Olympus OM1n - Exposing with DOF button pressed?

Craig Kneale · Nov 14, 2020

Hi there,

I have a query about the Olympus OM1n.

I have an issue with the camera where the mirror jams up when I hit the shutter release.

The mirror does come back down and the photo takes if I hold in the DOF preview button on the lens.

my question is - will my film still expose as normal if this DOF button is held whilst shooting?

Thanks,

craig

chriscrawfordphoto · Nov 14, 2020

Yes, the film will expose normally if the DOF button is pushed at the moment of exposure. All it does is stop down the lens. Two things to consider:

1: Set exposure before pushing the DOF button. The camera's meter is designed to meter with the aperture open, so metering with it stopped down will give incorrect readings.

2: Something is very wrong with your camera, and it needs serviced. Whatever it is may be causing other problems like the shutter not firing at the correct speeds, etc.

MattKing · Nov 14, 2020

Is the lens aperture moving sluggishly, or not at all?
The apertures on the 50mm f/1.8 lenses often need to be cleaned due to migration of lubricant.
Based on your other thread (which you could have simply continued) it sounds like it is either the lens or its coupling with the camera that is malfunctioning. Do you have another lens you can try?

Craig Kneale · Nov 14, 2020

Hi Chris,

Thanks for the swift response and your very useful answer.

I’m actually on a photography job on an island for the next week so won’t be able to get the camera serviced until I’m home.

Do you reckon this DOF button workaround will work for me until I get home and can get it seen too?

The aperture ring seems to be closing to the right point when exposing with the DOF preview pushed down and the shutter speed dial seems to be correlating correctly to what I have it set at.

Thank you,

craig

Craig Kneale · Nov 14, 2020

MattKing said:
Based on your other thread (which you could have simply continued)

My apologies Matt - I’m new to this forum so I didn’t know the rules.

MattKing said:
Is the lens aperture moving sluggishly, or not at all?

the aperture ring seems to be moving fine and with DOF preview pushed down the blades are closing at the right increments as I move the ring around.

I think you may be correct about the coupling between the camera + lens.

Do you think it is safe to keep shooting with this DOF button workaround until I can get the camera checked out when I’m back home?

Thanks,

Craig

shutterfinger · Nov 14, 2020

I'm not familiar with Olympus cameras but many aspects are common in all brands. Auto aperture lens stay at their maximum aperture regardless of the aperture ring setting. The aperture ring provides a stop that the camera body closes the aperture down to during exposure and it also tells the camera meter the selected aperture. This is all done via levers. This repair article https://learncamerarepair.com/downloads/pdf/CameraCraftsman-olympus-om1.pdf shows some clear pictures of the aperture levers on both the lens and body. The levers should be 90° to the lens barrel and camera body. A 5° bend can prevent the lever from coupling properly.
An examination of the lens and body will quickly show if one of the levers is bent. There is also a factory service manual and battery conversion article at https://learncamerarepair.com/product.php?product=81&category=2&secondary=9

MattKing · Nov 14, 2020

Craig Kneale said:
My apologies Matt - I’m new to this forum so I didn’t know the rules.

Don't worry, it is more an issue of practicalities than rules.

Craig Kneale said:
the aperture ring seems to be moving fine and with DOF preview pushed down the blades are closing at the right increments as I move the ring around.

I'm asking more about the aperture itself than the ring.
To test this, turn the camera around, and watch the aperture itself as you take a picture/release the shutter. If the aperture is slow in responding as it tries to open up, you will see the problem.
In essence, the DOF lever mechanically couples the aperture ring to the aperture itself. You are using it to circumvent the really useful open aperture metering system that the OM system uses.

beemermark · Nov 14, 2020

Take the lens off and fire the shutter, is the mirror returns then the lens is at fault. If it doesn't then the camera needs serviced.

MattKing · Nov 15, 2020

beemermark said:
Take the lens off and fire the shutter, is the mirror returns then the lens is at fault. If it doesn't then the camera needs serviced.

Actually, I would suggest testing with another lens as well.
The problem could be in the linkage between the camera and lens, and could originate on either the lens side of the linkage, or the camera side, or both.

Craig Kneale · Nov 15, 2020

MattKing said:
Actually, I would suggest testing with another lens as well.
The problem could be in the linkage between the camera and lens, and could originate on either the lens side of the linkage, or the camera side, or both.

I think that your diagnosis is correct Matt. The camera fires fine with the lens removed (mirror goes up and comes back down as expected).

The lens seems to be working fine on its own too (just to check - when changing through the aperture - the blades should only show when the DOF preview is pressed right?)

When the camera is reassembled though - once the shutter release is pressed - the aperture ring sticks at about f4 (regardless if the aperture is set below that at 1.8 or 2.8) and only finishes the exposure by either pressing the DOF preview or switching the mirror lock.

The camera appears to fire as normal if the DOF button is held as I press the shutter release.

My question is this - will this DOF workaround do me until I finish this job and can get it to a repair shop next week? I would meter my shots as normal and then only hold the DOF button just before I press the shutter release.

Thanks,

craig

Quendil · Nov 15, 2020

Craig Kneale said:
I think that your diagnosis is correct Matt. The camera fires fine with the lens removed (mirror goes up and comes back down as expected).

