>>3599070>Would something like Sony's 23mm still be usable with extension tubes?
For such a short focal length, it would be better to use a reverse ring. The working distance is going to be terribly short regardless. Longer extension will mean shorter working distance. Yes, you can use a 23mm lens for this, but not with much extension. You can test it out in reverse by holding the aperture lever wide open while holding the lens up to the camera body and taking a pic. The working distance will be about 1-2 inches (2-5cm) from the camera lens I think. If it works for you then consider getting a reverse ring with aperture adapter so you can manually adjust the aperture opening if your lens is electronically controlled without aperture ring. You can even reverse it then stack some extension on. Some lenses just don't work out well with that though, so give it a test.
This image was with a reversed 38mm lens and 171mm extension tube.