As shown in the picture above, the flange thickness on a Canon / Leica-R adapter is ~3mm. This is over 2X thicker than a Canon / Contax adapter, so the Canon / Leica combination is more forgiving. Most Leica R lenses fit on a Canon EF or EF-s dSLR camera body without any problems (via adapter of course). However, there are some exceptions to the rule, such as the Leica 21-35mm ASPH, 19mm F2.8 Elmarit ROM and several others. These specific lenses require an added degree of commitment. 

Leica Wide Angle 21-35mm F3.5 ASPH Vario-Elmarit-R (available at B&H Photo)

The following applies to the Canon 1Ds, 1Ds Mark II, 1Ds Mark III, 5D, 1D, 1D Mark II, 1D Mark IIn and 1D Mark III

The Leica 21-35mm ASPH is a simple and quick solution. The plastic shroud at the rear of the lens interferes with the Canon mirror. Three small jewelers screws hold the plastic shroud in place - unscrew them, remove the shroud, put the screws back in place for safe keeping. The entire process takes less than a minute with the proper screw driver and is 100% reversible with no ill effects. The shroud is a cosmetic piece (probably intended to protect the lens’ inner workings from dust and debris), removing it has no effect on the lens’ operation or performance. We have received feedback that even with the plastic shroud removed, the Canon 5D may still have issues (the database has been changed from “S” to “I” for the Canon 5D).

Leica Zoom Wide Angle Tele 28-90mm F2.8-4.5 ASPH Vario-Elmarit-R (available at B&H Photo)

The following applies to the Canon 1Ds, 1Ds Mark II, 1Ds Mark III, 5D, 1D, 1D Mark II, 1D Mark IIn and 1D Mark III

The 28-90mm has a similar looking shroud as the 21-35mm; however, there is a small spring held in place by the shroud. Removing the shroud releases the spring which can lead to problems. Big problems! We have received conflicting reports with one person successfully removing the shroud without losing the spring and worked some magic to keep the spring in place. Another person said he removed the shroud and the spring popped out and the lens had to go to Leica for repair. PebblePlace.com does NOT recommending removing the shroud. Some owners have decided to accept the risk -

1. •APRIL 8, 2008 UPDATE:  There have been occasional reports of the 28-90mm working on various Canon bodies, such as an email on April 8, 2008 indicating the combo worked fine on a Canon 1D Mark III. If you already have the lens and an adapter, then give it a try - maybe you will be one of the lucky ones. To see if there is any consensus, I started a thread in the user forums.
   

2. •Please exercise caution with the 28-90 ASPH. Due to the contradicting reports it’s not possible to give the lens a 100% “YES” or “NO”. We do NOT recommend removing the protective shroud on the rear of lens since that could led to down-time and repair expense.
   

I encourage readers to use the PebblePlacePhotography.com forums. The reason for the forums is so fellow-photographers and add their own comments about specific Leica lenses and adapter / Canon dSLRs combo’s. There can be conflicting information - and most of scattered across the web in tiny little forum posts here and there.

Our forums will never be big. We just want very high quality information there so other Leica lens users can refer to this site and accompanying user comments and make informed decisions. The 28-90mm ASPH has worked for some, and not for others. It is an ideal candidate for a forum discussion.

Leica Super Wide Angle 19mm F2.8 Elmarit R (Second Version) (available at B&H Photo)

The following applies to the Canon 1Ds, 1Ds Mark II, 1Ds Mark III, 5D, 1D, 1D Mark II, 1D Mark IIn and 1D Mark III

The second version Leica 19mm F2.8 Elmarit-R requires extreme “surgery”. The second version is the one you want - and it costs much, much more than the original 19mm. The original 19mm is probably a good lens for the 19mm look, but if want corners - as in sharp corners --- then you want the SECOND version.

Some owners have modified the 19mm Elmarit’s rear housing by grinding it down approximately 2mm. Not the entire rear housing has to be ground, just lower half which catches the mirror as the mirror swings up. If you want to learn more about this, check www.fredmiranda.com “Alternative Digital Systems & Lenses” forum. For this particular lens modifying the Canon’s mirror may be a better option. The earlier 19mm F2.8 Elmarit does fit the Canon bodies without modification.

If you have read a couple pages thus far, then you have probably determine PebblePlace.com is a pretty conservative bunch. We try to be. We’ll present the information, make the “safe” recommendation - and then the reader can decide just how far they are willing to go. In the case of the Leica 19mm Elmarit - the safe route is buy one which as already been modified. Then do come up from time to time on Ebay on FredMiranda.com. Let somebody else take the risk - and you enjoy the benefit. So in case you missed the warning - PebblePlace.com does NOT recommend grinding your lens into the ground!

Leica 35mm Summilux (available at B&H Photo) and 24mm Elmarit

The following applies to the Canon 1Ds, 1Ds Mark II, 1Ds Mark III, 5D, 1D, 1D Mark II, 1D Mark IIn and 1D Mark III

These lenses simply do not fit and lens modification is not possible. If you are willing to shave the mirror on your 1Ds or 5D, then maybe. Such as the 19mm Elmarit, these are extreme measures not recommended. If you would like to learn more, again, try www.fredmiranda.com “Alternative Digital Systems & Lenses” forum.

Another option - the easy option - is a Canon 40D or similar. The EF-s bodies have smaller mirrors, so there are no clearance problems. Normally I do not like a cropped-body dSLR, full-frame is my preference. However, a 35mm Summilux can be a great walk-around lens on a 1.6x body.

In regards to the 24mm Elmarit, looking a 28mm F2.8 Elmarit-R instead. The current version (its hood is built-in) is supposedly spectacularly sharp wide open and just better and better as its stopped down.

Updated June 6, 2008