Pronto shutter speed adjustment

[EdColorado]

I've been working on a really nice Voigtlander Vito B with a Color Scopar in a Pronto shutter. The shutter has been out and thoroughly cleaned, and it works fine, except the speeds are off. 1/25 is spot on but everything else is slow. 1/50 isn't too bad, 1/100 and 1/200 are both a little over a stop slow. I'm self learning shutters as I go here so may be missing something obvious but I cant find a speed adjustment. I've been looking for a way to move the escapement but no go. The main cocking spring seems to be the only thing driving the shutter, but perhaps there's a high speed helper spring in their somewhere?

I've been searching the web and there's plenty of writeups on cleaning, but none of them that I've found talk about adjusting after reassembly. Is this a non adjustable shutter?

A picture for reference.

 

[SalveSlog]

As far as I know (not much) you can't adjust the speed in Prontors.
Your experience with the shutter times are oppositte mine. Most of my Prontors run well on fast speeds but slow on the slower ones.
The Vito Bs are sweet little cameras!

 

[EdColorado]

Hmm, looking that way to me too SalveSlog, otherwise I'd think at least one of the writeups I've found would mention adjustment. Not a big deal I guess as I can just adjust as needed, its just that the Pronto already has only 4 speeds, and I hate to loose the fastest one. It is a sweet little camera though, certainly a keeper!

 

[shutterfinger]

I did a google search for Prontor Shutter service manual and got several useful links including this one http://benoit.suaudeau.perso.neuf.fr/manuels_rep/obturateurs/001_pdfsam_prontor.pdf
If there are no screws on the delayed action device then it running incorrectly is due to dried lubrication, dirt, over lubrication, or worn mechanism.
There may not be any direct adjustment mentioned but standard shutter operation is the lower section of the delay device, your picture at 4 o'clock, when moved closer to the center of the case speeds up the slow speeds, moved closer to the outer edge of the case increases slow speeds times. Your picture at the 1 o'clock position the closer the delay device to the center of the case the slower the faster speeds, the closer to the outer case edge the faster the high speeds.

You may need to bend the pin on the delay device at the 2 o'clock position to change the speeds. Movements of 1° or less is usually what is needed. The other way is to stake or file the speed ring at specific positions. I refrain from staking/filing the speed ring to get the speeds correct.

 

[paul ron]

they are very finiky shutters. read the manual n listen to the above advice.

did you work on the diaphram n shutter blades? gunk in there can be your problem too.

since you know which speeds n how much they are off... write it down n compensate for it.

enjoy the new camera.

 

[EdColorado]

I did a google search for Prontor Shutter service manual and got several useful links including this one http://benoit.suaudeau.perso.neuf.fr/manuels_rep/obturateurs/001_pdfsam_prontor.pdf

I already have that manual. No mention of adjusting shutter speeds.

If there are no screws on the delayed action device then it running incorrectly is due to dried lubrication, dirt, over lubrication, or worn mechanism.

There isn't any adjust-ability in the delayed action device mounting screws, and as its all been completely apart and thoroughly cleaned, I'm guessing its worn. Its very clean and was first tested with no lube, then with a couple of tiny bits of fine oil (from a local camera repair guy) with no change in operation. I think I'll probably reclean the whole thing now as I really don't want the lube to migrate to the shutter blades. I don't think there is any where near enough, but I don't want to deal with it in the future... unless you suggest otherwise.

There may not be any direct adjustment mentioned but standard shutter operation is the lower section of the delay device, your picture at 4 o'clock, when moved closer to the center of the case speeds up the slow speeds, moved closer to the outer edge of the case increases slow speeds times. Your picture at the 1 o'clock position the closer the delay device to the center of the case the slower the faster speeds, the closer to the outer case edge the faster the high speeds.

Ah OK, thanks for that. I knew about the general way to adjust low speeds but wasn't aware of the high speed adjustment. Thanks!

You may need to bend the pin on the delay device at the 2 o'clock position to change the speeds. Movements of 1° or less is usually what is needed. The other way is to stake or file the speed ring at specific positions. I refrain from staking/filing the speed ring to get the speeds correct.

I was already looking at that pin. As its my fast speeds that are off I was looking for ways to get it out farther but found its already at the limit of its travel. With that in mind, I'll be doing what Paul suggests below and just tweak my exposures a bit.

Thank you shutterfinger, I appreciate all your help!

 

[EdColorado]

they are very finiky shutters. read the manual n listen to the above advice.

did you work on the diaphram n shutter blades? gunk in there can be your problem too.

since you know which speeds n how much they are off... write it down n compensate for it.

enjoy the new camera.

Thank you Paul. That will be my future plan.
Oh and yes, the entire thing has been apart and cleaned thoroughly.(my first shutter blade reinstallation... geez, nearly drove me to drink a lot more than I already do! ) I'm going with excessive wear and am going to compensate accordingly, and enjoy this one a lot. Its not my only Voigtlander and so far I find their cameras to be very special.

 

[shutterfinger]

Shutter repair manuals are written Assuming you know the basics of shutter servicing. Teaching yourself misses some of the things they tell you in a factory training class and you must figure them out for yourself. I have a Prontor that fires at the same speed for all settings in the desk drawer, I'll get around to servicing it someday.

Look for http://www.amazon.com/DuPont-Non-St...id=1460247937&sr=8-4&keywords=dry+film+teflon Dupont Dry Film Teflon. It works really well to lubricate aperture blades, shutter blades, and delay mechanisms. Do not use any with oil on shutter or aperture blades. The pricing on Amazon has quadrupled in the last year or two, linked as sample of the desired product.

 

[John Koehrer]

Not sure why the escapement would affect higher speeds in this shutter, they normally don't.
With the age it's also possible the main spring is weak. Once upon a time before replacing parts became the norm a
technician might actually make a new one.
If you want to take a whack, you could add tension to the main spring by filing a notch a bit further toward the top.