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Converted to EF Mount

On Dec 20 2005 I converted my lens from an EFS mount to an EF mount. Thanks to Rich Cutler who explains this procedure nicely here http://forums.dpreview.com/forums/read.asp?forum=1029&message=15346329. I tried it on the 17-85IS and it went very smoothly. It took me about 15 minutes to do, although I think I could do it now in about 3 minutes. It is quite easy, but if you choose to do it to your EFS lens, you do it AT YOUR OWN RISK.

*For the 18-55 EFS conversion to EF mount, see http://www.devilgas.com/photo/efs_surgery/efs_surgery.asp
Before
Before		 During
During		 Done w/o EF Baffle
Done w/o EF Baffle		 Done w/ EF Baffle
Done w/ EF Baffle

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lightrules 27-Feb-2007 07:37
Jim, just so you know, I don't recall the EF baffle size of the 1755IS. The conversion shown here is for the 1785IS, and I am pretty certain they have different baffle sizes. So take this into account. Also be sure to check your mirror clearance on whichever body you put the 1755IS to with this "EF mount" conversion.
Jim yeager 27-Feb-2007 07:12
Thanks. My 17-55 2.8 IS is now an EF lens. Works great.
lightrules 27-Feb-2007 00:53
See my comments here http://www.pbase.com/lightrules/image/53787969/original
Jim yeager 26-Feb-2007 21:03
Where did you get the EF baffle?
lightrules 14-Sep-2006 15:19
The Tokina 1650 is not available as of yet. I look forward to trying it out.
Christophe 14-Sep-2006 06:45
If ever you know anything about it, just tell us please !

If I understand, you choose the tokina ?!? How is it ?
lightrules 13-Sep-2006 21:33
No, I never tried it on the 1755IS. I don't recall how far out the rear element protrudes on this lens, so I can't tell you if it would work or not. My hunch is that it would be fine on a 10D with the conversion, but I can't say for sure. Good question though.
Christophe 13-Sep-2006 19:50
Hi Jojo,
when I have contacted you some time ago you where about to try the conversion of the 17-55, did you do it eventually ??? (I still have my 10 D !)

Thanks for info
lightrules 11-Mar-2006 05:22
Thomas, Canon EFS and Sigma DC lenses are all designed to only work with 1.6x bodies due to their smaller image circles. Sigma DG lenses work with both FF and crop bodies. And though my 1785 has been converted to EF mount, it will still only "work" on a crop body. In this sense, it is like Sigma's DC lenses now; however, even still, not all EFS to EF conversions (e.g., Canon 10-22) entail proper functioning since certain lens/body combinations may have mirror interference issues still.
Thomas Snaaijer 11-Mar-2006 00:02
Very interesting 'workshop'. Makes you wonder if this can be done with Sigma's DC or DG lenses as well? But don't the EF-S lenses have smaller image circles (since they're not made to perform on anything larger than 1.6x crop) therefore rendering them useless (or at least, not as useful) on anything other than 1.6x crops? I could be wrong here...
lightrules 27-Feb-2006 14:25
That's excellent stuff. Now we'll see who is the first to try the new 1755IS to EF mount. Enjoy and try not to shoot at 18mm too much.
bolantej 27-Feb-2006 07:47
Hey FstopJojo thanks for the link. I performed surgery on my kit lens and swapped the whole mount with the kit lens from my Rebel T2 (28-90). I get some vignetting at 18mm, and what seems like mirror tapping at 18mm as well. The rear lens element sticks out a little. Kind of a long shutter, and the low battery indicator blinks, until I hit the release a second time. When I zoom out to 19 1/2 or so, it seems fine. I'm gonna post this elsewhere, as some might be interested.

Peace.
nsr 15-Feb-2006 23:48
yes i would be scared out of my mind of smashing a full frame 5D mirror into the rear lens element on my EF-S lens
innes 30-Jan-2006 11:51
Or a mirror-hitting-lens-a-rama, come to think of it...
innes 30-Jan-2006 11:44
It'd be interesting to see the results you get attaching the lens to a ff camera. Presumably vignetting-a-mundo.
lightrules 30-Dec-2005 15:51
I am not aware of anyone trying this conversion with the 10-22. However the physical tolerances with this UWA lens are very tight so there would have do be some very precise measurements done beforehand. As for the 1785 IQ, that is not affected; nothing optically was altered. Lastly, yes the original EFS baffle can be easily re-inserted. Read the DPR link above to see how it is all done.
AlpineMan 30-Dec-2005 14:56
Sorry for the multi-comment...I'm assuming there's no loss in image quality as a result of this retrofit? In case the lens needs to go to Canon for warranty repair, can the replacement EF baffle be easily popped out so you can put the original EF-S baffle back in? I wonder why the heck Canon didn't just use an EF baffle in the first place?!
AlpineMan 30-Dec-2005 14:52
Has anyone tried this on the 10-22mm lens? Will the same baffle fit on this lens?
lightrules 29-Dec-2005 18:34
Very good comment. I completely overlooked that benefit as well. I just tried the lens with my ETs and it works perfectly. So yes, converting this lens to EF mount allows for use with ETs.
Paul 29-Dec-2005 17:49
omg does that mean extension tubes for EF lens could now be used? that'd be so sweet! Thanks for posting the photos!
lightrules 29-Dec-2005 05:19
Not sure I understand your question, but the reason why I (and others) did it is because it allows the lens to be mounted to non-EFS bodies (e.g., D60, D30, 10D). The bottom line is that it isn't as limiting and body-specific as it once was.
David 29-Dec-2005 04:46
This is certainly a DIY achievement but why do you want to do it? What is the use of a EF-S lens on a Canon that accepts normal EF lens only?
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