A bit unclear about extension tubes...

I mean I'm currently thinking about getting a macro lens, but then I did some research and found out that with about 48mm of extension tubes on my 50mm F1.8 II I can get to the 1:1 macro range for alot smaller cost than buying a dedicated macro lens. What are the cons of extension tubes, there has to be a "catch"?

I know that extension tubes disable the ability to focus to infinity but that doesn't really matter since I can remove the tubes if I want to shoot normal distances. I also know that extension tubes limit the max aperture (with 48mm of extension tubes the max aperture with the 50mm is 3.1 and with 68mm it 3.5) but that doesn't really matter either since you usally shoot macro at small apertures like F11. So is there something I dont know? Is the DOF smaller than with a real macro objective? What about the area where I can focus, is it really shallow or can I still focus to like a meter away?

Extension tubes will reduce the maximum aperture, and there is light loss so the image in the view finder is darker. so long as you have a set with electrical contacts for EOS, you will retain aperture control which is very important, and AF, which is considerably less important.

tubes are a good cheap way to get into macro, but they are not particularly easy to use - it takes practice and a tripod is essential for high magnification and small apertures, because shutter speeds will be very low. the same applies to dedicated macro lenses BTW - tho they are easier to use.

You can also use extension tubes on macro lenses to increase magnification further. And on the Canon 180 L macro lens, you can even use teleconverters to increase the working distance ( and lose 1-2 stops of light)

The Canon Life-Size converter designed for the Canon 50mm f/2.5 macro works like a combination teleconverter and extension tube, and can, contrary to Canon's advice, be used on any EF lens - there is a thread about it elsewhere, comments by CDS, if you do a search it will come up.

Alrighty...

Tubes can be a really good way to get decent macro and close-up shots. They are definately a lot cheaper than getting a macro lens, and I think most people in here would recommend giving them a try. Your DOF is going to be extremely shallow, whether you use a real macro lens or tubes. It's just a matter of aperture to distance from subject. You can't get around it.

Using your 50mm and a full stack of tubes, you probably wont' be able to focus even a foot away, but you will end up with about 1.3:1 magnification. Even with just a 12mm tube, you won't get much working distance at all. The longer the focal length of the lens you use, the more working distance you will get. I like to use my 70-200mm f4 L with the tubes for butterflies and such.

The main 'con' of tubes is the magnification and working distance. At 70mm, you will get about 1:1 magnification, but you won't have much working distance. If you have a 100mm macro, you will get more working distance with your 1:1 magnification, and the ability to use tubes to give you even more magnification. I think that is what most people use when you see a super-close-up shot of a bug.

Hope this helps. I would say to get some, any brand is fine as long as it has contacts to communicate between the lens and body. Play with them for a while, and if they don't do all you hoped for, get the macro lens. Then you will have the tubes still to use with your macro lens.

In Macro you have to acount for `Bellows Factor' with ANY lens. TTL metering handwaves most of the mess for you. The only downsides are less convinient to use as you swap them in and out, and using a lens away from its designed range. A bellows is less hassle if you are using long extentions, but not if you only need a little extra draw.

An excelent starting set for almost no money is a bellows and a good enlarging lens. El-Nikors are almost a give away at the moment.

The tubes will give you about the same working distance, and the same light loss, as a macro focussed to the same magnification. Where macro lenses shine is that they're corrected to work all the way down to that magnification; your 50 f/1.8 isn't. It won't be bad at 1:1, just a little less crisp and with slightly more aberrations than a macro will produce. OTOH, that's well within what most people can live with. You will also lose "instant" transition between close-up and infinity focus. You'll have to get rid of the tubes during the transition. Still, it's a bunch cheaper than a macro lens, and more flexible since the tubes will work on any of your lenses (but don't try it on a real short lens, and not all tubes will work with EF-S lenses).

There's a thing called A reverseing ring which enables you to use your 50mm the other way round there about £15 of ebay but you have to focus by moving the lens and camera but people get good results with them