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Is the main difference price (i.e. the second route is cheaper I estimate) or are there functional differences?
Hi David,
You have to choose adapter based on what lens you want to use. Sounds easy, no? The two main groups of lenses you can choose between are the Olympus/Sigma/Panasonic lenses made for 4/3 system cameras (like the Olympus E series or the Panasonic L1/L10) and the rest of the lenses made for whatever else.
If you want to use 4/3 system lenses you should obviously by the panasonic 4/3 --> m4/3 adapter to maintain automatic functions.
If you want to use any other lens that can be used with the 473 cameras if mounted with an adapter you can choose the route you mentioned and use the Panasonic adapter plus an XXX - 4/3 adapter - or just buy one adapter for the lenses you find in the list. There will be no difference in functionality as everything will be manual (focusing and aperture control and light metering) in any case.
So, it is about economy (how many expensive/cheap adapters are interested in buying?) and ergonomics.
I do a combo of all this. Some lenses I know I'll use often get their own dedicated adapter, some lenses I know will see occasionally use only will be used with a cheapo "eBay" adapter in combination with the Panasonic adapter. Some lenses (rangefinder type) cannot be mounted with the Panasonic adapter at all as they need to sit close to the sensor.
hth somewhat, /Jonas
EDIT: I see I repeat some already communicated by Godfrey but leave it all here anyway.