Om4 woes

[Paul Green]

I have had my om4 for about 7 years, but for the last 2 years I have not used it often, other than playing with the lenses to keep them lubed.

I got it out today put some fresh batteries in, shot a few frames and noticed that the shutters speeds were sluggish sometimes and then it would go back to normal.
After trying some other batteries and lens combinations I found that the problem didn’t happen in manual mode or AP when a spot meter was taken, so it only happens in AP mode.
Also worth noting is that when in AP with the back open the shutter speeds seem fine.

I am assuming that it’s something to do with the light meter or something electrical. I am happy to shoot in manual or AP using the spot meter, it's just a bit annoying

 

[mopar_guy]

Make sure to use Silver Oxide batteries, alkaline batteries can cause problems.

 

[Les Sarile]

To be sure, all speeds - except for B & 1/60, are electronically timed and therefore based on what it senses OTF - off the film plane. Without film, the OTF sensor only sees the black pressure plate and gets a "darker" reading then if film where in it. With the back open, the the shutter fires faster with the light coming in from the back.

In manual mode, the OTF reading is on that pattern you see behind the mirror.

 

[Les Sarile]

Next only to Pentax LX in EV range but I prefer it because of the spot mode - don't need nor use the shadows or highlights function. Both the OM-4T and the LX will constantly monitor the scene for light change and will alter exposure time accordingly. I've successfully metered exposures to an hour with either as they are the best even compared to today's latest and greatest.

 

[Bill Burk]

Check the +/- indicator. It is very possible that the contacts on the ASA/compensation dial have become dirty and are causing several stops compensation because of electronic contact. Working both dials back and forth has worked for me before to resolve this issue.

 

[Les Sarile]

BTW, if it turns out there is something wrong with your OM-4, I am seeing some recommendations for Camtech Photo Services, Inc located in NY. I have not had to use them myself but am keeping tabs on reported good service places for my classics.

 

[chriscrawfordphoto]

John Hermanson, the owner of Camtech, is an APUG member. He is the best OM tech in the USA, a former Olympus service manager. He's repaired gear for me

 

[Bill Burk]

ps when it was the +/- or ASA dial for me, the shutter speed displayed in the viewfinder agreed with the shutter speed I was hearing.

 

[Bill Burk]

pps Les is right, you have to put film in because of the real-time off-the-film metering.

 

[Paul Green]

Thank you for your replies guys, I understand how the OTF metering works, but what has me confused is that I have been testing it on a tripod pointed at the same light source and the shutter speeds seem to range drastically once the shutter is pressed. I will put a roll through it this week and see if I am just being silly.

 

[mopar_guy]

When these cameras were new, they shipped with a piece of gray cardboard that covered the pressure plate. They will not meter the correct value in Auto mode without film loaded or without this cardboard in place. See this recent thread:

(there was a url link here which no longer exists)

 

[John Hermanson]

Your OM-4 may need service, but as mentioned, film (or test card) must be loaded and a lens mounted for auto speeds to be correct. John

 

[Pumalite]

There was history of the OM-4 and batteries, but by now every camera has been corrected for sure. It wouldn't hurt to check though. (CLA)

 

[k_jupiter]

What is amazing is I knew the answer when I read the question... it needs film to work correctly because of the OTF metering.... And I have never owned a an OMx.

The mind is a strange place where you pick up information from decades ago and it pops up in the strangest places.

tim in san jose

 

[RH Designs]

My OM-2SP has a dodgy ISO control meaning the shutter speeds will vary from time to time. If you watch the exposure time indicator in the VF and touch the dial, you can see it change. Might be worth trying the same on your OM-4 to see whether that's the culprit. Also check the battery compartment cover is spotlessly clean and properly seated as that can cause connection problems and result in odd behaviour. I have an OM-4ti which squeaked and misbehaved when squeezed or twisted - like I was hurting it! I traced that to the connection between the body and the base cover which relies only on the metal-to-metal contact, there's no wire. Cleaning both seating surfaces pretty much cured the problem.

 

[John Hermanson]

In manual mode, the OTF reading is on that pattern you see behind the mirror.

In manual and auto, meter reading is taken through the mirror, reflected by the sub-mirror, down to the cell in the floor. Pattern on curtain is used when in auto - otf mode. John