Bronica PG Lens Shutter Problem

Aidan Sciortino · Mar 8, 2021

I recently acquired a Bronica GS-1 kit with a PG 65mm f/4 as well as a PG 150mm f/4. At first I thought there was an issue with the body as I had a problem with the mirror lagging on firing the shutter, and the frame not being properly exposed. However, upon closer inspection I realized that this only happens with the 65mm attached (unfortunate as I far prefer shooting wide).

Removing the lens from the camera and activating the lever that enables it with a fingernail, I can move the cocking and firing lever, but notice that it requires a bit more force to move from it's cocked and open position into it's ready to fire state in comparison to the 150mm.

The 150mm works fine.

Is this something anyone has experience with / fixing? Would a CLA fix this? Is this something I can do myself? I have a lot of tools and a fair amount of time, in comparison to the amount of money I have. Buying a new 65mm is not an option, although I could likely afford a cheaper lens like the 50mm f/4.5 if this lens is not salvageable.

Thanks for any insight!

Aidan

Truzi · Mar 8, 2021

I have both the GS-1 and 65mm, but really don't know enough to help. You could check the contacts on the lens in case the body isn't getting good contact to sense what is going on.

Also, I don't quite have the hang of the "T" setting on the lens. It's a metal tab or slide-switch on the lens barrel that you can slide one way or the other to switch between normal operation and Timed exposure. Make sure it's in the correct position, and maybe work it back and forth a bit. I know my 100mm has it, I'm pretty sure the 65mm does.
Try page 21 (Item 15) of this PDF:
http://ianbfoto.com/downloads/Bronica/Bronica GS-1 Instructions.pdf

Those are my two guesses.

voceumana · Mar 8, 2021

Slide the T switch to permit the little metal knob to be pulled out for time exposure; shutter release opens the shutter, and then you can push in the knob and slide the switch to close the shutter or advance the film. Note that the time setting will remain in play until you push in the knob.. The slide switch is just an interlock.

Aidan Sciortino · Mar 8, 2021

voceumana said:
Slide the T switch to permit the little metal knob to be pulled out for time exposure; shutter release opens the shutter, and then you can push in the knob and slide the switch to close the shutter or advance the film.

Mine is the reverse of this. I have to pull the knob out to move the switch to time mode, and then the time mode stays active until the switch is pushed back. On mine the knob is simply an interlock.

Truzi said:
You could check the contacts on the lens in case the body isn't getting good contact to sense what is going on.

Also, I don't quite have the hang of the "T" setting on the lens. ... Make sure it's in the correct position, and maybe work it back and forth a bit. I know my 100mm has it, I'm pretty sure the 65mm does.

I've cleaned the contacts and I've done a few successful timed exposures. The lens works fairly reliably when the camera is in vertical position, or upside down. Pretty much any position except the landscape mode I use it for most!

I think the issue is with the silver cocking lever on the back of the lens, as when the lens fails to fire it does not allow the mirror to go up, or tends to lag. Similar behavior occurs if I fire without a lens and film back and block the cameras firing lever from moving with a finger.

craigclu · Mar 8, 2021

Mine gets wonky acting like this from trying to use alkaline batteries. My bodies both behave this way. I also have Pentax 67 rigs that are sensitive to the same thing and use the same battery type. Worth a try...? Siver Oxides are the ones that smooth things out for me.

Aidan Sciortino · Mar 8, 2021

craigclu said:
Mine gets wonky acting like this from trying to use alkaline batteries. My bodies both behave this way. I also have Pentax 67 rigs that are sensitive to the same thing and use the same battery type. Worth a try...? Siver Oxides are the ones that smooth things out for me.

Certainly worth a shot! Cheaper than a CLA or a new lens and they'll be more reliable with other lenses even if they don't fix my issue with the 65!

voceumana · Mar 9, 2021

Aidan Sciortino said:
Mine is the reverse of this. I have to pull the knob out to move the switch to time mode, and then the time mode stays active until the switch is pushed back. On mine the knob is simply an interlock.

That's right--I remembered incorrectly! Thanks for the correction.

4season · Mar 9, 2021

I had a 150 mm ETR lens with sluggish shutter, and found it very easy to service (for a camera lens that is) and as I recall I did the following:

Remove screws holding rear cover in place, lift away rear cover carefully, there is a spiral of flexible PCB running between this and the shutter.
Unscrew rear lens cell from shutter.
Figure out where shutter lubricants have either dried out or hardened. By manually cocking and releasing the shutter, you can probably figure this out pretty quickly. Think I only found one place, and it only called for a small amount of lubricant.
Reassemble lens.

Don't disassemble shutter except as a last resort, Seiko electronic shutters weren't designed for component-level service, and shouldn't need it.

Aidan Sciortino · Mar 9, 2021

4season said:
I had a 150 mm ETR lens with sluggish shutter, and found it very easy to service (for a camera lens that is) and as I recall I did the following:

Remove screws holding rear cover in place, lift away rear cover carefully, there is a spiral of flexible PCB running between this and the shutter.

Unscrew rear lens cell from shutter.

Figure out where shutter lubricants have either dried out or hardened. By manually cocking and releasing the shutter, you can probably figure this out pretty quickly. Think I only found one place, and it only called for a small amount of lubricant.

Reassemble lens.

