What do I need to buy lens mount adapters?
Buying lens mount adapter allows you use one type of brand or lens on a camera for which it was not intended for.
For instance, Canon users can mount Nikon, Olympus, Contax/Zeiss, and others via the use of a lens mount adapter.
Why use a lens adapter?
No company has an absolutely "best" collection of lenses. There are constantly a small number of standout lenses in any lens lineup; being able to make of use of these lenses on your branded camera allows you to use those very best lenses, whatever the "best" currently is.
Landscape photographers or those who habitually use a tripod should ponder hard about the options: on a tripod a manually featured lens is often appropriate, and this opens up the prospects for results with the top lenses from any number of brands.
Canon EOS customers can use the Nikon-mount Zeiss ZF/ZF.2 line, but as of 2010, almost all of the entire line is now accessible in ZE (Canon) mount. However, a lens mount adapter allows the complete ZF line to be used on a Canon, so when you buy the ZF mount lens, it allows use on both Nikon and Canon body mounts, for those who own both brands, or if you may switch camera brands at later date.
When lens adapters do not work.
Nikon's new "G" series of lenses do not have an aperture ring; the aperture is now controlled electronically. Most lens adapters are simple mechanical devices, but some new adapters include electronic control for G series lenses.
In other cases there are mechanical obstructions. Some Leica R lenses have a protruding metal part that will hit the mirror of some DSLRs (Do not want!!!). Occasionally, this metal part can sometimes be physically removed by filing it off, other time it’s not worth the effort.
How many adapters I need?
It’s recommend that you purchase one adapter for each lens you want to use; otherwise you'll be continually substituting the adapter for another, and you'll need to keep two lens caps on you instead of one. With the lens mount adapter in place, you'll also need a rear lens cap too for the adapter to use.
Lens adapters differ widely in class. The most rudimentary ones are cheap aluminium of thin build quality which can lead to your lens not focussing to infinity or being slightly blurry on one side.
If you want to buy lens mount adapters, you have to be aware too, for the basic models, that they also have poor or no black coating which can flake off. Some of this flaked off paint can get onto the sensor and stay there too, which is another big no-no.
While the cheap adapters can be had for up to £50, none of them were up to the task. Some of them wouldn't even lock onto the lens properly, which means your lens isn’t being held onto the body correctly, with no positive click sound to ease your mind.
A good quality lens adapter is all metal. A lens mount adapter must be a robust and precision piece of hardware. This is extremely important when adapting a big and heavy lens. Finally, an even thickness of the mount is vital to especially with wide angle lenses, where the slightest change will blur one side of the image.