handicap18
<font color=blue>Husband, father of 3, and Disney
- Joined
- Oct 18, 2005
- Messages
- 4,860
I'm embarassed to admit that I just yesterday realized that the aperature opening of the lens is actually limited by...the lens itself. Gee, what a novel concept.So, the lens that's currently on my camera is a Nikon 18-135mm 1:3.5-5.6G ED. So does this mean that at 18mm, the aperature is at 3.5, at 135 it's at 5.6 and in between those focal lengths it's somewhere between 3.5 and 5.6??? If this is all true, then can someone explain to me what happened yesterday when I was playing around with both shutter and aperature priority and definitely had the aperature setting on the camera above and below the values on the lens? Does it max out at 5.6? What about when I had it at f9 or f11? I'm so confused.
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Along those lines, if one purchases a prime lens (like the 50mm 1.8d that I'm hoping to buy soon), how does that work when the camera tries to set an aperature in shutter priority mode. Will it ALWAYS be 1.8? Can the aperature opening be smaller if you want, but not larger than the value listed on the lens (like if it were 3.5, you could do 5.6 but not 1.8)?
Have I confused you enough with my questions?
aripantaloon, f/stops are fractions. So just like 1/2 is bigger than 1/4th, f/2 is wider than f/4. So at 18mm the widest your lens will go is f/3.5, however it can close to as small as f/22. The small end is also variable in that at 135mm it will close to as small as f/36. People rarely use f/stops this small as it can take away from image quality.
As for your question re: the f/1.8; the camera will always give you a "correct exposure" based on the light that is being read by the meter. So if your in shutter priority at 1/60th and it says that f/5.6 is correct, then thats what it will give you. If you switch to 1/30th then it will change the aperture to f/8, if you switch to 1/125th then it will change to f/4. If f/5.6 is the widest the lens will allow, then it will stay at f/5.6, the reading in the viewfinder and on the LCD will show LO and the meter reading in your view finder will show that the image will be underexposed.