gdanmitchell Offline Upload & Sell: Off
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My first thought was "hot pixel." It presents virtually all of the symptoms: a primary color (either red, blue, or green), in the same spot in every photograph, etc.
The one confusing thing, though, is that if we are looking at a 100% magnification crop the pixel should occupy exactly one pixel in the image — but this one seems larger and longer in the vertical direction. That seems a bit more like an optical thing, especially if it is near the edge of the frame.
To make sure, make an exposure in raw mode, perhaps shooting a monochromatic, featureless subject, and then look at the file in your raw converter without applying any sharpening or other post-processing. If that turns this into a single-pixel artifact, you have a hot pixel.
Normally, most raw conversion software (and certainly that from Adobe) will map out these pixels and you'll never notice them again. I don't know what the current policy is, but it has always been the case that manufacturers (of sensors, computer screens, etc.) set a certain maximum number of acceptable bad pixels, below which they won't replace the unit. If so, make sure that you are set up to have your post-processing software manage it and you'll be fine.
One more thing. Underexposing high ISO exposures can make such similar noise issues more visible. I didn't check your file, but could this play a part?
Dan
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