The lens seems to be working fine on its own too (just to check - when changing through the aperture - the blades should only show when the DOF preview is pressed right?)

When the camera is reassembled though - once the shutter release is pressed - the aperture ring sticks at about f4 (regardless if the aperture is set below that at 1.8 or 2.8) and only finishes the exposure by either pressing the DOF preview or switching the mirror lock.

The camera appears to fire as normal if the DOF button is held as I press the shutter release.

My question is this - will this DOF workaround do me until I finish this job and can get it to a repair shop next week? I would meter my shots as normal and then only hold the DOF button just before I press the shutter release.

Thanks,

craig

Hi Craig

The DOF work around should be fine until you get it serviced. The problem could be either with the camera itself or the lens. Like other people have suggested if you get a chance to try another lens do so before having the camera serviced. I have a OM fit zoom somewhere you can have to test your camera when you get back home.
Thanks
David

reddesert · Nov 15, 2020

Craig Kneale said:
I think that your diagnosis is correct Matt. The camera fires fine with the lens removed (mirror goes up and comes back down as expected).

The lens seems to be working fine on its own too (just to check - when changing through the aperture - the blades should only show when the DOF preview is pressed right?)

When the camera is reassembled though - once the shutter release is pressed - the aperture ring sticks at about f4 (regardless if the aperture is set below that at 1.8 or 2.8) and only finishes the exposure by either pressing the DOF preview or switching the mirror lock.

The camera appears to fire as normal if the DOF button is held as I press the shutter release.

My question is this - will this DOF workaround do me until I finish this job and can get it to a repair shop next week? I would meter my shots as normal and then only hold the DOF button just before I press the shutter release.

Yes, the aperture on an Olympus OM lens should be full-open with the lens off the camera until the DOF button is pressed. When the shutter is fired on an OM, a lever at the viewer's right side of the lens mount moves up to push a lever on the lens mount, stopping down the lens. When the mirror comes back down, the camera lever comes back down. If the camera lever is prevented from moving down freely, the mirror will not come down.

On the lens, if you set the aperture to an intermediate stop like say f/8, you can test whether the lens stop-down lever (the one on the rear of the lens mount, not the DOF preview button) is moving freely by moving it with your finger.

My guess is that one or both of these levers are bent (possibly from mounting/dismounting the lens hastily), causing drag that prevents full actuation of the aperture until you force it with the DOF button. Or maybe your aperture is extremely sticky, but then the DOF button probably wouldn't stop it all the way down.

Pressing the DOF button before exposure shouldn't hurt the mechanism. However, a suggestion for the future: Photo gear is relatively inexpensive now, compared to your time. If you're going to do a job (especially on an island) you should bring a backup, eg a second body and second lens.

shutterfinger · Nov 15, 2020

reddesert said:
My guess is that one or both of these levers are bent (possibly from mounting/dismounting the lens hastily), causing drag that prevents full actuation of the aperture until you force it with the DOF button. Or maybe your aperture is extremely sticky, but then the DOF button probably wouldn't stop it all the way down.

+1

Craig Kneale · Nov 15, 2020

Quendil said:
I have a OM fit zoom somewhere you can have to test your camera when you get back home.

Very kind offer David - thank you very much. I may take you up on this when I get back home - thank you!

Craig Kneale · Nov 15, 2020

reddesert said:
My guess is that one or both of these levers are bent (possibly from mounting/dismounting the lens hastily), causing drag that prevents full actuation of the aperture until you force it with the DOF button. Or maybe your aperture is extremely sticky, but then the DOF button probably wouldn't stop it all the way down.

I think this may be the case. Is this something I could fix myself or should I take it in for repair when I get home?

reddesert said:
Photo gear is relatively inexpensive now, compared to your time. If you're going to do a job (especially on an island) you should bring a backup, eg a second body and second lens.

The job is mainly digital - the film shots are just for additional footage. I also have a Leica CL with me so can use that as a back up film camera - but I am much more fluid using the OM-1 - hence why I wanted to see if I could continue using it with the DOF workaround.

Thank you for your advice!

shutterfinger · Nov 15, 2020

Craig Kneale said:
I think this may be the case. Is this something I could fix myself or should I take it in for repair when I get home?

Got a cell phone? Yes= take a picture of the camera opening as straight into the lens opening as possible and one of the rear of the lens straight into the lens also. Be sure to capture the edges of the mount then post them here. The bend can be left/right or front/rear. Knowledge of straightening levers will be helpful and seeing the potential bend will help us direct you to straighten it if possible without any disassembly.

omtech1 · Dec 1, 2020

Craig Kneale said:
Hi there,

I have a query about the Olympus OM1n.

I have an issue with the camera where the mirror jams up when I hit the shutter release.

The mirror does come back down and the photo takes if I hold in the DOF preview button on the lens.

my question is - will my film still expose as normal if this DOF button is held whilst shooting?

Thanks,

craig

Sounds like lens is preventing shutter from firing. Lens needs service at least.

Olympus OM1n - Exposing with DOF button pressed?

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Olympus OM1n - Exposing with DOF button pressed?

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