Our readers frequently ask us about extension tubes for macro photography. Since I am not much into macro myself, I have not explored this area of photography enough to qualify to write about it. While I have done some macro photography for product shots and ring shots in weddings with my Nikon 105mm f/2.8G VR lens (a very sharp lens that I absolutely love), I have not explored its full capabilities and I have not tried to use extension tubes and bellows to do crazy things that you can achieve with a true macro setup. Meanwhile, our readers have been gracious enough to fill in, and I have recently received the below post from one of our readers, Usama Nasir, who talks about what extension tubes are and how they are used in macro photography.
If you find yourself frustrated by the minimum focusing distance of your lens, if you constantly find that you’re unable to frame the shot you want, because you can’t get close enough to focus, then you may want to consider using extension tubes.
How Extension Tubes Work
An extension tube is an attachment that goes between your camera body and your lens. It’s not an optical element, so there is no glass involved. All it does, is get the lens further away from the focal plane. Now, the practical upshot of this, is that your minimum focusing distance gets smaller. So, with an extension tube, you can get closer to your subject and thus fill the frame with more of it.
For example, I have the Canon 24-105mm lens, which has a minimum focus distance of 1.48 feet (0.45 meters). The above shot is as close as I can get to this flower. Nice enough, but I like to get in closer, so I’m going to add one of the extension tubes (I have three of them and we’re going talk about their differences shortly). Extension tubes simply go on your camera body like a lens. So, I’m going to take my lens off, attach the shortest extension tube on the camera body, then attach my lens to the other end of the extension tube.
The reason I’m choosing the shortest one, is I don’t want to go in real far – I just want to get a little bit of boost in magnification. With this setup, I am now able to physically get closer to my subject and photograph at a greater magnification. Now, there is a trade-off to using extension tubes – they can eat up some of the light. I may have to increase my ISO or potentially decrease my f-stop (aperture) to get a little more light. And if I use a wider aperture, then I’m going to have less depth of field to work with. So, there is this trade-off of magnification versus depth of field. But what’s nice, is that I got in closer – something that I was not able to do before with the bare lens.
The nice thing is that I don’t have to worry about cropping my image in post-production just to try to get closer to my subject – I get to use more of the pixels in my camera. You can use extension tubes with any type of lenses: primes or zooms, portraits, or even macro! Extension tubes are an inexpensive way to get the kind of short focusing distances that you get from a dedicated and much more expensive macro lens.
Extension Tube Sizes
Extension tubes come in different sizes. I have a set of three Kenko Extension Tubes (here is the Nikon version). I have one that is 12mm; a longer 20mm one; and the longest one is 36mm. I can also stack these together. As I stack them, they obviously get longer. And, as they get longer, I get more extension, which means more magnification power. Once I attach this setup on my camera, I’m going to be able to get all the way into the full macro range, which is going to open up all of the macro concerns and practices that I’m going to have to think about as I’m shooting that close.
The effectiveness of extension tubes decreases as focal length increases. That’s because the additional magnification you get is the length of the extension tube over the focal length of the lens. Thus, while a 25mm extension tube will give you an additional 0.5x magnification on a 50mm lens, it will only give you 0.125x additional magnification on a 200mm lens. Thus, extension tubes are most useful on lenses less than 200mm. Here are the additional magnifications offered by three different sizes of extension tubes for 50mm and 100mm:
|Extension Tube Length||Focal Length||Additional Magnification|
One other very important thing to understand about extension tubes is that some of them have electrical contacts that allow your camera to communicate with your lens, and some don’t (the above linked versions do).
If you get tubes that don’t, then you won’t have autofocus capability or aperture control. Now, Canon and Nikon both make sets of active extension tubes with full electronic contacts. While they work great, they are obviously very expensive. Kenko extension tubes that I personally use are much cheaper than brand versions and you could even get cheaper ones from other third party brands like Vello. My extension tubes have the much-needed electronic contacts, giving me full autofocus capability, and yet they cost much less than the Canon tubes.
Extension tubes are a very affordable way to start getting into macro photography. What’s more is that they are small, lightweight, and easy to carry around. If you are worried about whether you should invest in extension tubes, or go ahead and invest in a true macro lens, bear in mind that sometimes you’ll need to get a macro lens closer to your subject, so you’ll continue to use extension tubes, even if you eventually buy a macro lens. In the meantime, they’re a great way to start experimenting with close magnifications using your regular lenses in your arsenal.
