Macro lens vs a regular lens

[Galiven]

Very new to dSLR and this is probably a stupid question, but here it goes anyway. What is the difference between a macro lens and a regular prime lens?

I'm just starting to get the hang of what all the lettering and numbering for Canon lens' mean (EF vs EF-S, ULM, IS, etc ...) but I still haven't grasped this whole macro deal. I know that macro photography is taking pics of small items or getting extreme close-ups to the subject but how an EF 50mm f/1.8 lens is different from an EF 50mm f/2.5 Compact-Macro eludes me. (size, aperture difference, and price aside that is) Is it simply that the macro lens can focus on subjects much closer than the regular 50mm? I appreciate any info you folks can provide. Thanks.

[Palladius]

As far as I know, a macro lens is one that can form a focused image of an object on the sensor or film that is the same size, or larger, as the the object itself.

So, practically, I think, it comes down to how close it can focus....

[OsmosisStudios]

Macro lenses are able to focus close enough that they can reproduce the subject at a 1:1 ratio on the sensor.

Lets say, for isntance, that you're shooting the head of a nail that is 7mm across. With a non-macro lens, you'll get a picture but it might not necessarilly be exactly the same size. With a macro lens, everything is to scale and your nail head will be 7mm across.

This is all you need to know:

Macro > Anything

[OsmosisStudios]

Originally Posted by maxharvard

This is all you need to know:

Macro > Anything

How did you come to this? It makes literally NO sense.

[Galiven]

Thanks for the replies guys. Makes a bit more sense now. I guess my confusion really lies in that I've seem some great macro photo's posted on this using the regular 50mm lens and never really had an eye for whether the photo's subject was to scale. I'll try to keep an eye for scale in the future to see if I notice the difference.

Originally Posted by OsmosisStudios

How did you come to this? It makes literally NO sense.

I'm guessing he just really like macro photography?

So I guess the next question is can a macro lens still be used like a prime for taking regular (non-macro I guess?) photo's? Are they limited in any way or are they just special in that they are better at capturing small targets and maintaining scale?

[inkista]

Yes, the only difference between a macro lens and a regular prime lens is that it can focus closely. In terms of the design of the lens, this usually means incorporating a "floating" element/group, which is not the norm for other lenses. An element is a piece of glass in your lens. Most photography lenses have a bunch of them, arranged into groups. Typically, within a group, the elements correct each other, which is why the specs will tell you how many elements are arranged in how many groups.

A floating element/group can shift its position, depending on where the focus is set. This makes the lens capable of close focusing, and is also what makes macros the sharpest lenses in ANY lens lineup.

With P&S cameras, though, I think the reason that you can "switch" the camera into macro mode (and this is just a wild guess, mind you--I can't find any technical proof of it) is simply because the lenses are so damn tiny. I have an 8mm fisheye. I can maintain focus with the lens when it's touching something. And P&S cameras typically have 5mm-ish focal lengths on the wide end.

Also, many people will tell you airily that their macro is the equal of an L. Take that with a grain of salt. It's certainly true (or even an understatement) if all you care about is sharpness. But for contrast and CA control, the macro will not be the same. But it'll be damn good.

I also have to say that I personally disagree with the macro->everything idea. I bought my EF-S 60mm f/2.8 USM Macro in the hopes that I could also use it as a portrait lens. And I ended up getting a 50mm f/1.8 II anyway. The 60 was too slow and too sharp for my tastes. I really didn't like seeing every pore and nostril hair with alarming clarity when I took a portrait. YMMV.
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[addendum]

Yes, you can also use a macro like a regular prime, no restrictions. I've used mine to take landscapes; but I'm a panostitching fool.



full size

[vandergus]

I've also wondered what the macro mode in digicams actually does. My guess is that it's just a way to limit the focusing so when the camera is in non-macro mode, it doesn't have to hunt over such a long range to find focus. Long telephoto lenses sometimes have a focus limiting switch as well, to speed up auto-focusing. Same idea, i guess.

Or it could just be a marketing move to point out a particular feature.

[inkista]

Yeah, I've always wondered if there was some physical shifting going on--either the sensor shifted back or the rear elements of the lens shifting forward or something. But my head says that's too expensive, and focus limits make a lot more sense. I think you cracked it!

[Galiven]

Awesome. Thanks for info. Definitely clearer on the topic now. By the way, that panorama is pretty cool.