New to DSLR, Need Some Advices.

Discussion in 'Digital Photography' started by xkRoWx, Jul 8, 2008.

  1. xkRoWx macrumors regular


    Oct 15, 2007
    Hi, I have recently bought a Nikon D40 DSLR camera, and instead of the standard 18-55mm lens it was equipped with a 18-70mm lens. I would like to know your opinion for this lens.

    I have some technical questions, since the last time I did SLR photography was about 3 years ago in a high school program (only messed around with the 35mm cameras in ART class). I don't like reading tutorials and manuals and often find them very long and confusing (I understand things better if they were "summarized" or explained using everyday English), hopefully these questions won't be a pain in the ass to be answered and all help is very much appreciated.

    1) What is the difference between ISO and exposure? How is shutter speed affected? I noticed that sometimes the shutter speed is 1/60 and sometimes is 1s using the same ISO. How do I manually control the shutter speed?

    2) Aperture? Focal length? White balance?

    3) What does 18-70mm means? 1:3.5-4.5? What does these values mean on a lens?

    Sorry in advance if the answer end up being a 10 paragraph long tutorial. :/
  2. marioman38 macrumors 6502a


    Aug 8, 2006
    Elk Grove, CA
  3. Hmac macrumors 68020

    May 30, 2007
    Midwest USA
    I would highly recommend Thom Hogan's e-book of the D40. It nicely summarizes the camera and offers practical operational tips in plain english.

    However, the questions you're asking aren't about camera function, they're about basic photography. The answers are built on the very fundamentals of photography, and explaining them (the subject of innumerable books, websites, and courses) in an online forum just isn't going to be possible.

    Having said that:

    ISO, shutter speed, and aperture are all interrelated means of getting the correct amount of light onto the film/sensor so that you end up with an image that is correctly exposed (provides a dynamic range somewhere within the 11-or-so stops that the human eye can discern). For a given sensor sensitivity (ISO), you can control that amount of light by either using a longer shutter speed with a smaller aperture, or a larger aperture with a shorter shutter speed. If a given aperture/shutter-speed combination doesn't give you the exposure you want (image too dark), you can increase the ISO to make the sensor more sensitive to light ( however,this will usually increase noise in the image - you usually would want to use the very lowest ISO you can get that will still allow you to get a correctly exposed photograph). You control the ISO on a D40 by pushing the ISO button and turning the rear thumb wheel. You control the aperture in aperture-preferred mode with the front control wheel. If you're in shutter-preferred mode, that front wheel controls the shutter speed. The purpose of controlling shutter speed vs aperture relates to controlling (freezing or not) subject motion vs controlling depth of field (blurred foreground/background).

    White balance is a means of making sure that whites in your image are truly white. If they're not, the color tinge will permeate the whole image.

    A lens has a length wherein the image it's seeing can be focused on the sensor. On an 18-70 mm lens, that focal length can be adjusted between 18 mm and 70 mm. At 70 mm, the image will be larger (magnified) and at 18 mm it will be smaller (zoomed out).

    F-stop is the ratio of the lens focal length to the diameter of the shutter. The lower the f-number, the more open is the aperture, and the more light is let in to the film. The label "1:3.5-4.5 means that the largest aperture the lens can manage is f/3.5. As you zoom in on a subject (shorter focal length), that maximum aperture becomes smaller - f/4.5 (this is due to the design of that particular zoom lens - some more expensive lenses will be capable of keeping their max aperture throughout their zoom range). And some more expensive lenses will have lower f-numbers (larger maximum apertures).

    There you go..all of photography in just a few paragraphs. Happy shooting!

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