Fundamentally, extension tubes and macro bellows do the same thing. They move a lens further away from the camera focal plane, which increases the magnification.
Differences in size, weight, cost, and fine adjustments means that neither is outright better than the other. The best option between the two is going to come down to use case.
If you are interested in using either a bellows or extension tubes, take a look at the Beginner's Guide to Macro Photography.
- Fine adjustment of extension.
- Easy to balance weight on a tripod.
- Do not need to worry about stress on the camera mount.
- The heavy weight absorbs and reduces vibrations.
- More expensive than extension tubes.
- Big and heavy, which is bad for transportation and field use.
I prefer bellows, specifically the Nikon PB-4 bellows, instead of extension tubes. A big part of this is because for outdoor macro, I will stick to a macro lens capable of 1:1 magnification.
If you don't need a solution that is lightweight or small for travel, quality macro bellows are a great choice.
Extend a lens far enough, and the image quality is going to be poor. How far a lens can be extended is different with every lens. With a bellows you are able to have fine control over that adjustment.
Stability is also better if you have a heavy bellows with a built-in focus rail. The focus rail can be used for fine focus, but more importantly, it can help to evenly balance the weight of your setup on a tripod.
If you don't have a camera with an electronic shutter, or you can't use that feature, the weight is good to have. A heavier setup will help to reduce vibrations from the camera shutter.
- Less expensive than a bellows.
- Lightweight and easy to transport.
- It can have electric contacts for lenses.
- A long extension can put stress on a camera mount.
- Without support, vibration can be a problem.
- Limited to extension distance based on tube lengths.
If you're just looking to give macro photography a try, a quality bellows might be more than you're willing to spend. Or, if you want to do your macro photography outside.
New or vintage used extension tubes are widely available and inexpensive compared to macro bellows. Plus, depending on the camera system you use, it may be important to have electrical contacts to control the aperture diaphragms of your lenses.
Beyond the price, extension tubes add less size and weight than a bellows. This makes them far easier to carry around outside and use without the need for a tripod.
Combining extensions tubes to get a specific length can be difficult. However, it will not be a problem for 50mm or 55mm lenses.
50mm and 55mm are the most common focal lengths for vintage macro lenses. Many of these lenses required an extension tube to be used to achieve 1:1 magnification.