Thanks for all the info Brett!
Interesting update... I just had a go at adjusting the curtain tension ratchet for the first curtain. I tried at various click-stops and went as far as about 6 clicks to either direction and there didn't seem to be any change in what I saw through the back of the camera.
Soooo is it something different entirely? I'm not sure I want to do much more messing about than that. Looks like it's off for a service.
Looks like Michael Spencer has gone dark. I've requested an estimate from Luton, and Harrow Technical (I know he's the Pentax guy but I trust him) estimates £90 so we'll see.
It was definitely the first curtain ratchet you were adjusting? If so and it's had no effect, other possibilities might include a need to clean and lubricate the spindles or, possibly, deterioration of the curtains. Hard to know without taking a look inside of it. But from your description the first curtain is definitely running slow. Hence, if it's not insufficient spring tension, process of elimination suggests it has to be either lubricant/dirt related or mechanical (well, more "fabric" than "mechanical", Ie. stiff curtains?). But if the curtains are compromised, you should be able to tell easily enough. Usually they'd not sit perfectly flat, would be creased or wrinkled, and would be stiffer than normal (which is what would make them run slow). And you'd expect both curtains to be affected. Worth checking of course, just in case (old Exaktas, for example, are well known for having this problem, as are other former DDR cameras such as the Contax/Pentacon reflexes). But an OM-1 is not an Exakta, so I can't say, (not having worked on one yet), how prone the former is to this problem. Not as much as an Exakta, I should have thought. For the most part, Japanese curtains don't usually age too badly.
Trying the curtain tension was worth a shot because there are some focal plane cameras with springs that do not age well. Both of the Zeiss Icarexes I have featured springs that were badly weakened over time. One had a first curtain that would not even finish crossing the gate until it had been cleaned, oiled and the ratchet tension increased. Both are now running well and exposing evenly across the film gate so I can only assume the spring material or treatment was less than ideal. This is atypical and they're a lovely camera but a type I think are particularly prone to loss of tension, most are not so much.
What to do next, depends on whether you will have the camera dismantled and attended to. If you'd like to proceed further yourself, the first rule as always, is of course to do no harm.
If the curtains look and feel good, you could try placing very small amounts of naptha at the bearings for the spindles. You should be able to at least locate all four under the lower cover and hopefully, with the appropriate sized screwdriver, oiler or needle, to tease some directly down the shafts, after which the mechanism should be exercised a number of times. But please be mindful that you don't want trickles of naptha running amok inside the pentaprism and other areas of the camera body. This will only create more problems that may entail more expense to remedy. A drop only per 15-30 minutes per spindle please, and no more than three or four at most between cycling. If an improvement in the shutter accuracy is forthcoming after this, (even if temporary) you will have established the reason for the slow curtain travel and can proceed accordingly. Personally I'm inclined to think that it is a cleaning/lubrication issue, simply because the behaviour fits a slow first curtain so well, and, having boosted the tension without any improvement, another reason for its tardy progress across the gate has to exist. Given the age of the Olympus, I think it's the most likely cause.
Of course you may be inclined to refer the camera to a technician and that's perfectly fine, the above is mentioned only as a first step to doing a CLA yourself, which I'd anticipate would also dictate the removal of the top cover in order to reach the bearings at the other end of the spindles. If you're not prepared to do that, it's probably best simply to seek professional assistance.
😉
Cheers,
Brett
