Professional Shutter Speed Adjustment places?

[rick oleson]

That is not necessarily true. In the case where you are aiming the light sensor in from the front, the light source (aluminum foil in the film gate) is about 30mm away from the sensor. At that distance, your sensor may have a field of view of 20 or 30mm. If this is the case, it could be responding to light coming from the aluminum foil over that much distance as the 2mm shutter slit passes across the film gate. This, in a shutter operating at a perfect 1/500 second, would indicate a speed as slow as 1/25 to 1/50 second. Which, by some bizarre and unexplainable coincidence, is exactly the result that you're seeing on your tester.

I'm going to stick my neck out here and speculate that there is nothing whatever wrong with the shutter in your Zorki and that the apparent incorrect readings you're seeing are 100% due to testing error.

 

[brbo]

The little unit I am using translates the length of exposure to light to a sound signal and I am using "audacity" software to measure the wave afterwards, like one normally would.
Look it up, I think there is some info on YouTube.

Yes, and unless I'm missing something I can't see how this thing could possibly give correct shutter speed readings. Especially the fast ones.

The shutter travels for much longer than 1/1000s so your thing detects light for the whole duration of the shutter travel and in effect gives much slower speed readings than the film is exposed to the light in reality. It's the width of the slit that determines the duration of exposure of film but your gadget is reading the light hitting the film area from the left to the far right edge.

What am I missing?! (Again, not an engineer )

 

[MIkhail]

That is not necessarily true. In the case where you are aiming the light sensor in from the front, the light source (aluminum foil in the film gate) is about 30mm away from the sensor. At that distance, your sensor may have a field of view of 20 or 30mm. If this is the case, it could be responding to light coming from the aluminum foil over that much distance as the 2mm shutter slit passes across the film gate. This, in a shutter operating at a perfect 1/500 second, would indicate a speed as slow as 1/25 to 1/50 second. Which, by some bizarre and unexplainable coincidence, is exactly the result that you're seeing on your tester.

I'm going to stick my neck out here and speculate that there is nothing whatever wrong with the shutter in your Zorki and that the apparent incorrect readings you're seeing are 100% due to testing error.

Now I am confused.
Apparently, I am missing something in design there (granted, I know little about Zorki design, never had an interest) but I don't understand why is the same not happening to slow speeds?

What I can do (given a free time, which I anticipate this weekend) is to run a roll of film thru with all the speeds available and see the results, how they differ. Of course, huge latitude of b/w film somewhat negates this, but hopefully... there is a difference between 1/500 and 1/45 that is bound to show.

 

[brbo]

Now I am confused.
Apparently, I am missing something in design there (granted, I know little about Zorki design, never had an interest) but I don't understand why is the same not happening to slow speeds?

It is. The relative "error" is just (much) smaller.

What I can do (given a free time, which I anticipate this weekend) is to run a roll of film thru with all the speeds available and see the results, how they differ. Of course, huge latitude of b/w film somewhat negates this, but hopefully... there is a difference between 1/500 and 1/45 that is bound to show.

You can easily spot the change in density of less than 1 stop let alone 4 or more...

 

[MIkhail]

Yes, and unless I'm missing something I can't see how this thing could possibly give correct shutter speed readings. Especially the fast ones.

The shutter travels for much longer than 1/1000s so your thing detects light for the whole duration of the shutter travel and in effect gives much slower speed readings than the film is exposed to the light in reality. It's the width of the slit that determines the duration of exposure of film but your gadget is reading the light hitting the film area from the left to the far right edge.

What am I missing?! (Again, not an engineer )

Are you saying that due to specifics of Zorki-1 shutter mechanism the gadget that I use on other cameras (and they were spot-on) is not usable? Am I understanding this correct?

 

[sevo]

Now I am confused.
Apparently, I am missing something in design there (granted, I know little about Zorki design, never had an interest) but I don't understand why is the same not happening to slow speeds?

You are aware of how a focal plane shutter works? Small camera FP shutters generally have only one speed (the one indicated as "sync speed") - for shorter times, they link both curtains so that only a slit travels over the film (shortening the exposure time for each bit of film - but the time between exposing the far left and far right edge of the film still is the sync speed). For long times, they use an auxiliary timer to delay the start of the second curtain - each curtain still needs the same 1/50s to travel across, but the second curtain does start delayed.

Your method with the reflector in the film plane would actually work, if you used a laser (or similarly narrow beam light) for illumination - but given the above, it can never measure anything shorter than sync speed if you use a light source that covers the entire film gate.

