Bronica ETRSi Mirror up fault...

Greetings! and thanks for any help.

I have two lenses for the ETRSI, a PE 75mm f/2.8 and a PE 150mm f/3.5. The mirror up shutter release seems to work properly on the 150mm but does not on the 75mm. There is the snick of the shutter firing but no apparent apperture motion and frames exposed with mirror up are blank. I read elsewhere on this site after a Google search that these shutters are mechanically activated but electronically timed. So it seems to be a problem with the lens.

So the question is: what, if anything, can I check or clean or tweak on the 75mm to try to get the electronic timing functionality to work? I'm hoping it's a swab or dust removal type fix but am afraid it's a deeper problem.

Any info you can pass along would be a great help.
Thanks! ...edN

Your question is hard to parse, it's not clear if you are talking about the mirror lock up lever, the shutter release, or something that happens only when firing the shutter with MLU engaged.

The mirror lock up should be pretty independent of the shutter release. You turn the MLU lever and the mirror flips up and lens shutter closes. Then you fire the shutter with the usual button or cable. The shutter is electronically timed whether or not the MLU lever is engaged.

You can test the lenses and camera without film by engaging the multi-exposure lever, so that you can "wind" and cock the shutter, and see what it's doing when you fire. Try that. Try firing the shutter with and without the MLU lever engaged. You should see the lens stop down to the taking aperture, shutter open and close. Then when you wind it opens again. If you try this without a battery, each lens should open for 1/500. If the lens shutter never opens at all when fired, then the problem is in the lens shutter, but it's deeper than simply the electronic timing.

Thanks for your help.

The use case is exposing film with MLU to minimize camera shake, particularly with long exposure times.

The two lenses behave differently with the same camera settings:
* multiple exposure lever engaged
* shutter cocked
* mirror lock up in vertical position
* shutter speed set to 2 seconds

The 150mm lens exposes the shutter when the lock up lever is engaged and the aperture opens for 2 seconds and then closes when the front shutter release is pressed.
The 75mm lense exposes the shutter when the lock up lever in engaged but the aperture does not open when the front shutter release is pressed.

Similarly when a release cable is attached.

I did the same experiments with the film back removed. I was visually obvious that the aperture did not open during the 75mm MLU trial. I'm reporting the trials I did this morning using the 2sec exposure time; I used other speeds yesterday prior to writing the first version of this post.

I hope that is a more useful description. Thanks for your help.

...edN

I'm sorry if it seems like I'm interrogating you, but it is still not fully clear what you have tested.

- Try testing looking through and firing the shutter without the mirror lock up lever engaged. Do both lenses function normally?

- Your result on the 150mm lens says "exposes the shutter when the lock up lever is engaged and the aperture opens for 2 seconds and then closes when the front shutter release is pressed." This is unclear on the sequence of events. At first I thought you meant it opened the shutter when the MLU lever was engaged, which should not happen. But maybe you meant "closes the shutter when MLU is engaged, and when the shutter button is pressed, it opens for 2 sec and then closes again." The way you wrote it is unclear about whether the release button is opening or closing the shutter.

- There are some other caveats about releasing the MLU lever without wasting a frame, and operation with the AE prism, that probably don't apply here, but you can read the ETRSi manual for more information.

It turns out I have at hand an ETRS body (no MLU), not an ETRSi, so I can't test it right now, but it would be somewhat surprising to have a lens that functions normally without MLU and misfires with MLU.

- Without mirror lock up both lenses function normally. In the sense they both fire the leaf shutter.
- Sequence of events: cock shutter, activate mirror lockup, press shutter button, and then immediately lower the mirror lock-up to its default position. Repeat.
- This sequence causes the shutter to fire on the 150mm lens but does not on the 75mm lens.
- In fact I am using the AE prism (with the power off.) As I understand it, the mirror lock up is to be moved to its default position as soon as the shutter has been fired. (In the case of the 75mm lens, doing so actually completes the shutter firing that was initiated while the mirror was raised.)

I can't argue with your note of surprise over this problem. Except to speculate that there is something about the shutter speed circuitry that 'works' on the 150mm lens but does not work on the 75mm lens. I would have assumed there was some sort of electrical connection that passes a shutter speed voltage/pulse from the camera to the lens. If I'm right, the signal path functions on the 150mm but does not on the 75mm. Maybe it's just a dirty connection point on the lens but i don't see anything obviously corroded and off colour on the lens. But I don't know where to look or for what.

I'm long away from the world of hybrid mechanical / electrical cameras; my last one was a Nikon F/N70 -- not one of my favourite Nikons.

I had the same problem with an SQA and a zoom lens. When using MLU, the mirror was raised, the shutter in the lens was closed, but no exposure took place. The problem was purely mechanical. Due to excessive friction in the shutter mechanism, the force of the spring in the camera body's release mechanism was not sufficient to open the shutter.

After a CLA of the lens, everything worked again as it should.

