Question about Prontor shutter in Hasselblad CF Lenses

Grim Tuesday · May 16, 2019

I have a Hasselblad lens with a weird problem. The shutter seems to work fine at all settings except for 1 second, in which it behaves like it is in bulb mode instead of 1s. 1/2 through 1/30 all sound fine and faster than that I can't tell by ear how they sound. Does anyone have any idea what could be up? I'm trying to figure out if it's an issue that will need repairing (that is to say, eventually get worse and ruin actually important shutter speeds) or if it's an issue I can just live with because 1s exposures are useless.

KN4SMF · May 16, 2019

I'm afraid service is called for. I say this because from experience working on shutters that iris shutters are problematic in the first place.And yes, it get worse. I heard shutterfinger preach on this and discounted it, unntil I ran upon a Kodak Supermatic shutter that had been neglected. It was utterly and irreparably ruined. I've worked on Hasselblads. They're not really so special that they can't turn sour too.

Sirius Glass · May 16, 2019

+1 Time for a CLA == Clean Lubrication and Adjustment

My Hasselblad repairman recommend all Hasselblad lenses be fired 10 to 15 time at one second every three months. I set a reminder on my iPhone and computer to remind me.

KN4SMF · May 16, 2019

Sorry. I neglected to read the Prontor in the title. I'm ignorant about those.

shutterfinger · May 16, 2019

All leaf shutters use a timing delay for speeds from 1 second to 1/100-1/125, above that booster springs are employed to close the shutter faster.
If 1 second is off all other speeds will be off also.
Looking at a clock or watch with a sweep second hand and the shutter blades at the same time cock and trip the shutter on one second as the second hand crosses a second mark: the shutter should fully open and close just as the second hand reaches the next second mark. The second hand width either side of the next second mark is usually in tolerance or very close to it. Set the shutter to 1/2 second and repeat: the shutter should open and close just as the second hand reaches the mid point between the starting second mark and the next one. Tolerance is 1/2 the width of the second hand either side of the mid point between the starting and next second mark.
Continue increasing speeds one at a time and verify that the speed increases over the previous up to 1/50-1/60 then go back down verifying that the speeds get slower. This is not precise but good enough to determine if the shutter is operating close to tolerance or not. Slow 1 second and 1/2 second speeds say the shutter needs a CLA.
I have Prontor shutter repair manuals on my google drive: https://drive.google.com/drive/folders/0B1sPJkp-MdghNGM1aGY5akgtTmc?usp=sharing

RalphLambrecht · May 16, 2019

Grim Tuesday said:
I have a Hasselblad lens with a weird problem. The shutter seems to work fine at all settings except for 1 second, in which it behaves like it is in bulb mode instead of 1s. 1/2 through 1/30 all sound fine and faster than that I can't tell by ear how they sound. Does anyone have any idea what could be up? I'm trying to figure out if it's an issue that will need repairing (that is to say, eventually get worse and ruin actually important shutter speeds) or if it's an issue I can just live with because 1s exposures are useless.

I'm not sure but believe it's normal. Did you notice that these shutter times are separately marked on the lens. It simply means that during these shutter times the shutter needs to pressed. You cannot just press it once but hold it to get the entire exposure. Try it. You may be fine and need no repair.

Theo Sulphate · May 16, 2019

RalphLambrecht said:
I'm not sure but believe it's normal. Did you notice that these shutter times are separately marked on the lens. It simply means that during these shutter times the shutter needs to pressed. You cannot just press it once but hold it to get the entire exposure. Try it. You may be fine and need no repair.

On the older C lenses, both B and a set of selectable speeds were engraved in green. You are correct in that those "speeds" behaved just like B - the reason those green speeds were there was because -- if you were setting exposure by EV -- then your coupled shutter and aperture rings might result in a setting that is 4 seconds, or whatever. The green B and the green 4 are clues to let you know they're both bulb settings.

But, as far as I know, the 1 second exposure is always a timed (non-bulb) exposure - both with C and CF lenses.

