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DSLR’s and Macro- Sensor Reflection Problem
By sirsnapalot | February 24, 2010
Since I’ve been doing extreme macro lately, I’ve run into a perplexing problem. In some cases, I see a magenta-tinted dot in the center of my images. I knew it was related to the lenses, but did not know specifically what was causing it- thinking it was an internal issue to the lenses. I also noticed in some cases it was less noticeable than others.
Sensor Reflection
In this picture, you can see it clearly. While most of the time it is not this vivid, I chose this shot to highlight the issue.
In a DSLR, the CCD (image array) has a much shinier surface than did film in older cameras. As an image falls onto the sensor array, some of it is reflected back to the lens, and some of that can reflect again back down to the sensor. In lenses made for DSLRs, they have anti-reflective coatings to minimize the problem. But with older lenses, such as I am using here (this was taken with an old Canon FD-mount lens), the coating is missing and this can be a problem.
In this particular shot- a poppy seed, I have the seed sitting on an illuminated background- probably the worst situation. Likely, a darker background and diffuse side lighting would be best. I’ll need to experiment to learn how to minimize this, and will post results when I do. Needless to say, however, when you push your equipment to the limits, you run into issues where you must tightly control the situation, or make compromises.
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Topics: Advanced, Macro, Technique | No Comments »
