really newbie question

[ilkhan]

Im looking at getting a dSLR and have a really stupid question.
focal length != focus. With focus being keeping everything sharp and, well, in focus, what does that make focal length, and how is that different than zoom or field of view then?

also: macro to me means really close photo work. But it doesn't seem like thats how its being used on the lens reviews Im looking at. So whats the photographers meaning of it?

 

[Joves]

If Im reading you correctly you want to know what the f-ratio and, numbers mean. What the f-ratio in photography is how much the camera stops down the light. The lager numbers a long numbers and, darker. Your high f-ratio say f/22 gives you greater depth of field or, more of what you are shooting is in focus over the whole area. A lower or short number like f/3.5 will only keep the central object in focus eveythingelse will be blurred. F-number control the amount of light getting to the sensor or, film as a way of controlling how the pic comes out. That is the easiest explanation. Also when you are shooting landscapse or objects at ininity the f-ration strictly control the ligh but does not afeect the depth of field. It will though afftect near by object in the foreground. Hope this helps.

 

[ilkhan]

<3 push email and seeing reply emails instantly.

Yeah more reading I think got me the answer. Focal length IS field of view. Focus is ensuring that the image is sharp on the sensor. Zoom is related to field of view as you get the same detail with less area, thus zoom. Zoom on a lens means that the lens has an adjustable field of ziew (focal length).

 

[Joves]

<3 push email and seeing reply emails instantly.

Yeah more reading I think got me the answer. Focal length IS field of view. Focus is ensuring that the image is sharp on the sensor. Zoom is related to field of view as you get the same detail with less area, thus zoom. Zoom on a lens means that the lens has an adjustable field of ziew (focal length).

Focal length is depth of field or, how far back the image will be focused from the central object.

 

[ilkhan]

Focal length is depth of field or, how far back the image will be focused from the central object.

Maybe Im thinking of the wrong term then. On a lens you have xx mm. That is the focal length, no? So the kit lens on a dRebel is 18-55mm, that 18-55 is the focal lenth, right?

The depth of field IS how much is in focus at once.

focal length shouldn't be the same as depth of field.

 

[ilkhan]

so I went down to circuit city and played with the display XTi for a bit.

Not as big as I remembered (+)
Solid feeling (+)
Plenty of controls (+)

It was on a security tie so that got in the way of really holding it. They had the crappy kit lens on (OMG jerky focus ring bad). I dont have any CF cards or I would have brought one to use in it while playing, to judge write times and picture quality when I got home.

The way Im looking at going now is to skip the kit lens (horrible reviews and that focus ring made me scream) and instead get the 28-135mm canon lens. Its a good bit of money for me ($410) but it has a much wider range and seems to be much more useful. The only concern I have is the 28mm*1.6 crop factor isn't very wide. Bit beyond the 50mm normal spot, but not by much. Would have good reach though.

The other lens Im thinking of would be the kit plus the 100 f/2.8 macro. I like small stuff and it would give me good reach when combined with the kit for wide angle. Supposedly its a very nice lens, especially for the price.