question about lens

[rebel]

Howdy! I am buying a D70s w/ Kit Lens, I have a question about the kit lens:
18-70mm f/3.5-4.5 G-AFS ED-IF DX Autofocus Lens
the f/3.5-4.5 is the aperture settings, But is that the maximum range? or is that the minimum aperture that can be used on the lens.

Thanks ahead, sorry if it's a silly question.

[frink]

Not a silly question

f/3.5-4.5 are maximum apertures possible at 18mm to 70mm

So maximum apertures are f/3.5 @ 18mm and f/4.5 @ 70mm. Minimum apertures for that lense are f/22 @ 18mm and f/29 @ 70mm.

[MHD]

Yes, that is the minimum f-stop
ie at 18mm it is f/3.5 and at 70mm it is f/4.5

I seem to recall the maximum f-stop being f/22

[leek]

well... I started typing an answer, but while I was typing - 2 other answers were posted...

What they said...

[rebel]

Thanks! I was just a bit confused about the range.

f/3.5-4.5 is when the lens is allowing the minimum amound of light to pass through? Allowing for a shallow DOF, correct? Would i have to increase the exposure time for proper exposure? (as the f/ decreases, should I increase the exposure time?)
What is a good exposure time when holding the camera in my hands? I don't have a tripod for it yet, and those things are bulky and hard to carry around too.


and at f/22 I will be able to focus to basicly infinity?

[gstark]

Thanks! I was just a bit confused about the range.

f/3.5-4.5 is when the lens is allowing the minimum amound of light to pass through?

No. the lower the numeric value (1.4, 2.8, 3.5, etc) the greater the amount of light that can pass through the lens.

So, 1.4 is a larger hole through the lens and permits more light than 2.8, which is a larger hole through the lens and permits more light than 3.5, and so on. F22 is generally a quite small hole, and permits a lot less light than the other numbers I've mentioned.

But

Allowing for a shallow DOF, correct?

Yes.

So ...

1.4 = large opening, lots of light, shallow DoF.

F8 = Smaller opening, much less light, greater DoF.

F22 = Smaller opening again, still less light, greatest DoF.

Would i have to increase the exposure time for proper exposure? (as the f/ decreases, should I increase the exposure time?)

For any given EV, you will find that you would need to increase the exposure time (shutter speed) as you move from an aperture of F1.4 through F8 and into F22.

What is a good exposure time when holding the camera in my hands? I don't have a tripod for it yet, and those things are bulky and hard to carry around too.

They certainly can be. The rule of thumb is to use a shutter speed no greater than the reciprocal of the focal length in use. Thus ...


50mm lens = 1/50 sec (or faster - 1/125, 1/250, 1/500)

200mm lens = 1/200 sec (or faster - 1/250, 1/500)

500mm lens = 1/500 sec (or faster - 1/1000, 1/2000)

and at f/22 I will be able to focus to basicly infinity?

Don't count on it. you need to mindful of where the subject matter that you're trying to capture really is. If it really is a long way away, then yes.

But if it's just a few feet away, chances are that even at F22, your lens's available DoF won't let you get away with that.