efs17-55 color tone and corner area resolution is better a lot,except this,IS is also a important feature except you always carry a tripod with you.
for tele lens,you must get a IS lens if you shoot at tele ends.somtimes you just need to keep shutter at 1/125s-1/160s with IS on at tele end can get ok sharp photo with your kids slow moving at outdoor.you can consider 70-200f4is or 70-300is or 55-250is~~~
flash is very important if your kids over 1 years old,don' use flash if your kids just 0-1 years old
lens street price could refer to dchome.net canon forum
usm是否對焦快很多?for ring usm,yes
is在此焦段是否需要?more important at tele end
副廠是否可靠?it depends,some of them are good like sigma 150mm macro.but i would not prefer a16.....you never get sharp at corner area......
己有光圈2.8,是否不需再買定焦50/1.8(雖然很便宜)?it depends and i prefer to buy ef35f2 for indoor use.can close focus at 0.25m
1. 上述鏡頭仍欠55-70一段,其實可否 “人肉變焦” 搭夠? 即系用標準變焦鏡頭時行近主體少少,用遠攝變焦鏡頭時行遠主體少少。
normally people use 35-135mm range for portriat shoot~~~i would highly recommend 24-105is use on 40d for general family photo as the relative focal length become 3x-16xmm range which is the most useful focal length to suite your need.But if you have other usage rather than just take photo with your kids,17-55is would be much better
Big aperture can give you nice DOF background and 85mm/135mm focal length lens can give you much more beautiful DOF at big aperture compare to all 50mm lens
2. 延伸管的作用是什麼? 可否在需要時加在小小白上以縮短焦距
填補55-70一段? 在相片質素、光圈級數或其他方面有否影響?
是否實際?
for 1.4x/2x tele converter,the design purpose is for take photo with very far object which you cannot shoot would a super tele lens like 300mm/400mm/600mm lens.PQ would be decrease and AF speed would be slow.So,normally would not use it for portrait shoot~~~
3. 除了保護鏡頭,遮光罩有什麼作用? 是否需要?
you must get a hood for your lens,mostly the hood would help you to avoid un-wanted light source get in the lens.e.g.you may find it helpful when you take photo at night with a lot of street light which may affect your photo quality
4. 還有什麼裝備需要購置? 例如濾光鏡?
i don't use UV filter except go to the beach....
if big aperture is your need,i would go for prime lens instead of zoom as aperture f2.8 is not big enough for nice DOF background.why don't consider 85f1.8,135f2?