Wats wid Macro Mode

[Vaibhav]

Hi guys,

This question has been bugging me for a long time now. I own a Canon 710IS. There is a macro mode availablei n the camera.
Can somebody help me understand how macro mode is different from using manual focus to focus at close subjects? Also if someone can throw lite on the optical physics behind the macro mode if any, i will be grateful?

Regards
Vaibhav

[wulf]

Off the top of my head, I can't tell you the details of the physics (Wikipedia would probably be a good starting point) but the difference is that macro mode lets you focus closer. That's a fuzzy answer because different cameras and lenses will have different parameters.

Macro is more often defined by the relation of the size of the object to how it is represented on the camera's sensor. If the object measures 1cm and takes up 2/5ths of the width of the 2.5cm sensor in your camera (sharply focused), you have reached "true macro" with a ratio of 1:1. Many lenses that boast macro only actually allow 1:2 or less although this is still close enough to create some stunning images and is generally accepted as "macro" by all but the purists.

On a point and shoot camera, I suspect that it also narrows the aperture as a wide aperture gives very narrow depth of field at those distances. I used to abuse this to give me a slower shutter speed on my old camera; on my DSLR I rejoice in the control I have over all the options.

Wulf

[rdaw]

I asked this question in a few other forums a long time ago, and the only response I got was that macro would probably stop things down somewhat to increase DOF - my intent was to go out and test it: compose a close-focus manual shot, note my settings then see what settings macro mode came up with, but that's another of those things I never got around to....