E-7 confirmed and possible E-720...

Started May 29, 2012 | Discussions thread
dave gaines
Veteran MemberPosts: 9,008Gear list
How would 4/3 benefit from a hybrid PDAF/CDAF?
In reply to Rriley, May 31, 2012

Rriley wrote:

dave gaines wrote:

... about the Nikon 1 system. ... The hybrid method of focus is controlled by the camera, not the user. To operate in PDAF mode it requires very good light or fast apertures - f/2.8 or better.

typically lenses are held wide open during focus movements

And exposure too. But the Nikon 1 lenses are slow except for the 10mm f/2.8 pancake. So PDAF only works with the WA pancake (27 mm EFL) or in very bright light.

Thom Hogan had a series of images using the camera for BIF, and it seemed to work out. But there is a question over its low light performance where it reverts to cdAF.

Not that I'm interested in a Nikon 1, I'd like to read the article. But yea, it may be okay for white owls in the daylight. Everything else uses slow CDAF, which is no good for things that move.

I'm of the view that things can be done about this, but it requires the capacity to engineer different pixel covers for AF pixels on the bayer layer. Nikons 1 doesn't do any of that, it uses a simple bayer layer and as a consequence is more light limited.

It requires a sensor at 40 mm (38.5 mm) from the flange/lens. DSLRs currently do this via mirrors, beam splitters and PD sensors.

Can you explain how this hybrid works and how it would apply to a m4/3 body using both m4/3 lenses and 4/3 HG and SHG lenses with an adapter? How would it function with these lenses interchangeably?

And why would we want this? The m4/3 lenses don't used PDAF, just CDAF. Oly ZD 4/3 lenses require PDAF to focus fast and an adapter on a m4/3 body. CDAF can be more accurate but it is too slow with the existing 4/3 lenses. Small m4/3 bodies aren't well suited for large lenses. A DSLR like the E-5 is the right body for HG and SHG lenses. Why try to combine systems with a hybrid just to use 4/3 lenses on a m4/3 body?

A 4/3 lens adapter could incorporate PDAF if the flipping mirror could be housed in the adapter. ..

We dont have 20mm to play with, and the only other version of this is Sony's SLT adapter. After the mFT register distance is subtracted there is 18.58mm vs Sony's 26.6m, ...

Possibly, but why would we want this? I'm going to look at the mirror boxes in my E-5 and E-330 to see how far below the flange the mirror sits.

And as soon as you introduce a mirror in the light path you need another sensor to provide an EVF, similar to how the E-330 works. There's no OVF with an adapter on a m4/3. And how would you sync the 2nd sensor with the EVF already in a m4/3 body? Or on the LCD in live view? You only have 9 pins on the m4/3 flange. Back to the future, a Pen with a plug in EVF?

... is it a sign that after 4 years they have failed to make an Exxx replacement in mFT ?

These are two different animals. E-xxx is an entry level DSLR. Micro 4/3 is a MILC. The OM-D EM-5 is not an entry level camera at $1300 with grips.

We can only judge what is available today. We have an E-5, the E-P Pens and an OM-D EM-5 to choose from. Speculating on what might be possible is just wishful thinking.

 dave gaines's gear list:dave gaines's gear list
Olympus C-8080 Wide Zoom Olympus E-330 Nikon D800E Nikon AF-S Nikkor 70-200mm f/2.8G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED +8 more
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