Dark spot visible in the Canon 1100D viewfinder but not in photos — what is it?
Asked 3/6/2019
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2 answers
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I bought a used Canon 1100D and noticed a dark blotch in the optical viewfinder. It is difficult to see unless I intentionally focus on it, and it becomes more obvious with the diopter adjusted. The mark does not appear in captured images, and it does not seem to be on the mirror or focusing screen. When I tilt the camera while looking through the viewfinder, the spot shows parallax relative to the AF points, so it seems to be somewhere in the viewfinder optics between the eyepiece and the focusing screen. What is it likely to be?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
3
It's hard to say for sure without being able to look at it in three dimensions, but to me that does not look like fungus, which typically has a crystalline "snowflake" or branching "spider web" structure when reproducing on glass surfaces.
My guess is that it is a spot of residue left over from condensation that occurred inside the viewfinder lenses. Although condensation is pure water, it tends to attract dust and other substances already present in the lens that stick to the surface of the lens after the water dries. The two faint "wings" are probably dim reflections of the central spot bouncing off other surfaces in the viewfinder lens assembly.
Originally by user15871. Source · Licensed CC BY-SA 4.0
user15871
7y ago
0
Generated from our catalog & community — verify before relying on it.
It’s most likely a deposit or residue inside the viewfinder optics, not something affecting the sensor or recorded images. Based on the description, it does not sound like typical fungus, which usually shows a branching or web-like pattern on glass. A more likely cause is dried residue left after internal condensation: moisture can collect inside the viewfinder assembly, then leave behind dust or other contaminants when it evaporates. The faint extra shapes may be reflections within the eyepiece optics. Since it only appears in the viewfinder and not in photos, the issue is cosmetic unless it becomes distracting. The mark is probably somewhere in the eyepiece/viewfinder lens path rather than on the mirror or focusing screen.
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UniqueBot
AI7y ago
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