Don't disassemble shutter except as a last resort, Seiko electronic shutters weren't designed for component-level service, and shouldn't need it.

Thanks for the detailed instructions! I'll grab my set of small screwdrivers and give this a shot this weekend. What lubricant did you use? Would something like sewing machine oil work?

Found a pretty sweet deal on a 50mm f4.5 and snapped it up, but if I can lubricate the 65's shutter without great monetary cost to myself I'd love to have all my lenses working.

MattKing · Mar 9, 2021

Consider a set of JIS screwdrivers!

4season · Mar 9, 2021

Aidan Sciortino said:
Thanks for the detailed instructions! I'll grab my set of small screwdrivers and give this a shot this weekend. What lubricant did you use? Would something like sewing machine oil work?.

I forgot exactly what I used, probably some sort of medium grease. Only needed a tiny bit to really smooth things out.

shutterfinger · Mar 9, 2021

TriFlow https://www.amazon.com/Tri-Flow-Squ...qid=1615350999&sprefix=triflow,aps,254&sr=8-3 or clock oil, a trace only as too much acts like glue.
https://www.amazon.com/Finish-Line-...1615351077&sprefix=finish+line,aps,263&sr=8-7
Again a small amount where metal parts slide against one another or on gear teeth.

Aidan Sciortino · Mar 10, 2021

MattKing said:
Consider a set of JIS screwdrivers!

I'd no clue about these! I'll pick some up.

shutterfinger said:
TriFlow https://www.amazon.com/Tri-Flow-Squeeze-Bottle-Lubricant-Teflon/dp/B00GC54OC2/ref=sr_1_3?crid=2TBSGRNROUD0U&dchild=1&keywords=triflow+superior+lubricant&qid=1615350999&sprefix=triflow,aps,254&sr=8-3 or clock oil, a trace only as too much acts like glue.
https://www.amazon.com/Finish-Line-Premium-Grease-Fluoropolymer/dp/B002L5YYYA/ref=sr_1_7?crid=1GK9IWA65H148&dchild=1&keywords=finish+line+bike+lubricant&qid=1615351077&sprefix=finish+line,aps,263&sr=8-7
Again a small amount where metal parts slide against one another or on gear teeth.

I'll grab some of this stuff. It looks to me like sewing machine oil has a high risk of spreading through my lens which certainly isn't what I want.

shutterfinger · Mar 10, 2021

Sewing machine oil is like WD40, dries out and leaves a sticky residue.
Check your local hardware stores or bike shops.

Dan1 · May 16, 2022

Aidan Sciortino said:
I recently acquired a Bronica GS-1 kit with a PG 65mm f/4 as well as a PG 150mm f/4. At first I thought there was an issue with the body as I had a problem with the mirror lagging on firing the shutter, and the frame not being properly exposed. However, upon closer inspection I realized that this only happens with the 65mm attached (unfortunate as I far prefer shooting wide).

Removing the lens from the camera and activating the lever that enables it with a fingernail, I can move the cocking and firing lever, but notice that it requires a bit more force to move from it's cocked and open position into it's ready to fire state in comparison to the 150mm.

The 150mm works fine.

Is this something anyone has experience with / fixing? Would a CLA fix this? Is this something I can do myself? I have a lot of tools and a fair amount of time, in comparison to the amount of money I have. Buying a new 65mm is not an option, although I could likely afford a cheaper lens like the 50mm f/4.5 if this lens is not salvageable.

Thanks for any insight!

Aidan

Were you able to fix your lens. I have identical problems with my 50mm. Did you figure out why it works in every orientation except upright? Thanks

flavio81 · May 16, 2022

Aidan Sciortino said:
I recently acquired a Bronica GS-1 kit with a PG 65mm f/4 as well as a PG 150mm f/4. At first I thought there was an issue with the body as I had a problem with the mirror lagging on firing the shutter, and the frame not being properly exposed. However, upon closer inspection I realized that this only happens with the 65mm attached (unfortunate as I far prefer shooting wide).

Removing the lens from the camera and activating the lever that enables it with a fingernail, I can move the cocking and firing lever, but notice that it requires a bit more force to move from it's cocked and open position into it's ready to fire state in comparison to the 150mm.

The 150mm works fine.

The firing of the shutter is entirely mechanical. The closure of the shutter is acted upon electronically.

So this is a mechanical issue.

One possiblity is that the lens isn't locking securely, so the angle where the lens is sitting it (in relationsip with the body) is not constant. Then, intermittently, you would have this failure. In this case you can try messing with the lens mount to see if you can get the mount springs be tighter, so the lens mount doesn't move/rotate once the lens is fitted to the body.

The other possibility MIGHT be lack of lubrication on the lens cocking system. I'd suggest removing the rear of the lens (lens mount side), being very careful with the flex contacts, and relubing everything that enables the cocking pins to rotate. You can even first flush that part with naptha and then apply lube. If I recall correctly PG lenses should use ball bearings there.

Don't touch the shutter and make sure no kind of liquid nor oil nor grease gets there.

flavio81 · May 16, 2022

Dan1 said:
Were you able to fix your lens. I have identical problems with my 50mm. Did you figure out why it works in every orientation except upright? Thanks

Check out post above.

Note that the bronica ETR and SQ lenses use basically the same system so advice for those lenses is useful for the Grand Shooting system.

Bronica PG Lens Shutter Problem

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