Klaus_H said:

I had the same problem with an SQA and a zoom lens. When using MLU, the mirror was raised, the shutter in the lens was closed, but no exposure took place. The problem was purely mechanical. Due to excessive friction in the shutter mechanism, the force of the spring in the camera body's release mechanism was not sufficient to open the shutter.

After a CLA of the lens, everything worked again as it should.

Click to expand...

Thanks for this. So you're saying that other lenses in your kit worked properly using MLU; it was just the zoom lens that did not fire properly?

I have 10 lenses for SQA and 4 bodies. The problem with the zoom lens occurred on all bodies. All other lenses worked perfectly on all bodies.

Klaus_H said:

I have 10 lenses for SQA and 4 bodies. The problem with the zoom lens occurred on all bodies. All other lenses worked perfectly on all bodies.

Click to expand...

Great information! Thank you. I think I'm at the point of trying to find someone knowledgeable here in Toronto or, hopefully, near by -- to take a look at that lens.

eenixon said:

I can't argue with your note of surprise over this problem. Except to speculate that there is something about the shutter speed circuitry that 'works' on the 150mm lens but does not work on the 75mm lens. I would have assumed there was some sort of electrical connection that passes a shutter speed voltage/pulse from the camera to the lens. If I'm right, the signal path functions on the 150mm but does not on the 75mm. Maybe it's just a dirty connection point on the lens but i don't see anything obviously corroded and off colour on the lens. But I don't know where to look or for what.

Click to expand...

Thanks, that makes it clearer. If you have the AE prism off then it shouldn't affect anything (although you could always try removing the prism) - I think Bronica's main concern was to notify users that the AE prism doesn't work in A mode with the mirror up, for obvious reasons.

The electronic camera-lens communication is relatively simple - the camera senses a couple of signals from the lenses, and sends hold-open power to the electromagnet in the lens to electronically time the shutter. If the lens doesn't get that power, it should still fire at the 1/500 speed. All of the ETR series, and all of the SQ series except the SQ-Ai, should fire mechanically at this 1/500 speed; the lens should fire at 1/500 even if you take the battery out. (The SQ-Ai doesn't because it has an electrical release, and the GS has a different arrangement). So, when the lens shutter is not opening at all, that suggests something in the lens is faulty, beyond the electrical connection. Klaus's first-hand experience is more definitive.

reddesert said:

Thanks, that makes it clearer. If you have the AE prism off then it shouldn't affect anything (although you could always try removing the prism) - I think Bronica's main concern was to notify users that the AE prism doesn't work in A mode with the mirror up, for obvious reasons.

The electronic camera-lens communication is relatively simple - the camera senses a couple of signals from the lenses, and sends hold-open power to the electromagnet in the lens to electronically time the shutter. If the lens doesn't get that power, it should still fire at the 1/500 speed. All of the ETR series, and all of the SQ series except the SQ-Ai, should fire mechanically at this 1/500 speed; the lens should fire at 1/500 even if you take the battery out. (The SQ-Ai doesn't because it has an electrical release, and the GS has a different arrangement). So, when the lens shutter is not opening at all, that suggests something in the lens is faulty, beyond the electrical connection. Klaus's first-hand experience is more definitive.

Click to expand...

OK. More great info. I'll double check that I'm not missing the shutter firing at 1/500th of a second with mirror up on the 75mm. Over the course of testing, I think I've seen both shutter fire and no shutter fire with this scenario.
I'm in touch with a shop, Downtown Camera, where I bought this rig and who has a repair department. There is a shop in Québec City that advertises Bronica repair expertise but I'd rather stay as close to home as possible.
Thanks again both of you for your help. ...edN

Welcome to Photrio!

Since the mirror works for the 150mm lens, have the 75mm lens checked by a camera repair man or woman.

eenixon said:

I can't argue with your note of surprise over this problem. Except to speculate that there is something about the shutter speed circuitry that 'works' on the 150mm lens but does not work on the 75mm lens. I would have assumed there was some sort of electrical connection that passes a shutter speed voltage/pulse from the camera to the lens.

Click to expand...

Your problem is fully mechanical. The shutter opens via mechanical means, and electronics prevent it from closing it immediately. With zero electrical power, the shutter closes immediately after opening, which means it "fires at 1/500" speed.

When hitting the mirror up lever, the shutter cocking arm moves partially. This arm is coupled to the lens. Excessive friction in either the lens or the camera (or both) will means this won't work correctly.

When you are not using MLU, the shutter cocking arm moves fully from start to finish and thus there is more inertia/force available. So you don't experience the problem.

Additionally, if the lens mount is not tightly coupled but it is loose, the shutter will not fire. This can happen with or without mirror lock up.

Klaus_H said:

I had the same problem with an SQA and a zoom lens. When using MLU, the mirror was raised, the shutter in the lens was closed, but no exposure took place. The problem was purely mechanical. Due to excessive friction in the shutter mechanism, the force of the spring in the camera body's release mechanism was not sufficient to open the shutter.

After a CLA of the lens, everything worked again as it should.

Click to expand...

+1 great advice.