I have a 4 month old D5100 and just noticed this problem. One night, I setup on a tripod and took pictures of the moonlight. All pictures had some kind of a "second moon" - clearly a reflection, but at different spots in each picture. I tried with different lenses, same effect, so it is not with the lens. I can see the reflection at the same spot in the view finder as the actual picture, if that helps identify the problem. I tried to take pictures of a glowing light bulb and the issue reproduces every time. I don't see any problems if I do not focus on the bulb. I have tried a sensor clean (it is also set to clean the sensor on start-up/shut-down), but no use.
Is this a problem with the sensor or just dust or water?. Should I send it back to the store or is there any other way around this? Any advice will be helpful. If it is just dust, how to get it cleaned? If it is water, is there any way to get it out?
Do you have UV filters on your lenses? Any cheap(ish) filters will cause these when pointed at bright light with a dark background. They are always a direct reflection from the center if the image, which all of these examples show.
They are internal reflections, off back surfaces of lens elements. Notice that they appear opposite the light source, for example if the source is toward upper right of center, the ghost image is toward lower left. UV filters, especially those that are uncoated or only coated on the forward-facing side, are a culprit, but some lenses are worse than others as well.
Do you have UV filters on your lenses? Any cheap(ish) filters will cause these when pointed at bright light with a dark background. They are always a direct reflection from the center if the image, which all of these examples show.
This is not an issue with the filters. I get the same issue without any filters.
