[c8133594]

In theory, auto focus can be achieved by shifting CCD at DC, just wonder why there is no company doing that? Look like this more faster than rotating lens and also reduce the production cost of AF lens

[pauljr]

睇嚟好有道理...

不過...要塊感光原件响機身裡頭移前移後嚟對焦...部機個Size...

再加上連接感光原件嘅其他零件都需要移動...

再加上...要安裝可以令以上零件移動嘅零件...

再加上活動部件都需要能源推動...同時機械活動時所產生可影響感光原件嘅熱力...

其實...閣下咁聰明都諗到...無理由班相機廠造咗成幾廿年相機都會諗唔到卦？

點解依然仲係用鏡頭移動作對焦？...當然有原因啦...

查實...以機背移動作自動對焦...係有出產過...

[pingu_hk]

good question!

But

1. what is the amount of distance travelled (displacement) in the DC/DSLR? For small size CCD/CMOS, the distance may be just a 0.1mm for moving from min. focus distance to infinity. That requires higher precision mechanism to control the movement.
2. there are a no. of wires attracted to the CCD/CMOS, although it can be designed to allow translational movement as in pentax, sony, KM's technology) BUT NOT movement along the optical axis. Excessive movement may weaken these wires

[correct me if I am wrong]

[Canasony]

contax 在遠古時代係唔係造左一部移動 film plane 既 AF 菲林機?

[vaworld]

講得唔好聽呢個係時光倒concept.
唔講 contax AX曾經用過呢種方式自動對焦.
舊式或者大format相機用菲林平面移動或bellow對焦多的是.
並不是甚麼新concept.

再者不單機身菲林平面對焦會limit對焦距離.
再加上咁樣做就失去floating element或者 internal focus.
呢類技術的優點.
另外Zoom一類鏡頭就更加有問題.

[Canasony]

冇錯丫, 計落一d優點都冇

[c8133594]

>再加上咁樣做就失去floating element或者 internal focus. 呢類技術的優點.

Just wondering what is the advantage?