Photography The Sony Alpha Thread V45!, The Orange Legion
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 Aug 25 2010, 02:15 PM
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All Stars
15,856 posts Joined: Nov 2007 From: Zion   
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hahahha. all kena pour cold water. which is quite true. anyway my more realistic hope is that a550's price will drop like crazy!
on the hand, can some sifu explain to me what is phase detection AF all about? why is it better than contrast AF?tried to google but still don't understand.  in layman's term if possible! thanks!  |
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Aug 25 2010, 02:53 PM
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Elite
2,540 posts Joined: Mar 2008 From: KL
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QUOTE(zstan @ Aug 25 2010, 02:15 PM) on the hand, can some sifu explain to me what is phase detection AF all about? why is it better than contrast AF?tried to google but still don't understand. in layman's term if possible! thanks!   |
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Aug 25 2010, 02:56 PM
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Senior Member
6,633 posts Joined: Jan 2003 From: www.kelvinchiew.com
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aaa a550 price already drop lo..so sayang i bought expensive thing
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Aug 25 2010, 03:12 PM
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Senior Member
4,053 posts Joined: Jun 2009 From: Kuching
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Aiyo ... Everything also will drop price. Takkan u dont wanna buy.
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Aug 25 2010, 04:23 PM
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Senior Member
3,461 posts Joined: Feb 2007 From: Kota Kinabalu, Sabah
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Difficult to explain phase detect AF & contrast AF difference. This link may help:
http://en.wikipedia.org/wiki/Autofocus With contrast AF, the camera basically has to hunt and continuously compare contrast to get the best focus. That is why you will see the AF goes from blur to sharp, then become blur again, before finally become sharp and nailing the focus (this is when you hear the focus confirmation beep). This is most obvious in PnS cameras and handphone cameras. However, with phase detect AF, the AF module can know instantly if the subject is in front or behind the current focus point. It will also know HOW FAR away is the subject from the focus point. This gives the camera added information and enables it to quickly nail the focus. For moving subject, the AF module can even tell how fast the image is going out of phase, and in which direction (going back or going front) hence can predict the focus point. |
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Aug 25 2010, 04:55 PM
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All Stars
15,856 posts Joined: Nov 2007 From: Zion
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QUOTE(kysham @ Aug 25 2010, 04:23 PM) Difficult to explain phase detect AF & contrast AF difference. This link may help: i read from wiki too. got blur when they got into the technical thingy. http://en.wikipedia.org/wiki/Autofocus With contrast AF, the camera basically has to hunt and continuously compare contrast to get the best focus. That is why you will see the AF goes from blur to sharp, then become blur again, before finally become sharp and nailing the focus (this is when you hear the focus confirmation beep). This is most obvious in PnS cameras and handphone cameras. However, with phase detect AF, the AF module can know instantly if the subject is in front or behind the current focus point. It will also know HOW FAR away is the subject from the focus point. This gives the camera added information and enables it to quickly nail the focus. For moving subject, the AF module can even tell how fast the image is going out of phase, and in which direction (going back or going front) hence can predict the focus point. hmmm..so older SLRs like my dinosaur still uses contrast AF right? but for phase detect, usually people dun need to select their focus points anymore? unless they wanna do it manually?  OT: managed to borrow an EP1, going to play with it tonight  |
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Aug 25 2010, 05:27 PM
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Elite
3,928 posts Joined: Jan 2003 From: Incheon, Korea.. currently in Miri, Soviet Sarawak
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if u think u going to shoot video 51% of the time, get A33/55
if u think u going to shoot still photo 51% of the time, the A560/80 is better choice no matter what. |
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Aug 25 2010, 05:56 PM
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Senior Member
3,065 posts Joined: Jan 2003
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is 50% 50%
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Aug 25 2010, 06:01 PM
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Elite
3,928 posts Joined: Jan 2003 From: Incheon, Korea.. currently in Miri, Soviet Sarawak
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QUOTE(fansoption @ Aug 25 2010, 05:56 PM) is 50% 50% 50 50, buy both muahahaha |
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Aug 25 2010, 06:03 PM
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Senior Member
3,070 posts Joined: Dec 2006 From: Damansara
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QUOTE(kysham @ Aug 25 2010, 04:23 PM) Difficult to explain phase detect AF & contrast AF difference. This link may help: shortcut explanation :http://en.wikipedia.org/wiki/Autofocus With contrast AF, the camera basically has to hunt and continuously compare contrast to get the best focus. That is why you will see the AF goes from blur to sharp, then become blur again, before finally become sharp and nailing the focus (this is when you hear the focus confirmation beep). This is most obvious in PnS cameras and handphone cameras. However, with phase detect AF, the AF module can know instantly if the subject is in front or behind the current focus point. It will also know HOW FAR away is the subject from the focus point. This gives the camera added information and enables it to quickly nail the focus. For moving subject, the AF module can even tell how fast the image is going out of phase, and in which direction (going back or going front) hence can predict the focus point. contrast AF : zeet,zeet,zeet,zeet,zeet...!!!beep,beep...!!! (AF confirm) phase AF : zeet..!!!beep,beep...!!! (AF confirm) |
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Aug 25 2010, 06:08 PM
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All Stars
15,856 posts Joined: Nov 2007 From: Zion
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QUOTE(hazril @ Aug 25 2010, 06:03 PM) shortcut explanation : contrast AF : zeet,zeet,zeet,zeet,zeet...!!!beep,beep...!!! (AF confirm) phase AF : zeet..!!!beep,beep...!!! (AF confirm)  thanks |
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Aug 25 2010, 06:11 PM
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Senior Member
8,753 posts Joined: Jan 2003
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wah like that also can.. hahaha funny la..
