The 2S, 3, #Ti, 4T/Ti have a curtain speed adjustment that is different
that OM-1 thru 2N. Yes, adjustment screw head is in the bottom, but the
notched nut with locking spring is at the other end (top) of the camera,
buried under the circuit board. If the screw head at the bottom is
pushed a little too hard, the notched nut at the top can separate from
the locking spring and cause the curtain spring to unwind. oh
boy.............
___________________________________
John Hermanson | CPS, Inc.
21 South Ln., Huntington NY 11743
631-424-2121 | www.zuiko.com
Olympus OM Service since 1977
Gallery: www.zuiko.com/album/index.html
WayneS wrote:
> I used a laser pointer and a photo transistor. I actually found that
> some old transistors in a can worked the best. I cut the top off.
> The transistor was a gain stage with an emitter follower.
> If the OM archives are around, I probably discussed this.
> Here is the original board I used, which I just happened
> across last month while cleaning the basement.
> http://www.zuik.net/OM-4t/shuter_test_MG_6132.jpg
> I'm surprised I still have it.
>
> The laser pointer, aimed at the transistor, made for sharper
> transitions when the shutter passed. So, once I had the pointer
> adjusted, I would put the camera in the path, and first test the
> start of the shutter curtains, then the end, and compare the
> pulse widths. The pulse width at 1/2000 would measure
> the shutter speed, while testing the pulse width at the
> start and end, would check for uniform travel speed of
> the two curtains. There are two tension adjustments
> you can access by removing the bottom plate.
> (Obviously this testing is done with the lens and
> camera back removed.)
>
> But I highly recommend sending the camera to John H for
> adjustment, as he is the pro and there is more to it than
> just tweaking these two tensions. The shutter release
> really needs to be cleaned before doing this adjustment.
>
> The curtain travel accelerates, so the rise times are faster
> at the end of the travel. I used to get quite a few cameras
> from eckBay and would test them, as well as OM-2n's and
> OM-1's. A good OM-4t would be less than 25% off at 1/2000.
> Fortunately that speed is rarely used. Sometimes the curtains
> would be completely closed by the end of travel, one catching
> up to the other.
>
> You would be surprised how often this speed is off.
> You can also test by taking a picture at 1/2000 and checking
> for exposure accuracy and uniform exposure.
>
> A brand new Leica M6 at 1/1000 was off by a lot more,
> which I returned for a second one, which was also off.
> So I passed on using Leica cameras. The OM's in my
> opinion had better accuracy, which they would
> have to to get 1/2000 speed.
>
> I tried a number of circuits, and this worked the best. It takes
> a bit of tweaking to get the response right. I bet the transistor
> I used was made in the 70's.
>
> WayneS - OM geek for the day
>
> At 09:49 PM 12/20/2008, you wrote:
>> Wayne, I'm most interested in how you did so.
>>
>> Perhaps you're willing to tell me about this, whether on or offlist, as
>> you judge better.
>>
>> TIA
>>
>> Fernando.
>>
>> WayneS wrote:
>>> I used to check the shutter travel time. The OM-4t weakness is
>>> at 1/2000, where exposure variation across the frame is most likely.
>
>
>
>
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