Hi folks. I have a problem that has me stumped.

Im using an OM-5 camera in an AOI housing. Has served me superbly well for years and tens of thousands of photos with 30mm, 60mm, 14-42mm lenses.

Ive just added an Olympus 9-18mm lens and suddenly have a problem I've not seen before.

Im shooting with a pair of AOI QR Strobes using RC mode TTL. Same settings I always use and which deliver consistent great results.

However, with the 9-18mm lens 9 out 10 photos are massively under-exposed. Near black. The flashes fire but the image is near dark.

At first I thought I might have accidentally bumped the exposure compensation setting down. But that wasn't it.

Ive tried changing all the exposure settings - shutter speed, iso, fstop - doesn't matter what I choose, 9 out of 10 are near black...

Both flashes are firing, image should be lit up bright, but still I get super dark, near black images.

But then it will suddenly expose correctly - 1 out of every 10 or so. Then back to near black.

I thought it might have been a camera issue so swapped out other lenses - they worked perfect every time. Then I put the 9-18mm back on and the problem returns.

Im stumped...!

What could be in the lens itself that could cause drastic underexposure....? Or am I missing something....?

Welcome any thoughts.

Did you try to take some photos on land with and without a flash?

Check the electronic contacts on the lens.

Yeah I did and it seemed to be fine. So Im wondering if the issue is with the lens and TTL? The lens works fine on its won, the issues with when I use RC TTL. So is there some issue with the lens and/or the contacts not transferring the TTL data to the camera (is that how it works?)

Looking at the contact points they seem perfect and clean.

Have you tried it with strobes in manual? Tested above water?

I’ve been an Olympus user for about 15 years. I have never been able to get their RC mode to work reliably and gave up on it completely. Try switching the camera to to fill flash and/or manual flash and leaving the strobes on TTL to see if anything changes

That’s weird to be caused by only one lens. It almost has to be a contact issue.

It is a weird one. Got me stumped. But yes, I'll try some variations of manual strobe firing.

Re RC - Ive had the opposite experience , works flawlessly every time for years.

But, in thinking about it, why would the lens impact exposure at all? I would assume the TTL reading is made by the camera not via the contacts on the lens? (and RC is via the hot shoe from the camera) And if it was a camera issue with TTL then it would happen on all my lenses instead of just this one...

To give the specific example of what I was doing:

• 50cm from the subject.

• 160/sec, f9, ISO auto (200).

• Both strobes fire.

• Image is near black.

I wondered if the problem is the camera taking the photo Before the strobes have fired?

But why would the camera do that only with this lens when all other settings are the same?

Mike, sounds like it's not syncing for some reason. To test sync see if you can put the camera in second curtain sync and take a test shot in dark room so the shutter speed is round 1 second. In second curtain sync the flash fires at the end of the exposure not the beginning, so in doing this you should see the pre-flash followed by the main flash if it is working correctly. The only reason to do this is to separate the pre and main flash so you can see them.

When you are doing this also check by looking into the lens that the aperture closes down when the photo is taken and compare the 9-18mm behaviour of when it stops down to your other lenses. You could also ask around to see if someone has one you can borrow to try.

Do you have an Olympus flash you put in the hotshoe, even the little accessory one? Or borrow one? Test the OM-5 and 9-18 with that to see if exposes correctly. If it does the same thing with the little accessory flash see if you can find a physical store with the 9-18 in stock and see if they will let you try another copy of the lens. Did you buy the lens new?

You can also call the OM service centre and talk to them, I found them quite helpful. For them to help though I suspect the problem would need to reproducible without the housing and your strobes involved.