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[OM] Anomalies in E-1/OM Images -- Update

Subject: [OM] Anomalies in E-1/OM Images -- Update
From: Cyrtolite@xxxxxxx
Date: Wed, 12 May 2004 08:04:34 -0400
Following up on advice from Winsor and others, I took a few shots of the sky 
with the E-1 using the 14-54 at f22, and again, using the OM 65-200 at f32.  I 
ran auto levels on the images and sharpened them a bit.  I first took three 
shots with the 14-54 on 5/10 and then, after examining those, I did some more, 
using the 14-54 and 65-200, on 5/11.  

1.  Some of the concentric-ringed spots that first appeared in my bellows 
images are very, very faintly visible in the 14-54 images but, if I hadn’t 
known what to look for and exactly where in the image to look, I might very 
well have missed them.  They are a bit more visible in the OM 65-200 images but 
still pretty inconspicuous – not nearly as conspicuous as in the bellows shots. 
They are completely invisible in all images until the I run auto levels, which, 
in a blank sky picture, increases contrast well beyond reason.  I tried to find 
the contrast level at which the spots become visible and it seems to be between 
about 50% and 75% on Photoshop’s contrast slider.

2.  A couple of the first images exhibited small specs that did look like dust. 
 Interestingly, their locations varied from image to image, suggesting that 
perhaps the shutter action was moving them. Before taking additional shots on 
5/11, I faced the camera down and turned it on to loosen any dust using the 
E-1’s sensor cleaning mechanism. I then set the shutter speed to 2 seconds and 
took a couple of exposures with the camera still facing downward and removed 
the lens. This, I thought, would allow any loose dust particles in the chamber 
to escape.  I repeated this process a couple of times.

3.  The images I took on 5/11 with the 14-54 and with the 65-200 still had the 
very faint concentric-ringed spots in the same locations, but no sign of dust.

I conclude from this that the concentric-ringed spots are caused by something 
on the sensor but it is not dust.  I am not concerned about them because they 
are not affecting image quality, especially when I use the Zuiko Digital 
lenses. I continue to be amazed and very pleased with the images the E-1 is 
producing regardless of the optics I attach.


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