Gordon Laing wrote:
Hi Peter, welcome to the forums!
Good grief! - have I got this right? Are you really using the EF-S 10-22mm on a 1D Mark IIn? I knew there'd be issues concerning edge quality and the mirror potentially hitting the rear element, but I thought the ultimate problem would be a physical incompatibility when actually mounting the lens on the body bayonet!
I must admit I've never tried fitting an EF-S lens to one of Canon's 1.3x crop bodies like the 1D Mark IIn, but I do know they physically just won't even mount on a full-frame body like the 5D.
If they do fit on the 1.3x bodies and the results are ok, then that's a really nice modification! Although I note 1.3 times 12mm gives you close to 16mm, which is the same as 1.6 times 10mm, on the proper EF-S bodies. Still, as you say, the official alternative from Canon (16-35 / 17-40) aren't as wide.
Please do post photos of both the lens mounted on the body - and of course some shots taken with it!
You are correct ..normally there's no way to attach an Efs lens on a 5D,1D or 1Ds. The reason why is not caused by the lensmount(bajonet) though, its because the sealing cap near the rear element is larger than that of a normal Ef lens. If you try to mount it the plastic cover hits the inside of the mirrorchamber before the bajonet can connect. I removed this piece of plastic an replaced it by one from a broken(beyond repair) Ef lens. After this you CAN attach an Efs on a non Efs body. But at this stage it would not be very wise to do so, because the rear element also is a bit larget than a normal Ef lens at the 10-11.5mm setting .It hits the mirror at the widest end. To safely use this 10-22 you need to block the lens from zooming further than 12mm.I did this by glueing in a 3mm ring just behind the filterthread near the frontelement. Now its possible to use the lens safely between 12-22 mm. The ring blocks the lens from zooming to the widest end.
The 1.3crop bodies from Canon are in fact all 1.25 crop bodies. I think they just use 1.3 for an easyer calculation for focal lenght. A 30D is not a 1.6 but a 1.58 crop. I only found out about that when i compared the photo's from the 1D body with this lens at 12mm and a photo from a 30D with this lens at 10mm. Its a lot wider on the 12mm setting on a 1D. ( 1.25x 12mm = 15mm in 35mm format).
The lens does not distort or soften the corners more than when used on my 30D. I found it performed even better than the 17-40L that i bought to use on my 1D.....and its a lot wider.(maybe i bought a bad copy 17-40mmL). There's is a downside though...when i put a slim polarizer on this lens i get vignetting. Once past 13.5mm there's no longer vignetting.
Here's a photo with the 10-22 on my 1D body.http://farm2.static.flickr.com/1087/1001781890_cfebd09c36_o.jpg
Here you find two photo's taken with this Efs 10-22 on a 1D at 12mm