The diamonds and bar graph are linked to the ASA setting (SV?), exposure
compensation (CV?), aperture (AV), and shutter speed dial (TV - only in
manual) through analog means. As far as I can see, there is no
hysteresis on the click dials, and they probably don't require it
because of the pseudo discrete steps. The aperture cannot have
hysteresis because it is meant to be a continuous scale.
So, the aperture input is analog (continuous scale) and the diamonds and
bar graph is a stepped scale. So you can move the aperture ring and find
a spot where the CPU will display the bar and diamonds in one place
after sampling the analog input (+noise), and then shift them one spot
after sampling the analog input (+noise) again.
When you get the diamonds and bar graph to shift to the right, grab the
aperture ring and move it a smidge to open the aperture up a little and
see if the diamonds jump back. Opposite if the diamonds have shifted to
the right.
I had the dancing diamonds conundrum with my OM4T and had a think about
it and came to the above conclusion. So I wouldn't worry about those.
What I am worried about in my OM4T is that the mirror keeps locking up.
I reckon RV409 needs adjustment. I haven't looked, but I suppose that
means a fair amount of dissassembly.
b k wrote:
> Hi everybody,
>
> First of all, thank you for your help ! I knew this list would be a good
> place to ask questions :-)
>
> Let me give you a few more details about my camera and its problems. I think
> there is an OM-4t circuit inside - battery drain is low, and in "battery
> check" mode the beeper stops after 30 seconds. I guess it means that the
> meter should not be as "jumpy" as the ones with earlier versions of the
> circuit, right ? In my case, when metering in a sunlight, there always is one
> meter bar blinking, and sometimes two. In an artificial light, especially
> fluorescent one, it gets much worse. Same thing happens when metering in spot
> mode - the diamond usually oscillates between two, and sometimes three
> neighboring positions.
>
> But, the problem I originally described in point 2 is different. I was
> referring to measurements that had already been made. Let's assume that I
> have already pressed the SPOT button several times, and several diamonds are
> lit. The one that represents current spot value will obviously move if I move
> the camera, or oscillate as described earlier. But, diamonds representing
> previous measurements should stay where they are, right ? In my case, they do
> not. Sometimes the entire set moves to the left or right, or starts
> oscillating. This is very erratic and does not happen all the time.
>
> The problem described in point 3 is very consistent and can be reliably
> reproduced for certain film speed / compensation settings. I managed to take
> a few shots with a web cam to illustrate it better. Have a look here:
> http://www.geocities.com/brtlmj/om-4.html
> The first photo shows the situation with four spot measurements made and no
> compensation. Indicated shutter speed is 1/30s. Then I used exposure
> compensation: -1/3, -2/3 and -1 EV. As you can see on the next three photos,
> the shutter speed increased first to 1/30+1/3, then to 1/30+2/3, and the
> remained at 1/30+2/3, but... all four diamonds moved to the right. Strange,
> isn't it ? I checked it the ASA dial moves when I use the compensation dial,
> but it does not.
>
> I am getting convinced that something is wrong with the camera, but want to
> make sure that I am not unreasonable before I send it back. On the other
> hand, I definitely want to get all I am entitled for, especially taking into
> account than an OM-4 overhaul costs about twice as much in Europe as it does
> in the US...
>
> A question for Clint and John: would you ship a camera that behaves like this
> one back to a customer as "overhauled" ?
>
> Thanks !
>
> Bartek.
>
>
>
>
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