faster speeds. The amount of exposure is a product of the curtain running speed and the distance between the curtains. The slit is determined not by the curtain speed in the first instance, but by the curtain timing mechanism.

 

If the factory set timing calibration is intact, it's true that correcting the running speeds would then see the exposure fall into spec. But curtain adjustment will be right when the travel times are to spec, not necessarily when exposure is accurate, because it is possible the second curtain release delay may also need adjustment. The take away is that curtains, curtain running speed, and curtain timing, must all be good, to achieve accurate and consistent exposure.

[h_s1]

Unless I missed it; I don't think you have mentioned how you are assessing the accuracy of the times. It's not possible to determine the accuracy of the high speeds by eye with any precision.

 

The fastest speed of a focal plane shutter will nearly always be the one most likely to first play up. It runs the tightest slit and is always most sensitive to variations in curtain performance due to age and need for servicing. The scenario you've presented is therefore not unusual.

 

In order to rectify the problem fully, you need a means of measuring the exposure across the film gate.

 

<snipped>

 

If the factory set timing calibration is intact, it's true that correcting the running speeds would then see the exposure fall into spec. But curtain adjustment will be right when the travel times are to spec, not necessarily when exposure is accurate, because it is possible the second curtain release delay may also need adjustment. The take away is that curtains, curtain running speed, and curtain timing, must all be good, to achieve accurate and consistent exposure.

 

 

Thank you for explaining this! Learned a lot from your message.

 

Currently I am doing a ball park check. 1 sec with a clock. 1/1000 by comparing the brightness I perceive, by pointing the camera with no lens to a bright light source or the sky, to the one I perceive using my FT that works reasonably well (based on films I shot with it).

 

The 1 sec was easy to guess that it is fairly good, but the 1/1000 showed no light at all and a partial blink sometimes. So I knew it was wrong.

 

From your message I understand that once the FTb passes the above two approximate tests, I will eventually need a way to verify the shutter curtain travels more accurately.

 

Also, I opened the camera again and cleaned the shutter spindles again but that didn't help. What eventually helped was adjusting the curtain spring tensions. The 1/1000 is markedly improved! I still see brightness shading from start of travel to end of travel of curtains (looks like either first is faster, or the second is slower), so now the challenge is to set the tension to be equal in both the curtains.

[steven_endo]

Currently I am doing a ball park check. 1 sec with a clock. 1/1000 by comparing the brightness I perceive, by pointing the camera with no lens to a bright light source or the sky, to the one I perceive using my FT that works reasonably well (based on films I shot with it).

 

The 1 sec was easy to guess that it is fairly good, but the 1/1000 showed no light at all and a partial blink sometimes.

 

Many years ago, I did a similar "ball park" test. However, intead of just using a bright light pointed at a white wall, I used an electronic flash. At the x-synch speed (1/60), you should be able to see the full frame. At 1/125, you will only see the left 1/2 of the frame. At 1/250, the left quarter of the frame, etc. It's easier than judging brightness.

 

Admittedly, this will only test the exposure relative to 1/60. But it will tell you if the curtains are working correctly.