Stopping down a Canon EF lens

If you’re used to manual lenses, you know how easy it is to stop them down. If you are a little bit more advanced than that, and have ‘graduated’ to more advanced lenses, stopping down a lens (i.e making the aperture smaller) while it is not attached to a camera body can get a little problematic. There is a way to do it, however…

All of Canon’s newer lenses (the whole EF and EF-S series) have electronically controlled aperture. Normally, that’s great, because you can select what aperture you want with the thumb wheel or via the camera’s menu system, instead of having to do it with a wheel on the lens itself.

There is a trick you can use to stop down lenses, however. Mind you, this is probably a bad, bad thing to do, and it may break stuff. Having said that, I have been doing this for years, and it seems to work fine, without any adverse effect.

A stopped down lens should look a little bit like this. Or a lot like this, in fact. The size of the hole depends on how far you've stopped down your lens.

Stopping down a lens is done by putting the lens on the camera, and setting the camera to either manual aperture (A or Av) or fully manual (M). Select the aperture you want. Then, press and hold the aperture preview button. If you don’t know where that button is, it is probably the one near the bottom of your lens, on the side. The one that you never use. Yes, that one. Press it, hold it, and then take the lens off the camera exactly like you would do normally.

If you have done it right, you are now holding the lens, which should still be stopped down. It should look approximately like in the picture with the red circle.

Finally, this trick for setting the aperture is not a “recommended” method (not that there really is one), but at worst the “ERR 99? or “ERR 01? it may produce on the camera can be cleared up by turning the camera off and back on.

Well, this trick will come in most useful when you’re using your lens detached from the camera, obviously. This would come in particularly useful in macro photography, such as if you are using non-electronically connected spacers between your lens, so your camera can’t send the right signals to the lens to make the aperture change.

If you are reversing your lens with a set of reversing rings (or using my nifty homemade lens extender), it would also be useful, if you want to use the lens at anything other than fully open.

And hey, it’s a nifty trick. Sometimes, that ‘s all you need, right?

Finally, if you like this post and want to learn more about macro photography, check out my book on macro photography (in the sidebar over there ?).

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