Nikon lens aperture question

[james_martin9]

I hope this is simple. I have a D70 with the 18-70 3.5-4.5 lens. in M

mode the camera allows me to set the aperture up to f22. Is this

normal and if so how do f-stops beyond those on the lens affect the

picture. I.E. zoomed to 70mm which should be f-stop 4.5 with the

camera set to f22

[jpfy32]

The aperture is a way of contoling how mich light passes through the lens. There is a tutorial at http://www.photo.net/learn/making-photographs/exposure which explains it in more detail

[verdellnazgul]

The range you see on the lens is actually the maximum opening range. For zoom lenses, most have a range for the max aperture. Prime or non-zoom lenses will not have a range, only the max. Some lenses will have the complete range on the aperture ring (used for setting the aperture manually which your lens does not have.) This means that the max at 18mm (the widest angle) is f3.5 and the max at the longest focal length of 70mm is f4.5 when you zoom it out. Your actual complete f-stop range for this lens is f3.5 - f36. I believe with the d70 you can pick any f-stop inside that range in 1/3 stop increments.

 

The manufacturer chose to put the max range on the lens as this relates to how "fast" the lens is and is what most people will be interested in.

 

As far as how it affects it the picture, the max apertures will give you a narrow or shallow depth of field and the minimum openings will give you a deeper depth of field. Shout back if this doesn't answer your questions.

 

Steve

[alan_olander1664878205]

The maximum aperture at 18mm is 3.5, but the maximum aperture at 70mm is only 4.5. The minimum aperture is 22 throughout the zoom range. Some zooms (the expensive ones!) have the same maximum aperture at all zoom settings. The aperture (f/stop) controls the amount of light entering (along with the shutter speed), and the depth of field.

[frank uhlig]

James, I hope you are not confused by the backwards f stop convention: they are ratios of focal length/opening diameter and f/4.5 is way larger than f/22 (by about 4 2/3 stops), though the number 22 is larger than 4.5. We photogs live "backwards" sort of. Good luck.

[verdellnazgul]

Sorry about the typo James. As Alan said, your min throughout the zoom is 22 and the min at 70mm is f29. I don't know where 36 came from.

 

Steve

[alan_olander1664878205]

I wasn't exactly correct in what I said. Like Steve said, the minimum at 70mm is f/29. Both the minimum and maximum aperture varies with the zoom setting. You'll have to study up on lenses to learn why! ;)

[james_martin9]

Duh, I remember the backwards aperture thing now. But yall still answered my question about the range on the lens being the maximum. Thanks guys!