I just purchased a D5100, my first DSLR. I've decided to try to learn to use the camera manually, as I did many years ago with an Olympus OM1.
I've set the camera for manual operation but there are some things that confuse me. First, the kit lens has an aperature range of 3.5 to 5.6. Given this, why does the camera allow me to select much higher numbers using the command wheel?
Second, and this will demonstrate my ignorance, what do the numbers 18 to 55 represent, Is there a relationship between these numbers and the aperature values?
#1. "RE: Lens/Aperature Confusion" In response to Reply # 0
If you have the kit lens it is a variable aperture lens meaning its max aperture at 18mm is f3.5 and at 55mm it is f5.6 so that means the lens at 18mm is max f3.5 to min f22 and at 55mm it is max f5.6 to min f22. Being that its max aperture is variable its max aperture at lets say 35mm maybe f4.5 to f22. Nikon and most stores list the max apertures for the shortest and longest focal length but not the minimum aperture. Just a marketing tool I think.
Here's a link to Nikon USA's sire with its spec's listed.
#3. "RE: Lens/Aperature Confusion" In response to Reply # 0
Hatboro, Pa, US
The 18 - 55 is a zoom lens which has a focal length of 18mm at it's widest setting and 55mm at it's narrowest setting. In order to keep the cost of the lens lower, the designers allowed the physical constraints of the lens to allow more light to pass in the wide end than in the narrow or mild telephoto end. That is why the lens is rated from f3.5 to f5.6. This lens is much different from the old manual focus lenses you're familiar with in the past. It has a built in computer chip which communicates to the camera body. This is why the camera command wheel can tell the lens to adjust it's aperture. Every lens that Nikon makes has an aperture range up to f16, f22 or even f32. Lenses with macro capabilities will even go higher like f45 the closer you get to an object. It's just the laws of optics at work.
You have a great camera in the D5100 and a very sharp lens in your AFS 18-55mm.
#4. "RE: Lens/Aperature Confusion" In response to Reply # 0
Tallahassee, Florida, US
You got some good answers, but just to clarify,
>...the kit lens has an aperature >range of 3.5 to 5.6. Given this, why does the camera allow me >to select much higher numbers using the command wheel?
When the lens is zoomed to its widest (18mm), the maximum aperture is f3.5, but as it zooms out toward 55mm the maximum aperture becomes f5.6. Those numbers are the widest apertures you can get, and what you are seeing with the command wheel is that you can narrow the aperture with the command wheel when the camera is set to aperture priority.
>Second, and this will demonstrate my ignorance, what do the >numbers 18 to 55 represent, Is there a relationship between >these numbers and the aperature values?
Those numbers are the focal length of your zoom lens. 18 means when it is set there, the lens has a focal length of 18mm, so is a wide angle. 55 means the focal length is 55mm, so is a mild telephoto on your camera. You can see the effect by turning the zoom ring from 18 to 55 and watching the view go from wide to narrow.
Now, to your question, the lens is a variable aperture lens, so in aperture priority (A on the mode dial) set the lens to 18mm, and the aperture to f3.5. Then notice, as you zoom toward 55mm, that the aperture number will rise until it gets to f5.6, so there is a relationship between the aperture values (f3.5...f5.6) and the focal length (18...55). As the focal length gets longer, the maximum aperture goes up from f3.5 to f5.6.
But notice if you set your aperture to f8 and zoom the lens, the aperture remains constant at f8. Once you get the idea of what those numbers mean and what they do as you zoom, you can just play with the camera and lens and see how they work. I hope that helps!
#5. "RE: Lens/Aperature Confusion" In response to Reply # 4
Thanks so much guys. I really appreciate your help. This lens really is different. On my Olympus, I was able to adjust aperature on the lens. Everything seemed more manageable on that old manual camera. I may have bitten off more than I can chew with the D5100, but I'll keep playing with it and reading about it here on Nikonians.
I'm glad I joined this forum because you guys really know Nikon.
#6. "RE: Lens/Aperature Confusion" In response to Reply # 5
The rules of exposure are the same as they were in the film days. Once you get used to the control layout shooting in Manual exposure mode should be much easier than you think. It is like riding a bike. Good Luck and Enjoy your Nikons!
#8. "RE: Lens/Aperature Confusion" In response to Reply # 0
I see you got your answers.
Lenses, most of the modern ones I know of are like this with cameras. Controls are in the camera for the most part.
Be careful of your lenses, if you have others to not try manual focus unless you have read the manual on it. I know that seems silly, but I have a friend that can't seem to break herself of the habit of wanting to grab the lens to manually focus when I have it set to AF. You can eventually mess up a lens doing that. Some lenses have a switch on the side for switching but you have to remind yourself to use it. LOL