• The converter adapter ring with mini shape which is convenient to use and pack up

How to Choose Adapter Ring?

• First of all you have to buy the appropriate physical lens adapter required to get your lens attached to your camera. For this you should consult your favourite camera shop . But a number of manufacturers build simple metal ring adapters that let you attach various types of lenses
• If you've got, for example, a lens designed for an old Pentax threaded (screw mount) camera like the Pentax Spotmatic you'll need an adapter for M42 lenses. Same with the new line of Carl Zeiss ZS lenses, which also use M42. If you have a telescope you'll probably need a T-mount adapter, assuming your telescope has the ability to be hooked up to a camera at all. Or if you have a Nikon lens you'll need an adapter that lets you fit Nikon F lenses to your EOS body. Likewise Leica R, Leica Visoflex, Olympus OM, Contax/Yashica RTS, Rollei, and Contax manual focus, or even big Hasselblad, Mamiya 645, Pentacon 66, Pentax 645 and Pentax 6x7 medium format lenses can all be adapted. Microscopes apparently often require C-mount adapters. Tamron built a series of Adaptall II lenses and you can still occasionally find used Adaptall II->EOS adapters around. I have links to some sources for these adapters at the end of the page
• Most adapters are simply metal rings with an EF bayonet on one side; And since the EF mounting ring is larger in diameter than most 35mm SLR lens mounts quite a few lenses can be adapted to the EOS system

Adapter ring compatibility problems and infinity focus:

• The most common problem is that of lens registration - the distance from the lens mount to the film plane. It may not be possible to build a lens adapter that gets this distance right for certain lens mount systems
• For example, the back focus distance (distance from the rearmost lens element to the film plane) on EOS cameras is 44mm, but on Leica rangefinder cameras it's 27.8mm. Matching the back focus distance would require a lens mounted deep inside the camera body; not usually an option. In cases such as this you may either have to buy an adapter ring that won't let you achieve infinity focus or you'll have to get an adapter ring which contains one or more glass lens elements and which will inevitably degrade the image quality somewhat. These compensating elements let you achieve focus to infinity, though at the expense of image quality. Contax G, Konica F, Leica M, MD and Miranda lenses are other lens mounts with back focus distances less than that of Canon EOS
• There is also the case of lenses which have lens register distances very close to that of a true Canon EF lens. Contax/Yashica lenses (45.5mm) and Canon EF lenses (44mm), for example, have only a 1.5mm difference in lens registration, and 1.5 is awfully thin for a metal ring adapter. Such adapters have to be machined to incredibly close tolerances in order for infinity focus to work, which means they can be quite expensive. Cheaper ones often have to be sanded down to maintain infinity focus - but even that is something of a dodgy proposition as you have to sand the surface down accurately from one side to the other, down to a fraction of a millimetre
• Also appears that it isn't possible to make adapter rings that let you mount Pentax K (bayonet mount) lenses on EOS cameras with EF lens mounts. The Pentax K diaphragm coupling lever physically interferes with such a possibility. So you'd have to modify the lens (or the camera) to make such a conversion possible. Note that this does not apply to cameras compatible with the EF-S mount. The design of the EF-S mount, with its smaller mirror box thanks to the 1.6x crop factor, coincidentally permits the use of such lens adapters
• Finally, and this isn't strictly to do with manual focus lenses per se, but you can't use Vectis or Four Thirds (Olympus, Kodak, Fuji, Sanyo, Sigma, Panasonic and Leica) lenses on EOS cameras. These lenses, in addition to being autofocus lenses, cast very small image circles; much too small to cover the imaging area of EOS cameras. In theory I suppose the Vectis lens design might cover an EF-S sensor, but it would probably be pointlessly expensive to make such an adapter

• 1 x MD/MC Mount Lens Adapter Ring for Canon EOS
• 1 x Front Lens Cap
• 1 x Rear Lens Cap