Disadvantages of Extension Tubes
Extension tubes have some disadvantages compared to true macro lenses. One small disadvantage is that lenses that are not made to be true macro lenses may not be well-corrected for close-up usage. For example, a lens may work pretty well on its own but have noticeable fringing and softness in the extreme corners when paired with extension tubes. That’s not a huge problem and you can still do plenty of nice macro shots as long as you keep this in mind.
But there is one other, much larger disadvantage of extension tubes. Not only do they decrease your minimum focusing distance allowing you to get macro shots, but as a side effect, they also decrease your maximum focus distance as well! In other words, you will not longer be able to focus at infinity. In fact, you will barely be able to focus at any normal distance at all, so that macro will be the only thing you can do. Even portraits of people will not work with most lenses and tubes.
Finally, you also need to be careful when working with extreme wide-angle lenses. If I put the 68mm stack of tubes on a 20mm lens, I won’t be able to focus at all, because my minimum focusing distance will be pulled back into the inside of the lens.
Other Means to Get Closer
Extension tubes are not the only way to get closer to your subject. You can also purchase close-up filters, dedicated macro bellows that have much more flexibility than extension tubes and can potentially be used to move your plane of focus like tilt/shift lenses do (can get quite expensive) and you can also utilize adapters to use normal lenses in reverse position (which basically converts normal lenses into macro lenses). There are also other types of cheap DYI solutions that can effectively achieve the same results as using extension tubes or bellows. I would encourage Photography Life readers to dig into this subject more, because there is so much to explore in the world of macro photography.
max magnification=(lens magnification)+(Extension Tube length)/(lens focal length)
do extension tubes work for an extension to a 300mm telephoto lens so that I am closer to a bird vs. buying a very expensive lens ? just curious. a novice at best
The maximum magnification increase will be very small with 300mm, so it’s not worth it.
There is a typo…”With this setup, I am not able to physically get closer to my subject and photograph at a greater magnification”
Should be “With this setup, I am NOW able to physically get closer to my subject and photograph at a greater magnification”
if i have a 55mm f1.8 prime, if i add a 20mm tube. does that just mean i will have a 75mm lens? i believe my prime has 0.4m minimum focus distance.
i still dont know how many tube i need to buy….
Your website have every answer for photographer very nice.
A fine explanation about extension tubes thank you….
Yes, macro bellows have an essential role in macro photography. Bellows are used from earlier cameras to modern cameras. It is becoming various dimensions depend on the technology.
Since i bought my DSLR i am very much fascinated to macro photography. But my budget doesn’t permit
me yet to buy a good macro lens. Can i use extension tube on my kit lens AF-S DX NIKKOR 18-105mm f/3.5-5.6G ED VR??
Great article. I have been using extension tubes since my father taught me photography as a boy. He gave me an Exacta vxiia slr from the early 1950s with three Zeiss lenses, a set of extension tubes including a set of close-up magnifying filters. I certainly learned a lot using these as the Exacta had no built in meter, so I had to learn to compensate for the falloff in available light. I used my old Weston meter with a light cell and then did the calculations for the correct exposure depending upon the length of the extension tubes, or combination of tubes. I only used the 50mm f/2 Zeiss lens with the tubes as that was my sharpest lens.
I suggest people who have an interest in macro photography experiment with these, if you have an inclination to go beyond the limits of your macro set up. I don’t use them that much anymore , but this article has inspired me to do so.
A rough guide to magnification ratio is that if the extension length = the focal length of the lens, you get 1 : 1. Genuine macro is seldom used, except for technical work, because of the very narrow depth of field.
Longer lenses allow a better working distance from the subject, but run a greater risk of camera shake and the extra extension costs more light. By the time the lens is stopped down to its sweet spot, (usually 3 stops) the EV is so low that the shutter speed is too short or the ISO is too high.
The ‘old school’ solution is flash. Which gives a sharp image and allows for a smaller aperture. I use 3. A main, a fill and a background light to avoid the ‘shot at night look’ of many close up shots.
Macro/CU, opens up many interesting worlds, wildlife, engineering, food, still life, etc. It is also one of the areas in which ingenuity can substitute for mountains of money.
Oops, I was thinking about a piece on reciprocity failure, I should have written that the shutter speed is too long. Sorry for any confusion.