A tube set usually ships with two or three pieces that can be combined in any order, and stacking all of them at once feels like the obvious way to get the most magnification. There is a practical ceiling, though, where added length stops paying off and starts costing you light, working distance, and sharpness. This article works through where that ceiling tends to sit and how to recognize it with your own gear.
Why the Gains Shrink With Every Added Tube
Magnification from a tube set adds roughly in proportion to total tube length, so stacking three tubes instead of one does increase magnification by a meaningful amount. What changes is how useful that extra magnification actually is once depth of field has already shrunk to a sliver with the first two tubes. Adding a third tube pushes magnification higher but often leaves so little in focus that the gain is not usable without stacking several frames to compensate.
There is also a point where the lens is simply being pushed well past the distances it was designed to resolve sharply. Corner softness and reduced contrast become more noticeable with each added tube, particularly on lenses that were not built with close focusing in mind to begin with.
Light Loss and Working Distance Both Compound
Each tube added to the stack reduces the light reaching the sensor a little further, since the lens is effectively working at a smaller aperture the further it sits from the sensor. By the time a full three-tube stack is attached, shutter speeds often need to drop or ISO needs to rise compared with a single tube, which matters for handheld work in particular.
Working distance shrinks at the same time, and for some subjects this removes any benefit the extra magnification would have offered. An insect that tolerates a lens eight centimeters away may fly off the moment that distance drops to three centimeters with a full tube stack, which defeats the purpose of reaching for more magnification in the first place.
Finding the Practical Limit for Your Own Lens
- Test one tube alone and check sharpness at full zoom on screen
- Add the second tube and compare the same test shot
- Add the third and note where focus becomes too thin to use handheld
- Settle on the combination that still lets you compose comfortably
Alternatives to Stacking Every Tube You Own
If the full stack pushes magnification further than a single subject needs, using only two of the three tubes often keeps more usable depth of field while still reaching a meaningful close focus distance. Save the full stack for subjects that genuinely need the extra reach, such as very small insects or fine texture work, rather than using it as the default setup.
Pairing a shorter tube stack with focus stacking across several frames is often a better route to extreme detail than relying on the longest possible tube stack in a single frame, since stacking recovers depth of field that a longer tube stack would otherwise sacrifice.
Mechanical Stress Increases With Every Tube
A full stack of tubes adds real length between the lens and the camera body, and that length becomes a lever every time the setup is picked up or set down. Supporting the lens barrel with a free hand rather than letting the mount carry all the weight matters more with a three-tube stack than with a single short tube.
On a tripod, using an arm or a focus rail to support the lens itself, rather than relying on the camera’s tripod socket alone, reduces strain on the mount during long stacking sessions where the rig sits assembled for extended periods.
A Worked Example With a 100mm Macro-Friendly Lens
Starting from a 100mm prime with a decent close focus distance on its own, adding a single 20mm tube nudges magnification up by a fifth, a change most viewers would barely notice in a side by side comparison. Adding all three tubes from a typical set, roughly 68mm combined, adds closer to two thirds of a unit, a far more obvious jump that moves a shot from a cropped-in flower to genuine insect-leg detail.
The catch shows up in the same test: shot at the same aperture, the three-tube version needs almost a full stop more exposure and shows visibly softer corners next to the single-tube version. For a photographer who mainly wants a closer flower shot, one tube does the job with far fewer compromises than reaching straight for the full stack.
Frequently Asked Questions
Most tube sets allow stacking all pieces together, so there is no hard mechanical limit, but image quality and usable depth of field usually set the practical limit well before that.
Yes. Each added tube reduces light further and narrows depth of field, both of which make autofocus hunting more likely, so manual focus becomes more useful with a full stack.
A set of shorter tubes gives more flexibility, since you can combine them to hit several different magnifications rather than being stuck with one fixed length.
No. Shorter focal length lenses gain more magnification per tube than longer ones, so the point where returns diminish comes sooner on a wide lens than on a telephoto.
Only if you regularly shoot macro on two lenses with very different focal lengths. Otherwise the same set, used in different combinations, usually covers both occasional and dedicated macro needs.
The Short Version
Stacking every tube in a set does increase magnification, but light loss, shrinking working distance, and thinning depth of field all compound with each added piece. Test your own lens at one, two, and three tubes to find where the combination stops being practical for the subjects you actually shoot, rather than assuming more tubes is always better.