Lenses

[Bendixen]

Can someone give me e quick intro to lenses? How can I tell if a lens is good or bad?

- what does AF mean ?
- what does e.g. f/2.8 mean?
- Can I be sure all lenses fit my camera?

I can tell that there's a big price difference between what to me looks to be similar lenses.

[ssim]

Welcome to the forum. There are lots of resources available on the net to answer your questions.

You could try http://photonotes.org/ . It has a dictionary that is fairly good for answer questions such as "AF" which is AutoFocus.

You didn't mention which camera you have. Another reasonable solution would be to go to your manufacturers website. In Canon's case they give you a good overview of each lens.

[Bendixen]

Well, at this time I do not have a digital EOS camera, but I'm thinking about buying a D10 or D300. I want to know more about the lenses because I want to buy a camara that gives me maximum freedom to choose as many lenses as possible.

Currently the only camera I have is a Canon A70

[bnpndxtr]

Bendixen wrote:but I'm thinking about buying a D10 or D300.

That "10D", not D10. Easy mistake to make.

Bendix Enigneer perhaps?

[psk4363]

Here's a "quick intro" as you asked for: -

1) 'AF' means simply 'autofocus' . Hence a Canon AF lens is one that will work on Canon autofocus cameras which have the EOS AF fitting, such as the 10D and the D300;

2)The f/2.8 is merely a numerical figure given to denote a ration concerning the 'maximum aperture' of the lens. The 'aperture' in simple terms is how wide the internal diaphragm inside the lens will open to allow light through to the CCD or CMOS (the chip or film in traditional cameras). The smaller the number the more light a particular lens will allow to be passed; the smaller the number the 'faster' the lens is;

3) If the maunufacturer of the lens states that their particular lens is Canon AF compatible then you will have no problems whatsoever. Virtually all of the main independent lens manufacturers (Sigma, Tamron, Tokina, Cosina, etc.) have a range of lenses suitable for Canon EOS cameras.

Hope this helps,
Barry

[psk4363]

Oops , in para 2 above that should read "denote a ratio" - fingers too quick for aged mind!

Barry

[Jesper]

Here is an explanation of what f/... means: A Tedious Explanation of the f/stop: http://www.uscoles.com/fstop.htm

[Canuck]

Hi!
Welcome to the forum.

In regards to you're post about the price, that can be explained really easy! What makes a lens expensive is the material in the barrel so to speak. The cheaper lenses use glass that compared to say Canon L glass is great for light dispersion (like the prism). Note that a high diffraction lens will make for non so hot pics. It makes them dull/fuzzy. Canon L glass using LD/ULD/Flourite (Ultra (Low Dispersion) elements) makes for a much cleaner and tighter rainbow and makes a real bad prism. This also makes for sharper pics and more vibrant colours. As far as lenses go, you get what you pay for. I have seen how crappy cheap lenses can give you for photos and I've seen higher end lenses that, when armed with the knowledge to use them to their full capacity will result in pics that will blow you away. CDS has taken some bird shots that are unreal, as have I with the moon and Concorde. I'm not about to release Concorde pics. The Concorde pic are for me. Have a look at: http://www.photography-on-the.net/forum/viewtopic.php?t=17977!!! I have since been bitten by the Canon L bug, and like many others around here can't get rid of it.

Cheers from England,
Canuck