不懂就问哈 各位能人大侠 --- 莱卡相机请教

向问天

日月神教光明左使
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见图

1. 为什么有上下两排光圈数?
2. 中间那排距离到底怎么用?

 

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第一排数字是调节光圈的大小。第二排数字是对焦用的。第三排数字是景深表。

也难怪向老大不知道,用惯自动对焦镜头是不看景深表的。

在没有自动对焦的时代,我们是用景深表和超焦距来抓拍的。

比如上图,如果你把光圈调到16,把对焦的无穷大对准第三排右边那个16指的地方,左边的16大概会指到3m的地方,这也就是表示景深从3m到无限远,这样不用调焦,3米以外都是清楚的。

从景深表你可以看到F2以下基本没有景深。
 
第一排数字是调节光圈的大小。第二排数字是对焦用的。第三排数字是景深表。

也难怪向老大不知道,用惯自动对焦镜头是不看景深表的。

在没有自动对焦的时代,我们是用景深表和超焦距来抓拍的。

比如上图,如果你把光圈调到16,把对焦的无穷大对准第三排右边那个16指的地方,左边的16大概会指到3m的地方,这也就是表示景深从3m到无限远,这样不用调焦,3米以外都是清楚的。

从景深表你可以看到F2以下基本没有景深。



懂了。
谢谢!
下次万一碰到莱卡,咱也会用:cool::D
 
老托,奇怪了,这个canon镜头怎么只有半个景深表?

中间窗口白杠右边是红字从左到右是50,35,24.

 

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Focusing infrared

Most manual focus 35 mm SLR and medium format SLR lenses have a red dot, line or diamond, often with a red "R" called the infrared index mark, that can be used to achieve proper infrared focus; many autofocus lenses no longer have this mark. When a single-lens reflex (SLR) camera is fitted with a filter that is opaque to visible light, the reflex system becomes useless for both framing and focusing, one must compose the picture without the filter and then attach the filter. This requires the use of a tripod to prevent the composition from changing. A sharp infrared photograph can be done with a tripod, a narrow aperture (like f/8)[citation needed] and a slow shutter speed without focus compensation, however wider apertures like f/2.0 can produce sharp photos only if the lens is meticulously refocused to the infrared index mark, and only if this index mark is the correct one for the filter and film in use. However, it should be noted that diffraction effects inside a camera are greater at infrared wavelengths so that stopping down the lens too far may actually reduce sharpness.

Most apochromatic ('APO') lenses do not have an Infrared index mark and do not need to be refocused for the infrared spectrum because they are already optically corrected into the near-infrared spectrum. Catadioptric lenses do not require this adjustment because mirrors do not suffer from chromatic aberration.

Zoom lenses may scatter more light through their more complicated optical systems than prime lenses, that is, lenses of fixed focal length; for example, an infrared photo taken with a 50 mm prime lens may look more contrasty than the same image taken at 50 mm with a 28–80 zoom.

Some lens manufacturers such as Leica never put IR index marks on their lenses. The reason for this is because any index mark is only valid for one particular IR filter and film combination, and may lead to user error. Even when using lenses with index marks, focus testing is advisable as there may be a large difference between the index mark and the subject plane.

http://en.wikipedia.org/wiki/Infrared_photography
 
那个不是景深表,我感觉应该是IR摄影用的。

不是每个镜头都有的,有是说明这个镜头是IR compatible.

http://www.lensplay.com/lenses/lens_infra_red_IR.html
错的

第一排是光圈大小
第二三排是对焦的距离
最下头的是zone focus/scale focus的指示
看图示
hyperfocal.jpg
如果你用f16对焦到0.9米左右位置,那么0.7米和1.5米以内的东西都算"acceptable focus",就是可以接受的合焦。
如果你用f1.4对焦到0.9米左右位置,那么只有0.9米的物品算"acceptable focus"。
这个是为了rangerfinder和手动头快速抓拍时候用的一个辅助的东西,手动光学取景器合焦没黄斑或者裂屏一类的话,合焦很累,这个算是简化难度了。
在现代电子对焦镜头的时代可有可无。
 
错的

第一排是光圈大小
第二三排是对焦的距离
最下头的是zone focus/scale focus的指示
看图示
浏览附件319893
如果你用f16对焦到0.9米左右位置,那么0.7米和1.5米以内的东西都算"acceptable focus",就是可以接受的合焦。
如果你用f1.4对焦到0.9米左右位置,那么只有0.9米的物品算"acceptable focus"。
这个是为了rangerfinder和手动头快速抓拍时候用的一个辅助的东西,手动光学取景器合焦没黄斑或者裂屏一类的话,合焦很累,这个算是简化难度了。
在现代电子对焦镜头的时代可有可无。


你的这个说明跟老托在第二楼说的是一个意思。
谢谢!
 
还好向老大作证,不然兄弟二十多年的功力白费了,呵呵。
 
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