I am 100% new to shutterbug but I have been doing digital photography for a few years.
I recently got my 1st dslr, a canon rebel xt. I bought a separate lens for it (Canon EF-S 18-55mm f/3.5-5.6 IS). I love macro shooting I just wish it got a little closer. So trying not to resorting to a new lens I heard about extender tubes.
Has anyone used them on their cannon dslr? Are there good and bad points?
I am 100% new to shutterbug but I have been doing digital photography for a few years.
I'm not familiar with the Canon system, but besides using a dedicated macro lens, you have two options for getting closer. Extension tubes, which are empty tubes that put more space between the lens and the camera body allowing close (but not distance) focusing. The other option is close up filters that screw into the front of the lens.
Yes, I've been carrying extension tubes in my camera bags and using them extensively for 25 years or so, with various camera systems. Currently I shoot mostly with Canon. In my opinion, extension tubes are very useful, although perhaps not quite as convenient as a true, dedicated macro lens (like Canon's EF 100/2.8 USM and EF 180/3.5, both of which I use, or their EF-S 60/2.8 & EF 50/2.5, which I don't have).
First of all, please be aware that Canon offers "Extenders" as well as "Macro Extension Tubes".
Just to clarify, what Canon calls "Extenders" are teleconverters in common photography terminology. These are used to increase the effective focal length of lenses they are fitted to and come with some limitations. In Canon's system, these are really only usable on the telephoto primes longer than 135mm and certain of the zoom lenses, particular those in the tele range with apertures larger than f4 (in the case of the 1.4X) or f2.8 (in the case of the 2X).
Teleconverters (or "Extenders") do have some macro uses, but are generally more for really long lens work such as taking a photo of a distant bird, etc.
Canon's "Extenders" come in two magnifications - 1.4X and 2X and have high quality optical elements in them. These are not what you want to experiment with macro shooting.
Now, Canon's macro "Extension" tubes are just what Larry described, a simple means of moving the lens further away from the camera body so that it will focus much closer, which in turn gives higher magnification of small objects.
There are no optical elements in extension tubes. This is important because they don't change the optical formula of the lens, so can be expected to have minimal effect on image quality.
Canon offers two sizes of extension tubes, sold individually: 12mm and 25mm.
There are also third party macro extension tubes offered. Kenko is one common brand, and Adorama's ProOptic are another. Kenko offers 12mm and 25mm like Canon does, and both of these brands also offer sets of three tubes in differing lengths, which can be used singly or in combination with each other for a number of different ways to adjust macro magnification with many different lenses.
These sets are a pretty good deal, compared to individual tubes. A set typically costs around $90 to $160. Individual tubes seem to sell for around $l75 to $150.
I have and use both Canon's and the Kenko tubes myself. I don't see much practical difference between them. Some say the Kenko are plastic, while the Canon are metal and less prone to flex with heavy lenses and cameras. Also, some say the Kenko lens latch is not as strong as the Canon, and might allow heavy lenses to unlatch accidentally. I've used various extensions on lenses as large as 500mm and cameras like EOS3 with the power booster grip and 30D with vertical/battery grip, which are not lightweights by any means. I've had no such problems with any of my extension tubes, knock on wood.
Something very important, you might see on certain online auction sites and elsewhere that there are even cheaper sets of tubes available. Some as low as $25 or $50. However, these are "dumb" tubes. Just spacers. They don't have the electronic contacts that allow your camera to communicate with your lens. This means the lens can no longer auto focus, but more importantly also that the camera cannot stop down the lens' aperture (there's a work around, but it's cumbersome and slow to work with). So, I'd generally not recommend these, despite their low price.
Another very important thing, if you go with extension tube and want to use them with the EF-S lens you have (Canon's special designation for their "digital only" lenses, which have a slightly modified mount to prevent them being fitted to full frame cameras like the 5D), you have to be sure to buy EF-S compatible versions of any extension tubes. Older Canon, Kenko and ProOptic simply won't allow your zoom lens to fit.
Now, frankly, an 18-55mm zoom lens would not be my personal choice to use with extension tubes. A prime lens (non-zoom, single focal length) is what I'd generally use. I have used extensions with my Canon 70-200/2.8 with good success, though. It's one of those things you just have to try.
If you decide you want a fixed focal length lens, there's an inexpensive possibility. The Canon EF 50mm f1.8 sells for $100 or less and many consider it quite a bargain. It also doubles nicely for portraiture with nice background blur and low light photography, areas where your zoom would struggle. With extensions, it can also be used for macro or near-macro shooting.
The Canon EF 50/2.5 Macro lens also could be used and might be a bit sharper in some respect, but may be a little less versatile for non-macro shooting. It's also more expensive.
So, you might wonder how long an extension tube you need to achieve a certain level of macro magnification. Well, in theory you need to space the lens the same as it's focal length to get to 1:1 (life size, or a subject about 23mm wide on your camera's 23mm wide sensor). So, a 50mm lens would need 50mm of extension, at least in theory.
However, this doesn't take into account the lens' inherent close focusing abilities, and it has little relevance unless you are doing scientific photography or something else where very precise magnifications are important.
I've used a 12mm extension on a 20mm lens and had the flower petal actually touching the front of the lens in focus. Can't get much closer than that!
Conversely, I recently used a 36mm extension behind a 500mm lens to allow just slightly closer focusing on a hummingbird sitting on her nest, just the little extra needed to get the shot.
I think most people overestimate the magnification they really need, anyway. Visually, we mostly notice subjects 1:1 or 2:1 (twice life size) and larger with our bare eyes. Much smaller and you are using a magnifying glass or microscope to explore.
Larry is right, you have an alternative to attach a magnifier optic on the front of a lens, too. These attach just like filters do, but are clear of course.
The downside is that good ones like Canon's 250D and 500D aren't cheap. And, you need to buy one in the specific filter thread size of your lens, so it may not fit other lenses you eventually own. And, it gives one magnification (although the zoom and focus of your lens allow for changes in magnification).
And, cheap close-up lenses or "diopters", as they are more properly called, that you might find will usually seriously degrade image quality. Even the top quality ones might do so to some degree, too, sort of depending upon the lens you use them with. For example, using one with the much more complex optics of a zoom, the diopter's optics added in front of the lens are more likely to have some effect on image quality. Also, most diopters are not multi-coated, the way filters are, so there can be flare and loss of contrast in certain lighting conditions, if you aren't very careful when using them.
Personally, I just find extension tubes more widely usable and have made a point of keeping a set handy with each of my camera systems for many, many years now. And, I don't worry too much about magnification ratios. I just fit one and give it a try. If I want more magnification, I'll fit a longer one. With some experience, you can get pretty fast at doing this and more sure with your selections for particular lenses.
I would also highly recommend some reading about macro photography. There's a lot to learn, many ways to do things and it's great fun. There are special focusing techniques, flash is very useful and there are other helpful accessories you'll probably eventually want to experiment with. You might start by checking Amazon.com for books about shooting close-ups written by John Shaw and Tim Fitzharris, among others.
I use the Kenko three extension tube set. I ordered this kit for around 100 bucks from eBay from a respected seller in Hong Kong. There is no glass in extension tubes so optics are not affected. These work as they are supposed to for macro work. Recommended.