It's reasonable to consider reproduction ratios in approximately the  
1:4 to 2:1 range as "macro" despite more specific definitions for  
photomacography and microphotography.

Most lenses marked as Macro achieve 1:4 to 1:2 magnification ratio  
without additional equipment. Some go to 1:1. For instance, the smc  
Pentax-A 50mm f/2.8 Macro is a superb performer and achieves infinity  
to 1:2 magnification without additional extension.

Godfrey

On Apr 29, 2007, at 8:10 PM, Adam Maas wrote:

> Macro is in the 1:2 to 1:1 range. Your Tamron does 1:2 (half life- 
> size)
> without the dedicated extension tube.
>
> Microphotography is greater than 1:1 magnification. But that generally
> requires bellows or a reverse mounted lens on a macro lens rather than
> just a macro lens.
>
> -Adam
>
> Jens Bladt wrote:
>>  I have photographed my Stanley measuring device with a
>> Pentax K10D and a Tamron SP 2.5/90mm lens - at closest possible  
>> focusing
>> distance; 0.39 m. Is this macro?
>> http://www.flickr.com/photos/bladt/477746425/
>>
>> Maybe not. My sensor is 23.5mm. This image covers appr. 47mm. This  
>> means
>> it's almost accurately half natural size - 50% on the sensor.
>> Isn't macro photography supposed to be enlarging the subject?
>> On a computer screen my 3872 pixel would look like 1366 mm. That's an
>> enlarement of appr. 2900% (almost 30 times).
>> But enlarging the copies (negs) is not really macro, is it?


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