ricrick

then u can sell it to mucc1928 and get a 小小白 la

mucc1928

Thank you for all the reply here.

I am looking into this: EF F1.8
http://www.futureshop.ca/catalog ... ogon=&langid=EN

1) 1.8 is the apenture.  but where do you find the information for the depth?
2) Also, for this kind of len, it is hard to picture things far away, like scenary, right?

How about this one?  EF 55-200mm F/4.5-5
http://www.futureshop.ca/catalog ... ogon=&langid=EN
3) Does it mean it is F1.4?  So that's why it is more expensive?  
4) Regarding about the mm part, that is the focal length.  Is that the same as depth?

So there is no way 一鏡走天涯?

Catpiano

一鏡走天涯 is never good idea ..   

I only use zoom lens when ..  I have to ..

SiuBLoDau

22# mucc1928

If there is a lens that covers every need, then most camera manufacturer will close down for sure.  LOL

The focal length ( in mm ) is another indication of how much angle it covers.  See here

http://www.usa.canon.com/app/html/EFLenses101/focal_length.html

The aperture, in F, is the diameter of the 'hole' of aperture wide open when divided by the focal length ( e.g. 50mm f1.2 means the max hole is 50mm/1.2 = 41.67mm in diameter ).  The larger the shallower the depth of field.

Some more ideas on Depth-of-field:

http://en.wikipedia.org/wiki/Depth_of_field

It will be very helpful to understand what is meant shutter speed, aperture and focus length and how they affect your picture.  No matter what camera / system you use, those basics will last forever!!!

My 2 stupid cents.

Catpiano

thx for .. siu la lo dau !

SiuBLoDau

mucc1928.... to decipher a Canon lens:

EF 55-200mm F/4.5-5.6

EF = the mount.  All nowadays Canon lens are EF ( for full frame ) or EF-S ( for non-full frame ) lens.  Older manual focus are FD lens.

55-200mm = focal length = angle of view.
F4.5-5.6 means aperture at 55mm is f4.5, while 200mm is f5.6

Depth is a combination of focal length and aperture.  The longer the focal length ( e.g. 200mm ) and the larger the aperture ( i.e. a small number, say, f1.2 ) will give you the most shallow ( blurred ) result.  

I would say, to make things less complicated, the cheapest way to see what sharpness and shallow depth of field are -- 50mm f1.8.  Can't go wrong.  It is so light weight that you just get a lens pouch and throw it in your backpack -- you can still have your 18-55mm for landscape, and when you need a portrait lens just search your backpack lor.  That 55-200mm is not expensive -- just the 50mm f1.8 is too cheap.

Well.. this guy got a web page that compares many lenses and how they render the background:

http://www.kenrockwell.com/nikon/85mm-bokeh.htm

Oops... talk too much I think :S

阿九

靚嘅天涯鏡唔係無，只不過係買唔買得起，同係咪咁方便拎出街o者
EF 20-400mm f2.8 IO USM IS
http://www.canonrumors.com/wp-co ... /04/canoniolens.pdf

Catpiano

Ar 9 .. that one is the JOKE for april fool day ar ..   

Even the pricey 28-300 IS L    ( $3k ? )  isnt that good in QC, not even as good as $120 50mm F1.8 .....  and it is heavy ...  ( not much different then 24-70+70-200F4 )

Which is really pointless for MOST users ..  

however, some case, when you cannot change lens .. ( ie shooting wild life, or go desert .. not allow you to change lens or carry 2-3 bodies .. )   It was also design for FILM ...  nowaday, with APS camera, those 18--200, or 18-250 .. is 1/4 the weight, 1/8 the price .. and 95% the quality .. ( easy to make APS lens, no worry for edge performance, as small lens, one reason why 4/3 lens are so damn good )

^_^

mucc1928

Thank you for the kind explanations here! Catpiano and SiuBLoDau!  i would need sometimnes to digust the information here.

I want to make the right choice....the reason is...i am not going to keep this beginner camera long.   when i upgrade, I would go for a higher budget or different brand.  Therefore, i don't want to invest too much on this body.   Well, seems like $200-300 is a must for brand new....and around $150-200 for used.

once again, thank you!

Catpiano

If u like Bokeh ..  APS size camera ( D300, D90, 50D, 450D, A350 etc )   then it is not that easy ..  ( one main weak area for APS camera .. )

Search for some sample image from 70-210 F4 la.. ( both Nikon and Canon version are good )

I just sold my 70-210 Canon one .. and I dont think I have digital example ... may be just few .. and I dont know where my wife back them up ..

Since you can still aim at 210mm, and @ F4 .. good and smooth bokeh.  again, it is not as handy as 55-250 etc ..  but great GLASS !