I once had a focus problem with an OMG which caused 1/3 to 1/4 of prints to
be way out-of-focus. T urns out it was a "light box out of alignment,
unfixable". I assume by "light box" they meant the structure inside, below
the focus screen, to which the mirror is attached. Fortuneatly, I had a
donor OMG available for swap/fix.
Gary H.
----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Saturday, August 27, 2005 4:38 PM
Subject: [OM] Re : Constructive criticism wanted...
> Philip Pemberton wrote:
>
>>Hi,
>> I've just got my holiday photos back, and I've noticed a bit of a
>> problem
>>on most of the negatives.
>> All of the photos I took where the subject was between 4m and 10m away
>> are
>>hopelessly out of focus, even though they appeared to be perfectly in
>>focus
>>in the viewfinder. I didn't use the prism or "image slicer" focus aids,
>>because they don't seem to work very well on my OM10 for some reason
>>(especially in very light/very dark conditions). Aperture was full-open
>>(f1.8
>>for the shots taken with my Zuiko 50mm, f4 for the ones I did with the
>>Tokina
>>80-200) due to low light conditions. Most of the time, the exposure
>>metering
>>came up with stupid figures (1/250 in the middle of a dark woodland area,
>>I
>>think not) so I set the camera on 1/60. Camera is an Olympus OM-10 with
>>Winder 2 (I want an OM2sp!).
>>
>>
> So I assume you already know your exposure meter is wonky. One possible
> cause of focus trouble that's apparent only at wider apertures is a
> mirror that is out of adjustment. DOF can mask the problem at smaller
> apertures.
>
>>I've uploaded some of the photos to
>><http://www.philpem.castlecore.com/gallery/> (in the Scotland album), with
>>more to come just as soon as my Epson 2400 scans them and I tweak the
>>colour correction a little. I really do need to get a negative scanner,
>>but I've been promising myself an OM2sp for ages... hm... decisions,
>>decisions. IMHO, 07A is probably the worst and 16A is probably somewhere
>>near the best. Or rather it would have been if it were a little lighter,
>>but that's more or less what it looked like in real life...
>>
> However, I don't think the mirror is the problem here, because focus is
> missed in both directions. In 07a, the plane of focus is behind the
> subject, with nice sharp foliage behind a fuzzy tree/box. In 10a, the
> subject is still oof, but the stuff behind it is even fuzzier and the
> green leaves in the sun are more in focus. So I must conclude that focus
> was missed in opposite directions in the two shots. 12a looks like is is
> focused just a bit behind the subject, with the branches immediately
> behind the tree at least close to in focus. 13a looks like the front of
> the tree itself is in focus, but the box isn't quite sharp. Very close
> to correct focus. 15a is focused a little further behind again, close to
> 12a. 16a may be better than 13a, but it's so dark who can tell.
>
> You say you avoid using the split image focus aid. Do you simply focus
> on something outside the aids while keeping the framing you want to
> shoot? If so, you may be focusing on something at a different distance
> from the camera than the subject. At f1.8 and 50mm or f4 and a longer
> fl, that's not going to work because of the shallow DOF. I can see how
> it would be difficult to focus on the subject here in dim light and
> easier to focus on the clearer, back lit detail of its surroundings.
> Those visually surrounding objects are all behind teh subject all but
> one shot are focused behind the subject. If your main subject is in the
> center and you want to use the matte area to focus, you need to get the
> subject out from under the focusing aids, focus, reframe and shoot.
>
> With a some of sharp edges on the box, I would think the split image aid
> would work properly here. I suggest some tests with a cheap roll of
> film. Try focusing on something with split image, take a wide open pic,
> note the distance on the lens scale, then try slightly different focus
> settings in both directions. Then do the same thing focusing using the
> matte area. Keep careful notes, or it will all be a muddle when you get
> the results back. That should determine whether one or the other or both
> are accurate and, if not, in which direction the inaccuracy goes.
>
> If the results show a problem with focus in the camera, replacement is
> probably better than repair, with an OM-10. If the results show that the
> focus is accurate in good light with a target selected to be easy, then
> the problem is in your focusing technique in the field and an OM-2sp
> will have the same problem. If the tests show that the focusing aids can
> be relied on for accurate focus, you can use them in difficult
> situations like the samples you posted. It's really hard to accurately
> focus on the matte surface in very low light.
>
> Moose
>
>
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