I have read on this forum in several spots that adapted 4/3 lenses do not focus as fast as the standard m4/3 as a result of differing focus detection type.

When you guys are saying slow, I get that it is not as fast but how can I relate it to my Panasonic GH2 w/ 14-42mm lens? Are we talking it takes an extra second or several seconds more, or something like I can manually focus it faster?

I got the Panasonic 4/3 to m4/3 adapter for Christmas and am now looking into getting a 4/3 lens, I am thinking the 70-300 F4-5.6 ZUIKO ED. I can't quite afford the m4/3 lens in the same, so this is my best option with out falling back on totally manual Nikon lenses (I have a Voigtlander adapter for my old Nikkor lenses).

Also, the automatic apeture and EXIF info still work fine on the 4/3 lens, right? Its just the focusing that slows?

Thank you,

Matt

I bought the Zuiko 70-300 and used it with an adaptor on my Olympus Ep2. I don't know how fast it is on 4/3 bodies but for me it works well and I'm very happy with it. I didn't meausure AF speed and never do it anyway but it's fast enough for non professional use. So buy it and you'll have a great focal lenght with a very good lens. It will keep full automatic features, at least it does on my Ep2. Tomorrow I'll try it on the G3 but remember it has no built in stasbilization.

I wouldn't describe any 4/3 lens as fast focusing on m4/3 cameras. Some are okay but they'd still be described as slow by any measurable standard. Some are truly bad (1 sec +); examples being the PL 14-50 f2.8-3.8, Zuiko 50-200mm f2.8-3.5, Zuiko 9-18mm f4-5.6, Zuiko 18-180mm f3.5-6.3.

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Nic
E-M5, GH1
Flickr Photostream
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You are absolutely right if measuring in absolute terms and measuring the AF speed in terms of time, but that does not mean it would not meet user needs. Of course 1+ second speed is not the best you can have, but if can compromise with it and don't have particular needs like sports or action ecc., well you can live with it. Obviously thats my personal ad subjective opinion, so I can use, and use, the 70-300 without flaws, if I need something faster I'll use another lens, but then the cost is not the same.
I think it comes to what is a reasonable compromise for the use and money we want to spend. I don't think you use the 4/3 70-300 all the time in a m4/3camera (at least that's what I suppose, also because it's really huge and with the adaptor it's even bigger) so for those few times I use it I can live with the not lightining fast AF. IMHO
I also have the 35mm macro and it's slow, very slow, at times on my EP2, but doing macro of still things I can cope with it, of course getting insects (moving objects) would be a bit harder
So my advise is: try it if you can then decide if it is ok for you.

I've used the 70-300 on my E-5, E-620 and E-PL2. And while it's not a Speedy Gonzales on either format, it seems to focus just as quickly on the E-PL2 as it does on the two 4/3 bodies.

I think that may be because Olympus made it specifically to work with both PDAF (used by 4/3 through the viewfinder) and CDAF (used by m-4/3). But whatever the reason, there doesn't seem to be any difference in AF speed between Olympus 43 and m-43 bodies.

It (plus adapter) is much bigger than the m-43 native lenses that reach 300mm, but it's not heavy. The optics are teriffic, so it delivers great images with either format. And as you point out, it's considerably less expensive than the native m-4/3 varieties.

It's not a blazingly-fast focus lens even on th E-5, but as elandel says, it's fast enough for non-professional use. So go for it... You'll probably be very happy unless you're shooting motorsports or model airplane dogfights. Even then, you'll still be able to get some nice shots of those subjects with good technique and enough practice, imho.

BTW -- You almost certainly will need a monopod, tripod or some other support with it at the long end, so plan for that in your budget, too.

Most off all.... have fun shooting!

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Peace,