[evoevo]

各位c兄; 新丁有一支18-200的kit鏡,但縮至最短時(18mm)
但它的長度約有5-6吋,
另看到一支50mm的鏡的長度約得3-4吋.

理論上50mm應該長過18mm. ?
請各位指教一下?

另外支18-200的kit鏡,,縮至最短時覺得唔夠wise想買多一支,
應該買幾多mm呢?無指定影乜,風景、人像、貓狗、花,見乜影乜?

[girlkiller]

You need wide Lens
EFS 10-22 or TOKINA 12-24

[ACanonGuy]

Do you think 18mm 的長度約有5-6吋 is because it is a zoom lens and the design needs to account for the 200mm end? I think the physical 長度 has something to do with 焦距 but there are also other internal elements that make up the physical length.

As for if you want something wider than what you have, 18-200mm gives you an diagonal Angle of view (APS-C) 74º - 8º meaning 74º at the 18mm end. This chart gives you the angle of view for other Canon lenses. For example, the EF-S 10-22mm will give you an angle of view of 107°30' on the 10mm end which is very wide on a APS-C sensor. Of course there are other options other than Canon but I don't have experience with them. Hope this helps.

http://www.usa.canon.com/app/pdf/lens/Lens_Extender_chart_new.pdf

[h0001244]

Lens construction is a difficult topic (at least to me)

Over 80% zoom lens I used before
Wider angle -> shorter body length
Tele angle -> longer body length

But there are exceptions like 24-70L
Wide angle -> longest
tele angle -> shortest

Few lens
Wide angle -> shorter
mid range -> shortest
tele angle -> longest

In your case, prime 50mm would be shorter than zoom lens due to prime is more simple constructed.

[evoevo]

唔該晒