macro lens vs regular lens - DPChallenge Forums

Canon EF 70-200mm f/2.8L IS USM

05/03/2004 03:43:42 AM · #1

i am a little confused about macro lenses and regular lenses.
i have a 28-135 IS USM lens ..
compared to the canon 100 macro lens... what is the difference, or i mean, my lens can shoot at 100 mm.. so why does the 100mm lens magnify more. i thought if i wanted more magnification i would need a 400mm lens or something..??? .. can you change the magnification with a macro lens? if so doesn't that change the focal length then?.. or no?... does the focal length mostly have to do with distortion and not so much with magnification...
signed confused.

gajmaj

Canon EOS-20D

05/03/2004 05:14:03 AM · #2

Hi Leaf,

I'm definately no expert and I had the same question. It's all about ratio to lifesize. These two URLs should answer a lot of your questions in this realm:-
//www.marietta.edu/~mcshaffd/macro/macro.html
//www.marietta.edu/~mcshaffd/macro/lenses.html
There's a heap more info on this site too about macro photography.

Cheers

EddyG

Canon EOS-1D Mark II

05/03/2004 09:19:55 AM · #3

Originally posted by leaf:

so why does the 100mm lens magnify more

It is all about "closest focusing distance". Macro lenses can achieve focus much more closely to the subject than a non-macro lens.

For example, the 70-200/2.8L IS zoom lens has a "closest focusing distance" of 4.6 ft. Sure, it is a 200mm lens and magnifies things, but it can't focus up close. One solution to that problem are close-up lenses, commonly referred to as 250D and 500D. Screwing the 500D close-up "filter" on to the 70-200 will allow it to focus up close and work as a nice close up lens. (Although the results are not as good as you get from using a true macro lens.) For the 28-135, you would use the 250D. Another solution is to use extension tubes, which physically move the lens further away from the camera body. This allows closer focusing, but like the close-up attachment, you lose the ability to focus at long distances (i.e. infinity).

The other thing about "true" macro lenses are their fine focusing adjustments. Because of the extremely shallow DOF when shooting up close, you need very fine control of the focusing mechanism. So a macro lens will typically have a very fine focusing adjustment mechanism. It would be cumbersome to have this fine control in normal manual-focus situations because you'd have to twist-twist-twist to adjust the focus, and in auto-focus applications, the AF motor has to actuate that much longer (which takes more time). But when shooting macros, you need that type of control in order achieve exact focus.

So there is a difference optically and mechanically between a "normal" lens and a "macro" lens, even if they have the same focal length.

Count

Canon EOS-30D

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

05/03/2004 09:42:00 AM · #4

Thanks Eddy

Well put.

05/03/2004 01:02:27 PM · #5

thanks yeah.. that puts it straight.

Canon EF 28-135mm f/3.5-5.6 IS USM

05/03/2004 03:55:39 PM · #6

ok here is another question along the same lines.

say a 300mm lens, that is a telephoto macro lens.
does that mean it has a focus distance like a regular lens, in addition to being able to focus very close?

like this one
can all macro lenses also focus at a larger distace ...
i have heard a fair bit of talk about this canon 100 mm one

GoodEnd

Canon EOS-350D Rebel XT

05/03/2004 04:25:58 PM · #7

Originally posted by leaf:

This is a telephoto with macro capabilities. It means that you can focus at small range (for the lens focal length). In this case 47" is a smal distance. But itÂ´s a huge distance compared with classical macro lens that can focus at 1.5" or 2". Macro lens gives you the ability to get very close to the subject. But there is an optical limit to this and this limit is largest as the focal length increases. This is why the 100 mm are so desired. In pratical terms your application defines your needs and you must decide based on it. Read carefully the lens tech specs to achieve the most useful focus range. All lens have infinity focus but not all has the ability to focus at 2".

Message edited by author 2004-05-03 16:28:04.

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

05/03/2004 04:26:29 PM · #8

Originally posted by leaf:

Yes, but be careful of lenses that just use "macro" as part of their description, vs. true macro lenses. True macro lenses usually are capable of 1x magnification (or at least 0.5x); many normal lenses that have "close-up" capability use the term "macro" to describe what may be only 0.33x or 0.25x magnification.

Originally posted by leaf:

like this one
can all macro lenses also focus at a larger distace ...

Most macro lenses can focus to infinity (except the special purpose Canon MP-E65). The lens referneced above is not a true macro lens. It just has close-up capability (max. magnification is 0.33x)

Originally posted by leaf:

i have heard a fair bit of talk about this canon 100 mm one

The Canon 100/2.8 Macro is about the most versatile macro lens out there. In addition to being a superb macro lens, it is also a wonderful portrait/short telephoto lens. It is one of the sharpest lenses Canon makes (L or otherwise) and has quick, precise USM focusing, with full-time manual override. What's not to like?
Alternatives to the Canon 100/2.8 are:

- Sigma 105mm macro (nice lens optically, slow focus, quirky AF/manual switching)
- Tamron 90mm macro (another nice lens optically, slow AF)
- Canon 50mm macro (only 0.5x magnification, 1.0x requires additional accessory)
- Canon 180mm macro (fantastic lens, very expensive ($1100 US)

Canon RF 24-70mm f/2.8 L IS

05/03/2004 10:54:47 PM · #9

allright, another question...
(i will know it all soon)

what does 1:1 magnification mean?.. i know it means that it will take the picture 'life size', but if i am taking a macro of a ladybug.. life size.. well.. a lady bug is pretty small in life size.. i can't see much detail.. so 'life size' doesn't sound that impressive, but i know that 1:1 is quite large (right) ... how is it measured.. what is life size?

kirbic

Canon EOS R5

05/03/2004 11:01:38 PM · #10

Originally posted by leaf:

If the bug is, say, 5mm long then it's image on the sensor will be 5mm long, that is 5mm:5mm or 1:1. When you print the image from the 15.1mmx22.7mm sensor at 4x6 inches (100x150mm) the bug will be 33.6mm long.

Make sense?