Headline - DSLRs have imprecise focusing due to their mirrors

Started Apr 5, 2014 | Discussions thread
mosswings Veteran Member • Posts: 8,217
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. Unless the camera actually measured the distance wrong from the start, it should be accurate. This is why when people complain about on sensor pdaf having FF/BF, i think they are mistaking it for something else, perhaps slight movement of their subject, or the AF box didn't lock to what they thought it did. FF/BF arises because there are two different light paths that end up being slightly different in length, this doesn't sound possible with cameras like the EM1 because it's all on the same plane, the sensor.

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.

If somebody could make CDAF that has a processor and software that could simply think faster, it would improve. Im not sure how well predictive motion will work out, perhaps algorithms are needed for that. We shall see how the new GH4 pans out. We will see soon, but i find it hard to believe if it's a junk system, Panasonic wouldn't have realized half way through "hey guys this just isn't working, lets not spend another 4 million $ for a flop". Im guessing it will surprise a lot of people, perhaps even change the way other brands look at AF.

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"Run to the light, Carol Anne. Run as fast as you can!"

Check out various posts in the Photographic Science forum, including this recent one:

http://www.dpreview.com/forums/thread/3649822

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