Will phase focusing go the way of the dinosaur?
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From: Pete on 8 Jun 2010 17:17 On 2010-06-08 19:28:56 +0100, David J Taylor said: > "Alfred Molon" <alfred_molon(a)yahoo.com> wrote in message > news:MPG.2678a5d3672342c598c31c(a)news.supernews.com... >> In article <hui5uq$tvv$1(a)news.eternal-september.org>, David J Taylor >> says... >>> One lens move. Focus done. >> >> Under ideal conditions. But in low light or in the tele range also phase >> AF hunts for a while until it locks. >> -- >> >> Alfred Molon > > Tele works just fine on my Nikon camera and lenses. In situations > where phase-detect hunts before lock, contrast-detect will likely fail > completely. Phase-detect is more sensitive than contrast-detect in low light. I've been able to use it when Live View has reduced to snow. If the integration period of LV was increased to, say, 15 seconds (the human eye night-adapted integration period) then it would do better, but how many minutes would it take to find sharp focus? I hate to think. -- Pete
From: SMS on 8 Jun 2010 18:06 On 08/06/10 2:17 PM, Pete wrote: <snip> > Phase-detect is more sensitive than contrast-detect in low light. I've > been able to use it when Live View has reduced to snow. If the > integration period of LV was increased to, say, 15 seconds (the human > eye night-adapted integration period) then it would do better, but how > many minutes would it take to find sharp focus? I hate to think. Canon (and I presume all other D-SLRs with the live view option) does allow phase detect AF, kind of, with live view, and they clearly explain the trade-offs contrast detect and phase detect (without actually ever using those names). "http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=1766" What's rather amusing are the add-ons for phase detect AF that Ricoh used on the GX100, and that apparently Panasonic is planning for their Micro 4:3 cameras. So take out the mirrors and lose phase detect AF when you go to Micro 4:3, then put the mirrors back via an extra-cost option for phase detect AF. With enough add-on kludges, they may be able to make Micro 4:3 a compelling choice, at least in size, compared to a D-SLR, while they increase the total system cost with costly attachments and more expensive lenses.
From: LOL! on 8 Jun 2010 18:53 On Tue, 08 Jun 2010 08:31:39 -0700, Paul Furman <paul-@-edgehill.net> wrote: >Bruce wrote: >> On Sun, 06 Jun 2010 21:51:13 -0500, James Nagler >> <jnagler(a)spamproofed.net> wrote: >>> Every last DSLR photo posted by every participant of these >>> newsgroups using all brands of DSLRs has shown focusing errors. More often >>> due to having too shallow DOF but still compounded with poor auto-focusing. >> >> You have a point, > >No he doesn't. So speaks the self-appointed macrophotography "X-Spurt" ("X" the unknown quantity, and "spurt", a drip working under pressure) who couldn't do decent macrophotography if his life depended on it. LOL!
From: Outing Trolls is FUN! on 8 Jun 2010 18:55 On Tue, 8 Jun 2010 19:28:56 +0100, "David J Taylor" <david-taylor(a)blueyonder.co.uk.invalid> wrote: >"Alfred Molon" <alfred_molon(a)yahoo.com> wrote in message >news:MPG.2678a5d3672342c598c31c(a)news.supernews.com... >> In article <hui5uq$tvv$1(a)news.eternal-september.org>, David J Taylor >> says... >>> One lens move. Focus done. >> >> Under ideal conditions. But in low light or in the tele range also phase >> AF hunts for a while until it locks. >> -- >> >> Alfred Molon > >Tele works just fine on my Nikon camera and lenses. In situations where >phase-detect hunts before lock, contrast-detect will likely fail >completely. > >Cheers, >David Lies. The sensor can be ramped up in gain to focus in lighting conditions in which phase focusing (always dependent on available light alone) can't do a damn thing at all.
From: Outing Trolls is FUN! on 8 Jun 2010 18:57
On Tue, 08 Jun 2010 13:39:27 -0700, SMS <scharf.steven(a)geemail.com> wrote: >On 08/06/10 11:28 AM, David J Taylor wrote: > ><snip> > >> Tele works just fine on my Nikon camera and lenses. In situations where >> phase-detect hunts before lock, contrast-detect will likely fail >> completely. > >In the cases where contrast-detect fails completely there is too little >light to take the picture anyway. The flash is too weak and the pixels >too small on P&S camera with a tiny sensor. Also there probably is no >optical viewfinder to frame the photo in the low light. The failure of >contrast detection in those circumstances is doing the user a favor. > >Now if it's a ZLR or something like the G11 with an external flash, >where you probably could take the picture if you could focus, you could >always try manual focus. > >The bottom line is to not try to use contrast-detect AF in very low >light. Even if you can focus, the results will still suck. It would help if you had ever actually used any of these cameras. Then you wouldn't project your imaginary BS onto the whole world. |