决定自动聚焦速度的因素

来源: Big_Benz 于 2009-07-27 10:58:28 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (831 bytes)

I understand large aperture lenses allow higher shutter speed - people call them fast lenses. On the other hand, I am not sure I understand when a lens is said to AF slow, independent of camera body.


Under the low light situation, some slow lens does not have enough light to the sensor so the system "hunts", taking time to lock on the object. That is a combination of camera body and the lens aperture.

With bright sun shine and a good contrast object, will one lens AF slower than others on teh same camera body?

I have a Sigma 18-50mm F2.8. When I first used it on a D300, I was amazed by the AF speed comparing the same lens on a D80. I had to let it focus on my hand to see if AF is working. So, I may be wrong, but I think the aperture and the body are two biggest factors for AF speed.

所有跟帖： 

• 有的镜头由机身驱动，有的镜头自带对焦马达， -sjmj- ♂ 给 sjmj 发送悄悄话 sjmj 的博客首页 (100 bytes) () 07/27/2009 postreply 11:09:01

• thank you, now I know why my 150mm Macro -Big_Benz- ♂ 给 Big_Benz 发送悄悄话 Big_Benz 的博客首页 (82 bytes) () 07/27/2009 postreply 11:45:57

• For AF-I micro lensscrew is much slower than mormal -WayCool- ♂ 给 WayCool 发送悄悄话 WayCool 的博客首页 (107 bytes) () 07/27/2009 postreply 16:08:43

• 镜头聚焦时都是开放最大光圈。最大光圈不同的确影响弱光下的聚焦性能 -U96- ♂ 给 U96 发送悄悄话 U96 的博客首页 (335 bytes) () 07/27/2009 postreply 11:16:36

• so 镜身聚焦马达 is not always >> 机身聚焦马达?? -Big_Benz- ♂ 给 Big_Benz 发送悄悄话 Big_Benz 的博客首页 (195 bytes) () 07/27/2009 postreply 11:42:13

• D？机身的聚焦马达电压高，功率大。但驱动长焦头的速度还是不足。 -U96- ♂ 给 U96 发送悄悄话 U96 的博客首页 (70 bytes) () 07/27/2009 postreply 11:46:19

• w/same apterture/focal lenth, Af-S lens much fast than non AF-S -waycool- ♂ 给 waycool 发送悄悄话 waycool 的博客首页 (96 bytes) () 07/27/2009 postreply 11:20:17

• Same long focal length - pick aperture or AF-S? -Big_Benz- ♂ 给 Big_Benz 发送悄悄话 Big_Benz 的博客首页 (349 bytes) () 07/27/2009 postreply 11:37:54

• AFS！尼康从90年代的衰落就在于佳能的USM兴起。 -U96- ♂ 给 U96 发送悄悄话 U96 的博客首页 (0 bytes) () 07/27/2009 postreply 11:40:03

• I think you should have batter answer. -WayCool- ♂ 给 WayCool 发送悄悄话 WayCool 的博客首页 (233 bytes) () 07/27/2009 postreply 12:20:10

• I can't tell the AF difference -Big_Benz- ♂ 给 Big_Benz 发送悄悄话 Big_Benz 的博客首页 (416 bytes) () 07/27/2009 postreply 12:40:40

• 善意地建议一下，批评意见会受到欢迎的，但是建议尽量避免 -sjmj- ♂ 给 sjmj 发送悄悄话 sjmj 的博客首页 (133 bytes) () 07/27/2009 postreply 14:57:28

• Thanks, so the AF-S design is a big factor too -Big_Benz- ♂ 给 Big_Benz 发送悄悄话 Big_Benz 的博客首页 (191 bytes) () 07/27/2009 postreply 12:43:35

• I add something may make it simple. -WayCool- ♂ 给 WayCool 发送悄悄话 WayCool 的博客首页 (285 bytes) () 07/27/2009 postreply 12:58:02

• 三月三knows... -BigV8- ♂ 给 BigV8 发送悄悄话 (0 bytes) () 07/27/2009 postreply 13:18:52

• 很多人誤以為是光線來決定AF的速度， -ct2009- ♂ 给 ct2009 发送悄悄话 ct2009 的博客首页 (235 bytes) () 07/27/2009 postreply 14:05:21

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