[EOS1017]

請教各師兄：
本人想購買原廠長焦距作映景、打雀為主，有時映吓人像。所以我選擇300mm f/4及100-400mm f4.5-5.6，但兩鏡我知各有長短，300mm恆定光圈，有講成像好過100-400，但100-400機動性大過定焦，不過亦有人話100-400係第一代IS、直推易入塵及鏡齡己10年不適合數碼相機。我現用20D及有17-40 f/4,24-70 f2.8。請賜教，謝謝！

[pauljr]

買EF300mm F/4L IS USM啦...

Zoom...可以用腳...

[tyuen]

If you go mainly for birding, you will want a longer lens. And if you want image quality, a 400/5.6 is better than 300/4+1.4 (although this combo is really good). Moreover, the autofocus speed of 400/5.6 prime lens is faster than 300/4+1.4.

But if you use it for several purposes, get a 100-400/4-5.6. Yes, the IS is the oldest one. But does it matter? And don't bother the saying of dust.
However, it may be an issue that the autofocus speed of 100-400/4-5.6 is a bit slower than the prime lenses.

It is difficult to zoom with your feet from 100mm to 400mm and vice versa. And it is also difficult to zoom with your feet for portrait by using a 300mm lens. Moreover, the perspective is quite different to zoom with the feet.

[EOS1017]

好多謝兩位師兄高見，其實我當初傾向100-400因貪心有多焦距變化，加上萬成四眼康極力推薦。但check過好多資料加埋兩位意見後我知點倣，以後多多賜教。
THX!

[requicken]

師兄,你好,我都有用100-400 L is, 呢支鏡真係好sharp, 其實係買呢支鏡之前自己都諗左好耐, 買70-200 L 好定係買 100-400 L 好, 最後都係買大白好過,
因可以打雀,既可以影model,去到400mm 的最大 f5.6 光圈都以經有好朦朧的背景,加上又有 "is", 唔洗萬二蚊就買到, 個人覺得抵過 70-200 L is!
其實係D什麼game show, camera show, 書展, 漫畫展等等, 都見到有人係用70-200 L ,但係距離目標很遠,都係要用extender,那就冇左 f2.8 光圈, 計番條數都係一樣,但成像就絕對差過 100-400L !
仲有我唔知點解d人只會話直進式鏡易入塵,咁d旋轉式個鏡筒伸左出來個d鏡又冇人話會易入塵? 其實大家個鏡筒都係一樣伸出來姐, 只係一個推拉式變焦,一個旋轉式變焦, 我用左三年都唔見鏡組有一粒塵喎!
呢支鏡最大缺點係重,如果你適應左點用支鏡,會比到你無限的攝影樂趣!