Re: [閒聊] SONY CZ24-70/4 eprice測試
真是慚愧，重新翻了一下"Depth of field and Bokeh"
才發現在第三十二頁的左側有這麼一段文字
"If you look at this picture very closely, you can see another interesting
effect – all the defocused spot images contain a circular structure. It is
possible to recognise from this that the lens has an aspherical surface as
these surfaces are often not as smooth as a conventionally polished lens.
Particularly in the case of lenses which are manufactured by pressing hot
liquid glass it is possible to recognise the traces of the turning process
with which the mould was manufactured.
It is possible to combine rotational and pivotal movements when polishing
spherical surfaces because the curvature of the surface is the same
everywhere; in this case no traces are left. In the case of aspherical
surfaces the curvature is variable and therefore demands other processing
techniques. Residual unevenness of these surfaces becomes visible if a very
small light source is reproduced very much out of focus."
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 106.1.131.62
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02/05 23:41, , 1F
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我的解讀是研削仍可能會有(因為非球面的不規則性)，只是沒有模鑄那麼明顯
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※ 編輯: atropos 來自: 106.1.131.62 (02/06 00:03)
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