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Old Sep 22, 2008, 12:50 PM   #1
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ok just about all digital camera's have the macro setting on the camera, but looking on ebay for a macro lens i had a question. what makes a lens a macro lens? some of the lens i looked at were 24-85mm, 35-70mm, 105mm.

people are advertising them as "great for portraits, close-ups of flowers and bugs"

can a macro lens then be used for a regular lens then?

and if you press macro button on the camera with a 55-200mm zoom its now a macro lens???


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Old Sep 22, 2008, 3:02 PM   #2
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You seem to be discussing a DSLR and macro lenses so I will answer to that.

A macro lens on a DSLR can usually focus from infinity to close enough that the image on the sensor is from half life size (1:2) to life size (1:1). So at 1:1 I would be able to photograph a rectangle the size of my camera sensor at minimum focus. It can also be used as a ordinary lens in general photography.

The macro program setting will try and set up the aperture and shutter speed to get the best results when shooting macro. It would be pointless to set it if you aren't using a macro capable lens.

Real macro lenses are fixed focal length and have excellent image quality. Some third party zoom lenses are labeled "macro" and can focus down to 1:2 as a rule but should really be considered "macro-like" in terms of quality.
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Old Sep 22, 2008, 3:10 PM   #3
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The 'Textbook' definition of 'Macro' is when the image projected onto the sensor is life-size. That's the 1:1 magnification that you will often see. That is frequently relaxed to 1:2, where the subject is 1/2 life-size on the image sensor.

But the generic term 'Macro' as it appears in advertising literature, simply means 'close focusing' with as little as 1:4 magnification (and maybe less.)

But, of course, cropping and/or enlarging high resolution images makes the whole issue practically moot, IMHO.
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Old Sep 22, 2008, 5:45 PM   #4
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TCav wrote:
But, of course, cropping and/or enlarging high resolution images makes the whole issue practically moot, IMHO.
The rest I agree with - but not this last statement. Simply take a look at photos in the forums where people are using 1:4 macro lenses - then look at the macro shots by people using true macro lenses. There is a huge difference in quality. You can't crop your way to detail. And in macro photography, it's all about the detail. Assuming there is detail there. For instance an insect has a LOT more detail than a flower petal. So it really depends on the subject matter.
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