 

[MIkhail]

You are aware of how a focal plane shutter works? Small camera FP shutters generally have only one speed (the one indicated as "sync speed") - for shorter times, they link both curtains so that only a slit travels over the film (shortening the exposure time for each bit of film - but the time between exposing the far left and far right edge of the film still is the sync speed). For long times, they use an auxiliary timer to delay the start of the second curtain - each curtain still needs the same 1/50s to travel across, but the second curtain does start delayed.

Your method with the reflector in the film plane would actually work, if you used a laser (or similarly narrow beam light) for illumination - but given the above, it can never measure anything shorter than sync speed if you use a light source that covers the entire film gate.

Hmm... That’s interesting, because I used this gizmo on Leica R3, Leica M6 & Minolta X-350 - all very close or right on.
That’s all I have.
Oh, and I also used it on FED-5 (with aluminum foil) and it was also off completely. Must be because it has mechanism similar to Zorki and my method of measuring was also similar.
Thanks.

 

[rick oleson]

Mikhail, PLEASE: for the love of God, please, just one time, humor us: Take any one of those "tested just fine" cameras and test it THE SAME WAY YOU TESTED THE ZORKI. Or, maybe better yet, the Fed 5 has a removable back, test that THE WAY YOU TESTED THE SLRS.

Why are you going to so much trouble to avoid testing your methodology to find out whether it's valid?

 

[MIkhail]

Ok, so I was wrong…
I did a film test on my Zorki. I shot sequence of frames from the same spot within seconds with the following:
f3.5, 1/500;
f4, 1/250;
f5.6, 1/125;
f8, 1/60
and so forth.
They are all exposed pretty much the same as you can see..
To me this means that Zorki’s speeds are all proportionally correct.
And I think they are all about 1 stop slower than should be.

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[rick oleson]

Great news! These are really not bad cameras, and disproportionate shutter speed errors are very difficult for them to create. It could be a bit slow across the board, although a stop seems like a lot. Glad it didn't get relegated to shelf-only status!

take care

 

[wolves3012]

That is not necessarily true. In the case where you are aiming the light sensor in from the front, the light source (aluminum foil in the film gate) is about 30mm away from the sensor. At that distance, your sensor may have a field of view of 20 or 30mm. If this is the case, it could be responding to light coming from the aluminum foil over that much distance as the 2mm shutter slit passes across the film gate. This, in a shutter operating at a perfect 1/500 second, would indicate a speed as slow as 1/25 to 1/50 second. Which, by some bizarre and unexplainable coincidence, is exactly the result that you're seeing on your tester.

I'm going to stick my neck out here and speculate that there is nothing whatever wrong with the shutter in your Zorki and that the apparent incorrect readings you're seeing are 100% due to testing error.

I'd be willing to put money on this being the correct explanation, makes perfect sense, knowing how the Zorki shutter (and most FP shutters) work. It's not valid using the tester unless it's close up by the shutter's passing "slit".

Having had a few FSU shutters apart, there's precious little to go wrong unless they are gummed up or broken. It's actually very hard to get them to run at anything other than roughly the correct speeds if they are clean and free-running. All speeds may be off by roughly the same factor but not in the way reported above.

 

[MIkhail]

Great news! These are really not bad cameras, and disproportionate shutter speed errors are very difficult for them to create. It could be a bit slow across the board, although a stop seems like a lot. Glad it didn't get relegated to shelf-only status!

take care

Now that I understand a situation a bit better, I realise that in order to use this little gadget successfully I would have to put a small piece of tube over the sensor so it only reacts to a straight rays of light, not angled. Otherwise sensor does not make a distinction between light right in front of it and light coming from the side... I learned something after all.
Thanks!

 

[Steve M.]

A lot of people refuse to work on those cameras. It's like taking your Huffy to a high end bike shop. They will just shake their heads and point you toward the door. You would be about 10,000 times better off just buying a more modern and reliable camera like a Bessa R.

 

[MIkhail]

A lot of people refuse to work on those cameras. It's like taking your Huffy to a high end bike shop. They will just shake their heads and point you toward the door. You would be about 10,000 times better off just buying a more modern and reliable camera like a Bessa R.

I agree.
I just happen to have this one laying around.
When I actually go shoot I use Leica M6 and Minolta X-350. That's two cameras I have and use all the time.

 

[rick oleson]

A lot of people refuse to work on those cameras. It's like taking your Huffy to a high end bike shop. They will just shake their heads and point you toward the door. You would be about 10,000 times better off just buying a more modern and reliable camera like a Bessa R.

Ho ho ho, you make funny joke, no?