photography question

[dakegra]

imagine the scene, if you will.

I'm taking a photograph of a framed mirror, about three feet away. I want the frame in focus. I set the lens to focus at 3 feet, and take the photo. I've got a really narrow depth of field, so *only* the frame is in focus and not the background etc.

If I then want to take a photograph of *myself* reflected in the mirror, would I need to adjust the focus? Or would I need to set the focus to six feet?

I'm sure there answer should be obvious, but it's been noodling around in my head for a couple of days now, and I realised that one of you lot would be able to answer it.

Comments

[anonymous-greg.livejournal.com]

Six feet. Remember: You are taking a picture of light. The light travels from you to the mirror (3 feet), then back to the camera (another 3 feet), for a total of 6 feet.

[songster.livejournal.com]

What he said. The image isn't "on" the mirror, it's behind the mirror. When you take a photo of something through a window, you focus on the something, not on the window glass. Same applies to mirrors.

[anonymous-greg.livejournal.com]

Ooo, I like that "behind the mirror" description. Likening it to a window is a fabulous analogy. I'll be using that the next time the question comes up.

[dakegra.livejournal.com]

me too - that's a great way of describing it.