Grim Tuesday · May 16, 2019

Thanks all for the thoughts, they are much appreciated.

shutterfinger said:
All leaf shutters use a timing delay for speeds from 1 second to 1/100-1/125, above that booster springs are employed to close the shutter faster.
If 1 second is off all other speeds will be off also.
Looking at a clock or watch with a sweep second hand and the shutter blades at the same time cock and trip the shutter on one second as the second hand crosses a second mark: the shutter should fully open and close just as the second hand reaches the next second mark. The second hand width either side of the next second mark is usually in tolerance or very close to it. Set the shutter to 1/2 second and repeat: the shutter should open and close just as the second hand reaches the mid point between the starting second mark and the next one. Tolerance is 1/2 the width of the second hand either side of the mid point between the starting and next second mark.
Continue increasing speeds one at a time and verify that the speed increases over the previous up to 1/50-1/60 then go back down verifying that the speeds get slower. This is not precise but good enough to determine if the shutter is operating close to tolerance or not. Slow 1 second and 1/2 second speeds say the shutter needs a CLA.
I have Prontor shutter repair manuals on my google drive: https://drive.google.com/drive/folders/0B1sPJkp-MdghNGM1aGY5akgtTmc?usp=sharing

Thanks for those manuals, they are awesome and I've been looking for them for a long time! I should be clear about what I am experiencing with this lens. It is not the garden variety shutter "slowness," where the shutter takes 2-3 seconds to close on 1s and you hear the whirring of the slow gears happen slowly. I have plenty of cameras with that problem and I chalk it up to a sticky gear train or a weak spring. In this lens, the 1s never closes at all once I press the shutter button, it just stays open as if it's in bulb mode. It closes when I unpress the shutter button. All other speeds are fine. It's really bizarre.

RalphLambrecht said:
I'm not sure but believe it's normal. Did you notice that these shutter times are separately marked on the lens. It simply means that during these shutter times the shutter needs to pressed. You cannot just press it once but hold it to get the entire exposure. Try it. You may be fine and need no repair.

In general on a Hasselblad you need to hold the shutter for the whole time to keep the "barn doors" in the back up. I learned this the hard way on my first few rolls when I got them back from the lab and some pictures had only been exposed in the middle. That particular lens had a "shutter delay" caused by need for a CLA. But I now have a (different) perfectly working CF lens and once you press the shutter button with that one, the shutter opens for 1 second and then snaps closed, so I can pretty confidently say there is a real problem with this lens.

shutterfinger · May 16, 2019

Grim Tuesday said:
I have plenty of cameras with that problem and I chalk it up to a sticky gear train or a weak spring. In this lens, the 1s never closes at all once I press the shutter button, it just stays open as if it's in bulb mode. It closes when I unpress the shutter button.

There are usually the B&T levers that move or get locked out to allow the delay timer to operate. The 1 second setting uses the full travel of the delay and I have seen some that would stick at the full retard position and operate in the partial travel, nothing mysterious.
Cock and release the shutter on 1 second but this time bump or rap it against the heel of your hand while holding the shutter button down. Did it operate without releasing the shutter button?

Shutters were usually modified for specific cameras so the LF versions listed in the manuals may not match yours exactly.

Grim Tuesday · May 16, 2019

shutterfinger said:
There are usually the B&T levers that move or get locked out to allow the delay timer to operate. The 1 second setting uses the full travel of the delay and I have seen some that would stick at the full retard position and operate in the partial travel, nothing mysterious.
Cock and release the shutter on 1 second but this time bump or rap it against the heel of your hand while holding the shutter button down. Did it operate without releasing the shutter button?

Shutters were usually modified for specific cameras so the LF versions listed in the manuals may not match yours exactly.

No luck. One thing to note is that the shutter does do the initial close to allow the aperture to stop down and barn doors to open, then opened back up and stayed open.

Edit: Interesting news. The behavior has changed from staying open as long as the shutter button is pressed to it always snapping closed instantly.

shutterfinger · May 17, 2019

Sticky/stuck lever(s).

Grim Tuesday · May 17, 2019

shutterfinger said:
Sticky/stuck lever(s).

Interesting. Would I be correct in saying it is then an "isolated" problem with the levers involved with 1s rather than a systemic problem with the shutter mechanism?

shutterfinger · May 17, 2019

No, its just showing itself at 1 second as it was/is rarely used. It will likely get worse.

Question about Prontor shutter in Hasselblad CF Lenses

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