55mm 300mm what do they "really mean"

lynnmalynnma Moddess EmeritusPosts: 5,158Super Moderators moderator
edited January 21, 2004 in Technique
Hi all,

I'm the newbie with the Bull picture and my husband asked me what does 55mm and say 300mm really refer to? he can't figure it out, so after fumbling around for ten minutes I realized I have'nt a clue. What is that actually measureing??
Also on the subject of RAW.. I'm just starting out with my new Rebel 300D and I'm taking everything on RAW.. as a beginner do I really need to do that? or at my level would I be just as well staying with fine.

By the way, I love this site.. lots to learn and great photographs to see. Thanks.
Lynn

Comments

  • cletuscletus Master of Craposition Posts: 1,911Registered Users Major grins
    edited January 21, 2004
    Hey Lynn,

    First 55mm and 300mm describe the focal length of the lens. Focal length is an optics term. I can't come up with a good technical explanation so... Basically the longer the focal length, the more magnification and narrower the field of view. So a 55mm lens wont have the magnification that the 300mm lens does but it has a much wider field of view.

    To find the difference in magnification between two lenses you can divide the two focal lengths. For example comparing a 300mm and a 55mm lens you would divide 300 by 55 which is just about 6. So with the 300mm lens things would seem about 6 times larger than they would with the 55mm lens.

    Also a zoom lens in simply a lens where the focal length can vary (from 70mm to 300mm for example).

    The RAW vs. Fine issue is really up to you. If you're going to be doing a lot of work with your images on the computer, RAW files are more flexible. Otherwise, there probably isn't a whole lot to be gained by shooting RAW files. However, keep in mind that even if you're not doing a lot of Photoshop work now, you might want to in the future. A couple years from now you don't want to be going back through your older images and saying "I wish I had this as a RAW file!"

    Keep up the good work!

    -Eric
    The digital grin photography forum's only slack-jawed moderator.
    ab0wa.smugmug.com
  • cmr164cmr164 Focus! I need Focus! Posts: 1,542Registered Users Major grins
    edited January 21, 2004
    lynnma wrote:
    Hi all,

    I'm the newbie with the Bull picture and my husband asked me what does 55mm and say 300mm really refer to? he can't figure it out, so after fumbling around for ten minutes I realized I have'nt a clue. What is that actually measureing??
    Those are the distances from the optical center of the lens to the imager when the lens is in focus. The shorter distances give a wider field of view and a longer distances give a greater magnification.
    lynnma wrote:
    Also on the subject of RAW.. I'm just starting out with my new Rebel 300D and I'm taking everything on RAW.. as a beginner do I really need to do that? or at my level would I be just as well staying with fine.

    By the way, I love this site.. lots to learn and great photographs to see. Thanks.
    Lynn
    The things you can do with RAW images with white balance and editing are really impressive. Even if you do not use or even understand them now, you will one day and then you will want the images you took before to be RAW. So keep on using raw mode. From the first day that I had a camera that could save raw image data that is all I have done.

    Charles

    PS Looking at the Bull and the Horse, your instincts are good. Shoot as much as possible. Experiment as much as possible.
    Charles Richmond IT & Security Consultant
    Operating System Design, Drivers, Software
    Villa Del Rio II, Talamban, Pit-os, Cebu, Ph
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