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Aug 25 2010, 06:23 PM
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Senior Member
2,546 posts Joined: Jan 2009 From: Cyberjaya
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QUOTE(hazril @ Aug 25 2010, 06:03 PM) shortcut explanation : but in some lighting condition mine would go contrast AF : zeet,zeet,zeet,zeet,zeet...!!!beep,beep...!!! (AF confirm) phase AF : zeet..!!!beep,beep...!!! (AF confirm)  : (backlight)zeet,zeet,zeet,zeet,zeet,zeet, ZZZzzzzz  ---> change to MF ---> kacaakhoping in the a55 have improvement as it no longer use contrast base  This post has been edited by mastering89: Aug 25 2010, 06:25 PM |
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Aug 25 2010, 06:35 PM
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Senior Member
830 posts Joined: Dec 2009
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QUOTE(shootkk @ Aug 25 2010, 02:05 PM) The A33 and A55 cams have all the bells and whistles to attract the common consumers out there in the market. Things like HD video, sweep pano and etc. totally agree... tat's y have to resist the a55 1st. It's designed to be glitzy and show off-ish and great in attracting attention but it's not quite the professional device. It's not that I'm not excited about the innovation Sony is showing but I'm more interested in how Sony will implement these feature into a semi-pro and pro body. EVF is fine for the entry level class but I do not think an EVF can beat an OVF in terms of practicality. We're staring at a miniscule screen with an EVF. Can we determine focus as well as we can compared to using an OVF? Can it give us a level of detail that is acceptable for pro macro work? If we sweep the cam around the room can the EVF keep up with it and not show us a smeared blur when the cam is in motion? A translucent mirror can provide continuous phase detect AF for video but it decreases the amount of light that can reach the sensor when taking pictures. It also makes an OVF darker as it does not refect as much light. Is there a way to incorporate a flexing transluscent mirror in a practical way so that we can get the best of both? I am still waiting for the A7xx before I get all excited but you guys go ahead and celebrate. P.S. At this point I am more excited about the price of the 85mm f2.8 lens than anything.  |
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Aug 25 2010, 07:59 PM
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Elite
6,075 posts Joined: Jan 2006 From: 3.1553587,101.7135668
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QUOTE(zstan @ Aug 25 2010, 04:55 PM) i read from wiki too. got blur when they got into the technical thingy. none of our alpha cameras employ contrast AF, only found in other brands' dslr that have video mode. then again, they only use contrast AF when in video mode, not in normal image capturing. hmmm..so older SLRs like my dinosaur still uses contrast AF right? but for phase detect, usually people dun need to select their focus points anymore? unless they wanna do it manually? OT: managed to borrow an EP1, going to play with it tonight it is the technology in the AF module itself you see the difference in AF speed in your dinosaur compared to my petroleum. do take note that A700 is older than your unit. QUOTE(hazril @ Aug 25 2010, 06:03 PM) shortcut explanation : best explanation so far contrast AF : zeet,zeet,zeet,zeet,zeet...!!!beep,beep...!!! (AF confirm) phase AF : zeet..!!!beep,beep...!!! (AF confirm) QUOTE(mastering89 @ Aug 25 2010, 06:23 PM) but in some lighting condition mine would go me likes this one too... : (backlight)zeet,zeet,zeet,zeet,zeet,zeet, ZZZzzzzz ---> change to MF ---> kacaakhoping in the a55 have improvement as it no longer use contrast base you just need to know where to point the centre AF point when in backlighted condition. find of a high contrast edge. eg. the hairline vs the backlight... it will lock focus almost immediately. its only when there is flare that AF is harder to lock on... if that is the case, use your left hand like a lens hood to block out the light direction that is causing the flare, then lock focus, then u can take away your hand and fully press the shutter all other alphas are have been using phase detect AF all the while, apart from the NEX This post has been edited by lwliam: Aug 25 2010, 08:09 PM |
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Aug 25 2010, 08:02 PM
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Senior Member
2,816 posts Joined: Sep 2008
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QUOTE(porkchop @ Aug 25 2010, 02:56 PM) aaa a550 price already drop lo..so sayang i bought expensive thing drop til how much?? |
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Aug 25 2010, 08:14 PM
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Senior Member
1,982 posts Joined: Jul 2007
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Aug 25 2010, 08:17 PM
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Elite
6,075 posts Joined: Jan 2006 From: 3.1553587,101.7135668
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eh noprob, u were there as well?
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Aug 25 2010, 08:35 PM
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All Stars
15,856 posts Joined: Nov 2007 From: Zion
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dinosaurs vs petrol. dinosaur still older lehhh!!
paging for moo~ are u going for the miss kbu thingy tomorrow? |
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Aug 25 2010, 08:38 PM
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Senior Member
1,982 posts Joined: Jul 2007
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QUOTE(lwliam @ Aug 25 2010, 08:17 PM) eh noprob, u were there as well? Yuppp .. u ?And one more ...  Sony Alpha National Zoo Challenge by niznoprob, on Flickr |
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