Ever since I bought the 1.6x crop factor Canon EOS 10D I have been looking for a real wide angle lens (as you know 17 mm is not very wide on the 10D), this probably being a universal problem for users of 1.6 crop factor digital SLR. For a long time I was hoping that Canon would remedy this obvious lack in their lens chart, and they finaly did with the EF-S 10-22/3.5-4.5 super wide angle lens. Unfortunately for me it was made in the EF-S mount that was introduced with the Canon EOS 300D, making it impossible to mount on the 10D and older cameras. This also meant that Canon will not introduce a real super wide angle lens that can be fitted the 10D, although third party manufacturers recently have shown that such lenses is actually possible.
Since the introduction of the EF-S mount prosumer Canon EOS 20D I have therefore been tempted to replace my Canon EOS 10D, since it would solve my lack of a real wide angle lens. But I have always felt that I can not justify the upgrade for this reason alone.
Two things made the EF-S mount possible, the smaller mirror of the 1.6x crop sensor and the special retracting mirror mechanism. As other has showed, the smaller mirror in the 10D actually makes it possible to mount the Canon EF-S 18-55/3.5-5.6 kit lens after cutting of the protruding rear end of the lens body. What if it was possible to actually mount Canon EF-S 10-22/3.5-4.5 lens on a 10D?
This thought followed me for a long time, but the Canon EF-S 10-22/3.5-4.5 is a bit too expensive to cut apart not knowing if it will work in the end. But this article on the Internet, describing how to mount the EF-S 17-85/3.5-5.6 IS lens on the 10D, made me think it might be possible to do something similar to the Canon EF-S 10-22/3.5-4.5 lens. As it turned out it was possible, albeit with some restrictions.
Disclaimer: The author takes no responsibility for any damage caused by following the instructions outlined below.
First of all I want to make clear that the retracting mirror in the EF-S mount do make a difference, the rear lens of the Canon EF-S 10-22/3.5-4.5 lens will hit the mirror with the lens set to maximum wide angle. So we can not use the lens at full wide angle while mounted on the 10D. Luckily the margin is very slim, so the practical differences is negligible (point at the picture below to see the difference).
It turned out to be a very simple modification, was far easier than I had expected. Begin with removing the protruding plastic ring that is stopping us from mounting the lens. I carefully pried out the ring with slight force using a pocket knife, inserted at the ends of the electric contact.
Next a ring is made from insulated electric wire, approx 1.6 mm diameter (I guess that would translate to about 14-16 AWG). This is to be fitted between the (moving) front of the lens and the UV filter, note that because of this a filter has to be used on the adapted lens. The wire will slightly limit the movement of the front lens, preventing us from zooming out to far. Note that the thickness of the wire is most likely dependent on the UV filter in use (in my case a B+W F-PRO), why you might need to select a thicker wire in order to ensure that the mirror does not hit the rear lens element.
That was all that was necessary in order to adapt the Canon EF-S 10-22/3.5-4.5 for use on the Canon EOS 10D, or the Canon EOS D60 that have the same type of mirror. As an extra finishing touch the plastic ring we removed can be replaced by one from the Canon EF 24-85/3.5-4.5, that have a perfect fit.
In this article I have shown that you can use the Canon EF-S 10-22/3.5-4.5 on the Canon EOS 10D, the next question is if it is viable. With the introduction of super wide angle lenses from Sigma, Tamron and Tokina you have to decide for your self.