IIIg delayed shutter

[qqphot]

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Any idea going on here? Actual exposure times are accurate - there's just a pause before it fires. Only when film is loaded, and if I fire it multiple times in a row, only the first really hesitates like this.  Everything else is perfect.  I think i've asked about this here before but the video demonstrates much better. It's had a recent CLA but maybe something was missed.

 

 

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[earleygallery]

Video not working but what you describe isn't normal and if you've had it 'cla'd' then send it back for them to do it properly!

[qqphot]

i don't know why there's a second empty video below the text but the one at the top of my post works for me at least . Strange.

At any rate, I'm interested in understanding what's going on mechanically, more than just sending it back, which I will do anyway.

Edited October 11, 2023 by qqphot

[jerzy]

I do not have an answer yet, but I have an impression that after pressing release speed dial starts to run, stops for a very short moment and then rotates further. Is it really like this? or this is only optical illusion? Speed dial runs with the firt (opening curtain) and this would mean that as well first curtain stops in the "middle" of the road

first viedo work on windows with me but not on iOS

Edited October 11, 2023 by jerzy

[qqphot]

6 hours ago, jerzy said:

I do not have an answer yet, but I have an impression that after pressing release speed dial starts to run, stops for a very short moment and then rotates further. Is it really like this? or this is only optical illusion? Speed dial runs with the firt (opening curtain) and this would mean that as well first curtain stops in the "middle" of the road

first viedo work on windows with me but not on iOS

Yes, it's exactly like that. It stop then starts again i suppose at the point where the front curtain begins moving, and *then* everything operates correctly - front curtain opens, rear curtain follows, speed is accurate. Film is exposed perfectly correctly. There's just that pause before the shutter activates.  No illusion.   And only when film is loaded in the camera.

 

Edited October 12, 2023 by qqphot

[jerzy]

it is indeed very unusual behaviour, most probably you will not be able to resolve it by yourself but if you have a film that you can sacrify you may do some experimentrs, possibly they can help in understanding. In order to have common understanding few explanations upfront: in properly working shutter, regardless what speed is set,  after you press release both curtains start to run and speed dial starts to rotate. It is only for a very short distance, depends on the camera, speed dial rotates by a distance approx between 1/200 and 1/500. Then the closing curtain is being catched, opening curtain runs further and speed dial rotates as well. There should be no stop and no resistance in movement of opening curtain and rotation of speed dial.
Depening on the speed set on the dial, during its travel the opening curtain releases the second curtain which starts to run. There should be no visible stop in this moment in the rotation of speed dial.
Back to your problem - is the rotation of speed dial until it will be shortly stoped dependent on which speed you set?
Frthermore, if you have a film to sacrify: remove the lens, set speed to B press and hold release. Speed dial shall rotate without any short stop-- does it? Shutter shall be fully opened, closing curtain shall be still non-visible.
Set speed to for ex 1/100, hold the speed dial with your fingers and press and hold release. Slightly release the pressure on the speed dial and allow it to rotate slowly. Do you feel any resistance on rotation of speed dial when the edge of opening curtain appears in the frame? Allow speed dial to rotate further, slowly. Approx at 1/4th (with speed set to 1/100) of the frame the second curtain will be released and will catch the opening curtain. If you release the speed dial  (keep release button down all the time) the shutter will stay closed in the same position until you release the button mosgt probably, this is OK.
But maybe I am wrong and the problem originates somewhere else. Similar effect I observed when the release button (flat spring at the bottom) was not adjusted correctly. But in such case there is no dependance on first or subsequent release and no dependance on loaded film

 

Edited October 12, 2023 by jerzy

[qqphot]

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47 minutes ago, jerzy said:

it is indeed very unusual behaviour, most probably you will not be able to resolve it by yourself but if you have a film that you can sacrify you may do some experimentrs, possibly they can help in understanding. In order to have common understanding few explanations upfront: in properly working shutter, regardless what speed is set,  after you press release both curtains start to run and speed dial starts to rotate. It is only for a very short distance, depends on the camera, speed dial rotates by a distance approx between 1/200 and 1/500. Then the closing curtain is being catched, opening curtain runs further and speed dial rotates as well. There should be no stop and no resistance in movement of opening curtain and rotation of speed dial.
Depening on the speed set on the dial, during its travel the opening curtain releases the second curtain which starts to run. There should be no visible stop in this moment in the rotation of speed dial.
Back to your problem - is the rotation of speed dial until it will be shortly stoped dependent on which speed you set?
Frthermore, if you have a film to sacrify: remove the lens, set speed to B press and hold release. Speed dial shall rotate without any short stop-- does it? Shutter shall be fully opened, closing curtain shall be still non-visible.
Set speed to for ex 1/100, hold the speed dial with your fingers and press and hold release. Slightly release the pressure on the speed dial and allow it to rotate slowly. Do you feel any resistance on rotation of speed dial when the edge of opening curtain appears in the frame? Allow speed dial to rotate further, slowly. Approx at 1/4th (with speed set to 1/100) of the frame the second curtain will be released and will catch the opening curtain. If you release the speed dial  (keep release button down all the time) the shutter will stay closed in the same position until you release the button mosgt probably, this is OK.
But maybe I am wrong and the problem originates somewhere else. Similar effect I observed when the release button (flat spring at the bottom) was not adjusted correctly. But in such case there is no dependance on first or subsequent release and no dependance on loaded film

 

1. same happens at all speeds, even slow speeds, including B and T. duration of the delay varies but mostly by how long since last time i fired the shutter, not shutter speed.

2. on B, it still has hesitation delay, however curtain always opens fully, no curtain edges visible

3. slowly allowing the speed dial to turn, on 1/125, there is resistance when the opening curtain edge passes the frame edge - but this is further into the rotation than where the "catch" happens.

I've now fired it enough times in a row that it is no longer showing the catch/delay, so I'll have to wait a while before trying again.

I'll attach another video shot at 960 frames/second, showing the speed dial turning in slow motion, so that you can see how early in the rotation the catch happens.

 

 

Edited October 12, 2023 by qqphot

[jerzy]

vor 4 Stunden schrieb qqphot:

early in the rotation the catch happens

good video, so it it is clear now that the short stop happens, most probably, when the second curtain is being halted and the opening curtain shall travel alone. This is how it looks under the top cover of IIIg: left picture shows shutter spanned and position of speed dial 1/500 (or 1/1000, it does not matter here). One notch, connected to speed dial rotates when opening curtain is running, the other notch (on this left picture under the first notch) is connected to the closing curtain. When you press release than both curtains rotate until notch for the 2nd curtain (I mean closing curtain)  reaches point A on the latch. From this point only the opening curtain shall run. And it has short delay here. One of the reasons could be that the big shutter drum is dirty/sticky. There is slight possibilty that the reason could be misadjusted flash contact F. In any case, the repair person will benefit from knowing the video.

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Edited October 12, 2023 by jerzy

[qqphot]

Thank you Jerzy, I always learn a great deal from your observations and explanations!