OM4Ti will only fire at 1/60 in auto mode.

[Johnmcd]

Hi,

Just received an OM4Ti in good condition and put the first film through it. All the images are over exposed significantly. I had sensed that it sounded slower than what the speed indicator was saying in the VF. I then did a couple of tests against another camera and found the following:

1. The meter is 'showing' the right speed in Auto (AE) with centre weighted metering.
2. But the camera always fires regardless, at what I would guess was 1/60 sec.
3. In spot exposure mode it also shows the correct speed and actually fires at the correct speed. So it seems that the problem is only when on Auto without spot metering.
4. In manual mode the camera seems to fire correctly at all speeds.

Any ideas?

Cheers - John

 

[Mark Wood]

Apologies, as this reply won't be a lot of help but that all sounds pretty much identical to the problems I had with a standard OM-4 a couple of years ago. Interestingly though, that one behaved in exactly the same way as you're describing with the film speed set to 400 ASA but it seemed to work normally at 100 ASA. It took three trips to a specialist Olympus repairer in the UK to finally get it sorted out but I never did find out exactly what the problem was from them. All I do know is that on the second trip, they replaced the film speed setting dial with one from an OM-4Ti. (Given that the OM-4 still does drain batteries quickly, I'm pretty sure it hasn't been upgraded to more OM-4Ti circuitry at any point in its past.)

Just in anticipation of any comments about needing film installed to give the same shutter speed as the one indicated in automatic mode, that wasn't the issue. Even with the indicated speed being 1 second (where it would have given several seconds with no film in the camera), the shutter was still firing at about 1/60th.

 

[Johnmcd]

Very interesting. My film speed was 800.

The plot thickens. I just changed it to 100 ASA and it stopped just doing 1/60th but now 1/8 is about 3 seconds! All the slower speeds are way too slow (seconds). 400 ASA is all over the shops as well.

Definitely something to do with ASA selection. That said it seems fine if i select spot metering.

Thanks. I would say this is a similar problem.

 

[Mark Wood]

Yes, my OM-4 was working fine in spot metering mode too.

With no film in the camera in automatic mode, an indicated 1/8th second will give a noticeably longer shutter speed, as the camera is metering with light reflected off the black pressure plate when it makes the actual exposure. 3 seconds is probably about right.

 

[Chriscrawfordphoto]

Yes, my OM-4 was working fine in spot metering mode too.

With no film in the camera in automatic mode, an indicated 1/8th second will give a noticeably longer shutter speed, as the camera is metering with light reflected off the black pressure plate when it makes the actual exposure. 3 seconds is probably about right.

Mark is right. In non-spot Auto Mode, the OM-4T (like all Olympus SLRs that offer autoexposure) meters off the film. When no film is in the camera, instead of seeing film, it sees the black pressure plate, and thinks there is not much light and overexposes. You will get correct exposure with film in the camera.

In spot mode, the camera does not meter off the film, so it is not fooled by the dark pressure plate when no film is in the camera.

So..try it with film; I bet it'll work just fine

 

[p.giannakis]

Put a piece of silver foil in the film chamber and see if this affects exposure. OTF metering works up to 1/45 sec I think. Past that it reads exposure from the first shutter curtain ( the OM2 does so, but i think the OM4 is the same).

 

[Johnmcd]

Thanks for all the help.

It came with a small thin piece of near translucent plastic that sits where the film would be. It states it should be inserted for 'demonstration purposes'. I assume this is to trick the OTF. Nevertheless, with that inserted, the auto metering is accurate in the VF but the shutter when it actuates, is never faster than about 1/60.

 

[Johnmcd]

I'm sitting here banging away, comparing auto against spot and the shutter speeds which are comparable in the VF, are all over the place in auto and not even consistent if I repeat without changing what it is metering off. Even if the OTF is making things difficult, it should at least be consistent.

There is definitely something weird going on.

 

[Sarcophilus Harrisii]

Very long shot John but is the ring for the aperture position moving correctly? I have no idea but if it happened to be stuck on say f/16 or f/22 that would keep the shutter speed well down compared to what it would otherwise be with a lens opened...
https://www.rangefinderforum.com/classics/forum/messages/15681/11247.html?1200555001

It's so obvious I hesitate to even suggest it, but your battery is definitively good? If you have a multi-meter handy it never hurts to do a quick check, even new ones have occasionally known to be bad.
Was thinking of you the other day and wondering how you and the Z are travelling. 😉
Cheers,
Brett

 

[David Hughes]

Just a thought, the switch on the left takes you between spot, manual, auto etc and might just be dirty? So mechanicals and not electronics, perhaps.

I've had minor problems with these switches on other OM's but don't have a 4Ti so I'm just guessing.


Regards, David

 

[jajong]

Does it have a black painted battery cap? They were famous for bad electrical connection and consequently erratic behaviour of the camera.
Cheers,
Jan

 

[Johnmcd]

Does it have a black painted battery cap? They were famous for bad electrical connection and consequently erratic behaviour of the camera.
Cheers,
Jan

No the battery cover is silver. Cheers.

 

[Johnmcd]

Just a thought, the switch on the left takes you between spot, manual, auto etc and might just be dirty? So mechanicals and not electronics, perhaps.

I've had minor problems with these switches on other OM's but don't have a 4Ti so I'm just guessing.


Regards, David

Thanks David, but I don't think this is the problem. The spot is actuated on the right near the shutter button and works separately.

 

[Johnmcd]

Very long shot John but is the ring for the aperture position moving correctly? I have no idea but if it happened to be stuck on say f/16 or f/22 that would keep the shutter speed well down compared to what it would otherwise be with a lens opened...
https://www.rangefinderforum.com/classics/forum/messages/15681/11247.html?1200555001

It's so obvious I hesitate to even suggest it, but your battery is definitively good? If you have a multi-meter handy it never hurts to do a quick check, even new ones have occasionally known to be bad.
Was thinking of you the other day and wondering how you and the Z are travelling. 😉
Cheers,
Brett

Hi Brett. I replaced the batteries with new ones and no luck. It is definitely erratic in auto with no rhyme or reason regardless of the ASA.

The Z is doing very well as I had a full top end rebuild completed recently by Surfside Motorcycles at Manly. Just 'running' it in at the moment. Get the valves checked at 1000 k's or so.

John

 

[jajong]

I found an article about chasing OM-4 electrical gremlins. It suggests that erratic behaviour is caused by dirty wipers under the ASA knob. So a clean or operating the knob for a period of time may help. I 'll send you the article via PM, if possible.
Cheers
Jan

 

[Johnmcd]

I found an article about chasing OM-4 electrical gremlins. It suggests that erratic behaviour is caused by dirty wipers under the ASA knob. So a clean or operating the knob for a period of time may help. I 'll send you the article via PM, if possible.
Cheers
Jan[/QUOTE

Thanks for the info Jan. Please PM me.

Cheers - John

 

[jajong]

Hi John, I PMed you yesterday. The forum email doesn't allow pdf attachments.
So please PM a regular email address, and I will send the article.

Cheers,
Jan

 

[David Hughes]

Thanks David, but I don't think this is the problem. The spot is actuated on the right near the shutter button and works separately.

Hi,

I suggested the switch as it was the obvious mechanical link in the train and the spot button and film speed switch are the same. So I'm still betting on a bit of dirt to cause a HR. Especially in view of the low level of power needed in those electronics and the comparative HR of a bit of dirt. (EDIT) Sorry HR is high resistance, force of habit; like NFF (No Fault Found).

Anyway, I'll wish you luck.


Regards, David