Headline - DSLRs have imprecise focusing due to their mirrors

Started Apr 5, 2014 | Discussions thread
stevo23 Forum Pro • Posts: 19,053
Re: Let's not go down a path...

Ontario Gone wrote:

stevo23 wrote:

Would on-sensor pdaf work? It's hard to stick with cdaf for every instance as it can be slow.

This is something i have been contemplating for some time but haven't really talked about. I think on sensor PDAF should be free of parallax, afterall there is no change between light paths, there is only one light path.

Well, there are still two - just on the same plane, or very close to it and in a fixed position that won't shift or move.

Now not all lenses and cameras have this bad of an issue, but i decided then and there that since i could live without PDAF tracking, i would never deal with focus errors again. It's not like we MUST have AF anyway, there are loads of classics that were shot with MF. I can deal with limitations, i don't want to deal with inconsistencies.

But if you're relying on autofocus and you need something to work in every situation, a hybrid pdaf/cdaf approach is nice.

Depends on the speed of CDAF. A long time ago, i made a claim that CDAF would someday be the best. It's the way our eyes work too, once we sense the highest contrast, our brains stop focusing. We don't have cross hairs in our vision, we know when we are "looking" at something because that's the spot with the most highly concentrated cones on our retina. Same with focus, when we sense the sharpest view, the lens stops adjusting.

But right now, as I understand it, a camera like the A7 uses PDAF to get close and CDAF to finalize the focus state. This is where they put their money today...

I'm not unlike you in that I don't rely on autofocus for it's speed, so CDAF is great and doesn't depend on mechanical calibration or even which lens is connected for it's accuracy.

If somebody could make CDAF that has a processor and software that could simply think faster, it would improve.

Yes, that is what it would take. But then that processing could also be used to improve PDAF even that much more since it's needs are very simple.

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