[hotrock0038]

無知的人問 EF-S and EF lens and FF 機的問題。

首先是EF-S 其實為何不如實表明鏡頭的焦段在鏡頭上？ Example: 18-200mm ，其實是一定要 x1.6 用，即是=大約 28mm- 320mm，因它不可用在FF 機上，那支鏡頭其實永遠都不能用到 18-200mm 的焦段，為何不如實表明鏡頭上？

其次是用FF 機，在鏡頭選擇方面是不是比APS-C 機少呢？因FF 機不能用EF-S 鏡頭。

希望有 C-Hing 解答吓


Thank you!

[Obi-Wan]

18-200 is the actual focal length must be specified on the lens, 28-320 is the equivalent focal length, not the real one, so not necessary to specify on the lens

Also FF has more WIDE angle lenses to choose than APS-C

[GBAmon]

如果標上EFS 28mm- 320mm,那麼EF18-200mm用在APS-C 機上也會混亂呢!

[h0001244]

as Obi Ching said 18-200 is the actual focal length must be specified on the lens.....
28-320 is equivalent to film size 36x24mm angle of view, the physical focal length doen't change at all
you can say "why not specify the angle of view" , that makes sense.... angle of view depends on the sensor size......
then ef-s 17mm has same specified angle as ef 28


<<<其次是用FF 機，在鏡頭選擇方面是不是比APS-C 機少呢？因FF 機不能用EF-S 鏡頭 >>
you can say so, but for same focal length
FF vs APS
ultra wide vs wide
wide vs normal towide
normal vs little tele
tele vs more tele

[pongyee]

http://www.dcfever.com/forum/read.php?f=7&i=26009&t=26009&phorum_auth=b7a1e5abf3f6a4a93aecaf2fddcb0443

[hotrock0038]

I'm understand more than before and thank you all C-hing replied.