How is the OMD so fast

Started Jan 7, 2013 | Discussions thread
papillon_65 Forum Pro • Posts: 27,030
Re: How is the OMD so fast

AndyGM wrote:

papillon_65 wrote:

It is CDAF only because all m4/3's lenses are designed for CDAF focusing. Combining CDAF and PDAF on a sensor is a kludge which means that you are forced to use larger lenses which are designed for PDAF.

Well, you are not forced to use large lenses when combining PDAF and CDAF, that is incorrect. With a hybrid system, CDAF is still used for part of the focusing (usually for a final accuracy check) so everything you say about small lens elements that have to be able to move back and forth fast still applies. PDAF does not mean big lenses, look at the Nikon 1 system. Should an m43 camera get hybrid PDAF/CDAF in the future, the existing small CDAF optimised m43 lenses should still work with it, so the ability to track subjects moving toward or away with continuous AF should improve for the m43 system as a whole.

You are if you want to use a fast longer telephoto lenses, because these will invariably be large due to the amount of glass required. Unless optical design changes it's unlikely you will ever see a small  fast sports lens with decent reach that will use CDAF focusing. The 35-100mm F2.8 is about as good as it's going to get for a small camera unless you use a larger camera body. You're then into GH3 territory and you may as well use a DSLR IMHO.

The other advantage is the camera can switch to a PDAF only mode when used with adapted lenses that were only designed for PDAF, like the Four Thirds system lenses. The intention of doing this is not to stop m43 lens development because we will be expected to just use the larger Four Thirds lenses that already exist. The intention is to give existing Four Thirds camera body owners an upgrade path where they can continue to use the Four Thirds lenses they already have (and that were usually bought at great expense).

Lenses like the 12-60mm and 50-200mm are just too large to be used comfortably on a camera like the OMD, I know, I've tried it. Even with PDAF speed focusing I wouldn't want to use these lenses on m4/3's. This system is all about size reduction for most people.

I believe that CDAF systems will overcome this with time though it doesn't bother me personally. So while other systems will enable you to use pdaf you lose the size advantage of the smaller lenses, so why not just use a DSLR instead?

I really don't think this issue of at least knowing if the subject is moving toward or away is ever going to be overcome with CDAF, as Paul has explained in a later post. Hybrid CDAF/PDAF for m43 is therefore not a kludge, its an inevitability.

If you have to choose between two different focusing systems to achieve the same thing it's a kludge in my book. The ideal focusing system would do it all on an m4/3's sized or similar camera.

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