Life Size vs. Half Life Size Macro: How Big Is the Difference?

Should I buy a 1:1 (life size) or a 1:2 (half life size) macro lens? That's a common question asked by many a beginning macro photographer. The problem: life size is the now standard spec for current macro lenses but old, half life size models from the beginning of the AF era (or even the MF era for that matter) can be had for a fraction of the cost of a modern macro.

So, how big is the difference? Well, look below to see.

As you can see, the difference between life and half life size (not to mention double life size) is very noticeable indeed, with the life size quarter appearing to be about 4 times bigger than the half life size one. As for why the huge difference, it is thanks to the fact that the image is a 2 dimensional object and, by shrinking each axis by a factor of 2, you get a total shrinkage of a factor of 4 (½ x ½ = ¼).

Now, that's quite a loss but there are two ways around the problem: cropping in Photoshop or extension tubes.

As you can see on the above picture, I could easily just crop the half life size image to be the equal of the life size one. Unfortunately, by doing this, I would be eliminating ¾ of the original image's resolution in the process, which presents another problem: can I afford to lose 75% of my pixels.

For 99% of people reading this, the answer is 'yes!'

Modern dSLR cameras have insane resolutions of at least 16Mp, which is way, way more than most people will ever need. Take it from someone who has been doing this since high school: you don't need massive pixel counts to get great prints. In high school, we were sometimes using 3Mp images (state of the art in the early 2000s) to fill 11x14 pages. Result: they looked great!

Don't print? No problem as all affordable computer and TV screens are 1920x1080 pixels in resolution, which translates to a measly 2Mp, which is half of the 4Mp you would get by cropping a 16Mp half life size image to the equivalent of a life size one. Bottom line: whether you show off your images on screen or on paper, you'll have plenty of resolution to send your audience members' jaws dropping to the floor provided you know how to shoot macro. 

 

Work around #2: extension tubes.

 

For anyone in the know, extension tubes are merely lens accessories without glass that mount to the rear of a lens, extending the lens and increasing the magnifying effect. Whatever your make, extension tubes can be had from manufacturers or third parties, thus making it easy to boost the native magnification power of a lens, whether that lens has a native magnification factor of 1:2 or 1:1.  

See also: Macro Photography Primer

My advice: save the cash, buy the 1:2 lens, and crop your pictures or buy extension tubes if you must need to keep all your pixels. After all, money doesn't grow on trees.

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