Extension Tubes and Ring Flash?

A reader asks on my Comparing macro lenses to extension tubes page whether or not hot-shoe or ring flash will work with extension tubes, or whether the working distance is too close.

Answer #1: I don’t know. Answer #2: Let’s find out.

I set up a tripod, put a 6 mm extension tube on a 16 mm lens, and asked Uiharu to model for me. The crinkled paper was intended to give a bit of light bounce from the room lights, but I ended up shining a flashlight into the paper to push up the brightness.

Extension Tube Test Setup.

Setup for the extension tube test.

As you can see, she’s pretty close to the lens; about five centimetres away, or two inches for the metric impaired.

Top view, test of extension tubes

Even being so close to the lens, Uiharu is still brave.

Here’s a test photo with the room lights on, and me shining a flashlight into the crinkled paper to get some fill on the face.

Extension Tube Test

Photo with extension tube, 5 cm from the lens. Room light, with flashlight bounce from below.

Next, we try adding a ring flash. Given the flash is a little more than a centimetre, Uiharu is now about four centimetres from the front of the flash.

Extension Tube Test

How close must I loom to frighten you, Miss Kazari?

The photo turns out well; nice definition and modelling in the shadow areas. I’d say ring flash works just fine.

Extension tube test with ring flash

However, a flash on the hotshoe of the camera doesn’t work very well, as Uiharu is hidden by the lens itself. The camera exposes for the wall, and all you get is either a silhouette, or a blown out photo.

flash test seup

A hot-shoe flash can provide a glancing edge light, but not enough light to take a good photo.

So, in summary, ring flash does work well with extension tubes, just as it does with macro lenses. Of course, this assumes your subject is at least one or two inches away. If your subject is touching the lens itself, then all bets are off. A flash on the hot shoe just doesn’t work well at all, unless your subject is about 20cm or further away, at which point you can’t focus with an extension tube anyways.

Comparison of room light and ring flash in macro photo

Macro photo with 16mm lens and 6mm extension tube. On the left, room light. On the right, ring flash. Working distance of about 5 cm. Histograms shown.

3 Responses to “Extension Tubes and Ring Flash?”

  1. Laurie Says:

    THANKS!!! that is very helpful — will go with the ring flash / ring light! I know at some point I need to get a hot shoe flash for non-macro stuff and stop relying on the built in flash for my digital Canon EOS XSi – but this info helps me prioritize for sure!

  2. Jason Steel Says:

    Thanks for posting these results. Very interesting. I’m very keen to take some wide angle macro shots of wildlife using a Canon 40D camera and the Canon 10-22mm lens at about 14-15mm.
    I can’t find a 6mm extension tube though to fit this camera and lens combination and wondered if you know of anywhere that sells one as you’re using a 6mm tube in your tests?



  3. darren Says:

    Extension tubes should more or less be compatible across the entire Canon EOS line. I picked mine up at BIC camera in Tokyo (probably doesn’t help you) but any camera store should sell them.

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