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Canon EFS to EF lens modification

Canon EFS to EF lens modification

Shopping objectives to your digital SLR camera can be pretty expensive. Price and quality tend to go hand in hand when you are talking about optics and you do not want to use the low quality lenses on your expensive camera if you can avoid it. But what to do when you can not afford to buy that new L-class lense from Canon or the cheaper lines does not offer you that wide angle you want?
Now that Canon have introduced its new lineup of digital SLR cameras they also introduced a new kind of lense. The new EF-S that the 20D, 300D and 350D uses, introduced a bit different design that we had seen on previous lenses. S in the EFS stands for “Short back focus”, meaning that the rear most optical element is closer to the imaging sensor of the digital camera. It has some advantages over the older EF system when dealing with wide angle lenses.

Canon introduced some pretty sweet lenses to the EFS system when they introduced the new 300D and 20D digital SLRs. Especially the 18-55/3.5-5.6 kit lense. As it was a kit lense, the only way you could get your hands one was to buy one of these new cameras or search for the kit lenses on eBay. Prices of these lenses are around 100 dollars (80-90 euros) which makes them very interesting.


Now the nasty part. While the EFS lense in general would work with EF cameras such as Canon 10D and D30 without problems, Canon decided to make the lense non-compatible with them. As you can see from the image, the lense on the left (EFS) have a protrusion around the optics part that isn’t there on the regular EF lense that is on the right. This to make sure that the lense can’t be attached to an EF camera that doesn’t have the proper clearance between the mirror and the lense optics. 10D does have a proper clearance and so does D30 (D60 too should work) and this brings us back to the mod we are about to do.

As radical as it seems, we are going to remove that protrusion by force. Well, perhaps not with a brute force but the process does involve saws or power tools. Is this safe? Yes and no. The mod itself it relatively easy to do and safe but as always there are tons of different unexpected things that can go wrong. Or in the end you stick this lense to an EF camera that doens’t have a proper clearance between the lense and the mirror and your camera will get damaged. Just make sure your camera is indeed on of these smaller imaging sensor versions (10D, D30 etc.) and follow the instructions and you should be safe. At least my camera (10D) worked great with this lense after the mod.

There are several ways to make this mod and I will be showing the method that preserves the center ring. Meaning that I don’t just take a hacksaw and make the cut. Some people have done it this way and have produced a working lense but as I said, I prefer the more “professional” approach. For this you will need some very small phillips head screwdrivers. Also some epoxy and sanding paper are needed.

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