Macro capable... what does it mean?

PilotBrad

I was perusing the interwebs today and came across something where it said my current 17-55 f2.8 lens is not "macro capable", however I was surprised to see that my old 18-55 f3.5-5.6 kit lens was stated to be "capable".

I'm learning, and while I vaguely understand the concepts of magnification and close focusing distance, what would make one lens macro capable and another somewhat similar lens not?

GOLDENORFE

hard one to answer, but the deffinition of macro means producing an image of life size on the sensor. so neither lens would be capable of doing that.
probably just a marketing / selling point.
on crop sensor canon body x1 life size 22mm fills the width of the frame, this is true macro.
a set of kenko extension tubes to increase magnification would work on any lens, but focus distance would be quite short.

for this shot i used 18-55 standard zoom at its 50mm position with a 12mm extension tube added, focus distance about 4 inch

phil

PilotBrad

Thanks Phil... nice shot!

I read it on wikipedia (here and here), which doesn't necessarily mean it is accurate, but I did find it interesting.

I know it's not a macro lense, but I've been trying some close-up flower shots with the 17-55. I'm just not having much luck. I can't get close enough and the images are really lousy even though I've tried in both AF and MF modes. I got good results with the 18-55 on my Rebel, but I suspect it is because the close focus distance was shorter and the magnification greater on that lens (compared to the 17-55).

At first I thought I was having a problem with the 17-55 lens, but as I experiment and learn I think I was just asking it to do things it's not intended for or capable or of doing.

I'll give the extension tube thingy a shot.

Qarik

I assume it just means the min focusing distance is much shorter on your older lens is all.

Lord Vetinari

Quite a few zoom lenses have a "macro" focus position but in general as already commented they will focus just slightly closer than perhaps normal giving around 0.2:1 to 0.3:1 magnification compared to macro primes giving 1:1.
Brian v.

PilotBrad

Thanks guys! With your help, I think I am putting this all together.

The 17-55 has a max magnification of .17 @ 55mm. Because of the relatively low magnification, I was pushing in right up to the close focusing distance of ~14 in, which I think then led me to run into DoF limitations.

Ironically, the 18-55 has a max mag of .34 @ 55mm and a close focus of ~10in, which gave me me double the magnification AND allowed me to get in closer, thereby increasing the magnification effect even more. This explains, at least partly, why I had been getting better results with this lens.

The moral of the story for me is that I really do need to understand the capabilities of my equipment.

So with the 17-55 maybe I'll just have to stick to big sunflowers.

mehampson

It's really the marketing team that determines whether a lens is 'macro capable' or not, unfortunately. I have a 28-105mm zoom with a 'macro' label on it that provides 1:5 magnification.

tomhooper

Might I suggest you get some extension tubes. You can use them on that lens I think. It will allow you to get a much closer focus. If you use the extension tubes you will lose infinity focus, but if you are trying for a macro shot you don't need it anyway. You can get an inexpensive set of Pro-Optic extension tubes from B&H or Adorama, I'm not sure which for about $90.00. Set of three in different focal lengths. I have a set and they work just as well as my Kenko not to mention my expensive Canon's. Give it a shot.

IPClark

I agree with the Ext. tube advice.

I have Kenkos which allow AF if required however if you're really wanting to try them out and minimise outlay, you can pick 'em up on the likes of Ebay for under $20 but would not have AF ability.

mehampson

Adorama sells the Pro-Optics. There's a Budget line that's AF capable for $50 -- I have a set, they're cheaply made, and the contacts are solid metal rods so I worry a bit about wearing on the lens/body contacts, but they do work.

ole doc

I've never found I could reliably use AF close up, or maybe I'm just old fashioned.
Nick

Qarik

ole doc wrote:

I've never found I could reliably use AF close up, or maybe I'm just old fashioned.
Nick

not just you. best results will be manual focus. I think most macro shooters do this anyway. They set the focus where it is needed then slowly rock back and forth or try to stay steady and tweak the focus ring manually.

Lord Vetinari

With extension tubes - the importance of having electronic contact ones is not normally AF, it's so you have aperture control.
Brian v.

mehampson

Yeah, definitely AF is not the way to go -- I should have been more precise about that in my earlier post -- but the contacts allow the camera to stop the lens down, which is invaluable.

You can get around it with tubes that don't have that, on Canon lenses anyway, by holding the DoF preview button down while you take the lens off, and it'll keep the aperture closed down to whatever you've got it set to. You'll lose brightness in the viewfinder this way, but probably better than trying to shoot wide-open all the time.

tomhooper

I have no problems with aperture control on any of the extension tubes I use including the Pro-optics. As far as AF is concerned I only use it when I'm shooting what I call long lens macro. I use a tube behind my 300mm and can get some pretty fair shots. You lose a little detail and the shots appear a little flat (at least to me) but they are better than none at all. I have to use the AF on these shots because unfortunately my eyesight is not what it used to be.