[andy413hk]

請問各位師兄,例如 50mm or 55mm-250mm
那兩個mm 是什麼 數值 ???

[wesleyyau]

鏡得一個數值就係定焦鏡o既焦距...
鏡有兩個數值o既就分別係最廣角焦距同最遠攝焦距...

[jazyee]

"focal length" check it yourself please!

[andy413hk]

我支鏡係 55mm-250mm
咁可以幾遠

另外想問sigma 70mm-300mm &
canon 55-250mm

邊支成像好d

[jazyee]

http://www.tamroneurope.com/flc.htm

[onjo3]

different mm on different format DSLR, will have different sight angle,
it s very professional topic,
ASPC standard is 30mm
FF is 50mm
olmypus is 25mm...
coz their Sensor are different size.
300mm on 50D or 500D, =480mm
enough for shoot the moon very clearly
55-250 is good, highly recommend
for avoid a blur picture:
u need use at least 1/50 sec shutter on 250mm, turn on the IS
sigma one u have to use at least 1/400 sec on 300mm, (no IS version)

[andy413hk]

thx