FT-lenses om MFT. Why do they not work properly?

[frode_inge_helland]

<p>I bought E-P3 and was diappointed how feeble the autofocus worked with FT-lenses.<br>

I do not understand why this has to be the case. The MTF is based on contrast detection, and FT on phase detection. Both systems results in a flow of signals from the camera to the focus engine in the lens. <br>

The FT lenses DO work om MTF, but sluggish and often not spot on. Why?<br>

I's hard to understand is that the signals from the contrast detection cannot be transformed to signals corresponding to the phase detection signals, so they make the FT lenses work optimally on MTF.<br /><br /></p>

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[GerrySiegel]

<p>Olympus says they are working on a way to get them to work better together. Like the ranchers and the farmers can be friends so why cannot the two systems be interoperable without this sluggishness we all got to put up with, no mystery in the tables of what goes with what, but the question of what the design challenges are, I don't know and am not sure I would understand if I were told. I would try however. The question is now on the floor....Discussion anyone. Is there an optical engineer in the house? An engineer, any kind even sanitary? Well read technician? Someone in the sales business who has kept up would be ok. Interesting one Frode. I never thought to look into this business and just took it on faith. But why should we after all. And if there is a fix on the way, will it be by an adapter, software or firmware or a full court press, and one more investment in a new whole body variant ?...<br>

(Now what have wizards of Sony come up with in their new mirrorless system vis a vis legacy lenses from their conventional cameras, if any one can invent a way it will be Sony I betcha...)</p>

[Greg M]

<p>There are obviously contrast and phase detection system issues for everyone. Read any review of any DSLR that offers live view shooting via the back LCD. There's always one similarity in every review from brand to brand and that is, AF is slower in live view and contrast AF than used with phase detection AF and the optical finder. Got to DPReview and scan reviews of the latest DSLR's like the Nikon D800 or D600. Anytime Live View is enabled with contrast detection AF, focus speeds are slow. What you are experiencing is just the technology as it exists today.</p>

<p>It is what it is, and it's not just an Olympus problem.</p>

[bruce_rubenstein]

<p>The most probably difference is the AF motor used in the lens (nothing to do with optics), and the way that the two AF systems work (not determine AF). A PDAF system calculates the distance to the subject and then drives the directly to that point, performs a focus check and touch up as necessary. It's a hybrid open loop system. A CDAF system moves the lens and constantly checks contrast. The contrast continues to go up until it goes past maximum contrast and then goes back to best focus. It's a closed loop control system. Stepper motors, which move in a fixed rotational amount for every signal pulse, work much better for CDAF. To get other types of motor, used for AF, to work well with CDAF, the lens has to be driven at low speeds. It's the same reason DSLRs focus so slow in Liveview mode.</p>

[frode_inge_helland]

<p>Bruce, thank you. I see.<br>

Is there a hope that the next OMD will fix this problem more satisfactory? I read some rumors that Olumpus was working on an adapter with a fix, translucent mirror to cope. <br>

To me this seems less likely now.</p><div></div>

[bruce_rubenstein]

<p>A translucent mirror would suggest a separate AF sensor array needed for PDAF. I wouldn't anticipate Olympus making AF work well with 4/3 lenses on µ4/3 bodies unless it cost very little to add. Very few people with µ4/3 bodies have 4/3 lenses.</p>

[GerrySiegel]

<blockquote>

<p>Very few people with µ4/3 bodies have 4/3 lenses.</p>

</blockquote>

<p>"Include me in." I own two G.. Lumixes and at least four 4/3 lenses plus teleconverter. They all work fine and fit the sensor size but it would be really fitting and nice to have faster, even some faster than current slogging speed autofocus, a gift if you like to us owners of the lenses which we bought for the full size 4/3 and still does fine job on those models. No obsolence here so I call it a bonus gift... The 50-200 mm for instance would be hard to see replicated in a micro lens, it is a gem, and its tripod barrel support makes it most usable with micro cameras. Especially mated to the larger size video hybrid type cameras like the new GH 3. The same for old 50mm F 2n a nice macro style lens in right focal length to be all purpose... This seems to be the only palatable development path open actually,- not reading rumor speculations or wishful thinking chatter- but just official press release (like Greek oracles they speek in tongues and all) blather we have to decode but no time for all that while living a life of activity....<br>

Something <em>will</em> get addressed. It can't be insoluble for the marketers if they get around tuit...( I bet no money yet until my wife's hairdresser ()-) discloses Oly's immediate plans for the one integrated system thing,whatever it will be. We can wait it out . Or not, no biggee)</p>