DSLR Guide: Know about Lens part:5
How to Tell the Maximum Aperture of a Lens
example:
* 50mm f/1.8
* 18-55mm f/3.5-5.6
* 28-300mm f/3.5-6.3
The first set of numbers represent the focal length or focal length range.
The second set of numbers these indicate the maximum aperture of the lens.there’s really no point in marking the MINIMUM aperture on the lens, because that’s pretty much the same for all lenses.
Constant Maximum Aperture.
The maximum aperture of a prime lens is only one.
With some zoom lenses, there can be TWO maximum apertures.because your zoom lens has a variable maximum aperture.
Example: 18-55mm f/3.5-5.6 zoom.
* At 18mm the maximum aperture is f/3.5
* At 55mm the maximum aperture narrows to f/5.6
Somewhere in the middle of the zoom range (30mm) you’ll get a maximum aperture number somewhere in the middle – say, f/4.
Zoom lenses like this are a real problem for professional photographers who control their cameras manually. This is because with a variable max aperture zoom, exposure settings constantly change as you zoom in and out.
But there are plenty of zoom lenses with constant maximum apertures.
Example: 28-70mm f/2.8 (2.8 is the max aperture at both 28mm and 70mm and everywhere in between)
What Max Aperture Do You Need?
| Lighting | Rationale | Max Aperture |
|---|---|---|
| Indoors | If you want to take photos indoors without a flash, you need to get a lens with a very wide maximum aperture to let in plenty of light | f/1.4 - f/2.8 |
| Overcast | Overcast days are especially challenging for sports photographers, who need to use fast shutter speeds to freeze motion | f/2.8 - f/3.5 |
| Shade | Shade is not as dim as a cloudy day and you have a bit more leeway when it comes to the maximum aperture | f/3.5 - f/5.6 |
| Daylight | In broad daylight it really doesn't matter what the max aperture of the lens is - you probably won't be using it because it lets in too much light and over-exposes the image | Any |
If your photos succeed or fail based on having a fast shutter speed (so that they don’t all turn out blurry) then you’re going to want to find a lens with a nice wide max aperture to help you get blazing-fast shutter speeds regardless of the amount of natural light.
Continue…next part.
http://rebeldigitalslr.com for more info
Popularity: 4% [?]
Related Article
Tagged with: 4.-DSLR lens • canon rebel • Dslr • nikon d • Review
Filed under: 1.-Common topic • 8.-Tips
Like this post? Subscribe to my RSS feed and get loads more!
Leave a Reply