I have the nikon kit lenses: 18-55 and 55-200 which have two F numbers of F4 and F5.6.
What exactly does this mean? And at what point does it change from f to 5.6?
#1. "RE: Newbie question" | In response to Reply # 0PSAGuy Nikonian since 04th Nov 2008Fri 05-Apr-13 01:26 PM | edited Fri 05-Apr-13 01:27 PM by PSAGuy
Kelli....The f numbers refer to aperture (essentially how wide open the lens is....allowing light to pass through). f4 is more wide open and lets more light in than f5.6. Your lenses are "variable aperture", meaning they change the amount of light they let in as you zoom. The further in you zoom...the less light you let in, and as such, the more light needs to be available in your scene. Some lenses don't change...but they tend to be more expensive than a "kit" lens.
Aperture plays a role in allowing you to shoot without flash in low light and also in depth of field (i.e....what is in focus and what is not). Your camera's manual may explain this well...take a loook at it.
Enjoy your gear.
#2. "RE: Newbie question" | In response to Reply # 1KellyZ Registered since 01st Mar 2013Fri 05-Apr-13 01:51 PM
Thanks. I actually under stand the notion of lower fnumbers letting in more light than high.
What I was wondering about was how a lens had only the two. Now, as I understand your explanation, the minimum just varies with the zoom, and can't be fixed regardless of the zoom.
Knowing that, I have a frame of reference to study how it works.
#3. "RE: Newbie question" | In response to Reply # 2nwcs Registered since 15th Jan 2006Fri 05-Apr-13 02:14 PM
A good place to start your exploration is the Nikonians wiki:
And if you search for the term variable aperture zoom you'll find many good articles.
#4. "RE: Newbie question" | In response to Reply # 0
I too am a newbie.
To add to what has already been posted,your question puzzled me too until I found the answer that turned the light on for me in Darrell Young’s book “Mastering the Nikon d7000”. The F4 and F5.6 refer to the maximum aperture your lens can achieve at each end of the lens focal length. Using your 55-200 as an example, at 55mm the maximum aperture setting is F4 and at 200mm the maximum setting is F5.6.
Hope this helps
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