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01/19/2006 11:58:22 AM · #1
Hello, I was wondering if anyone can tell me the diffrence between the fstop of the lens vs the fstop of the camera. MY Kodak P850 specs tell me that the lens is 2.8-3.7 but the camera can shoot 2.8 to 8.0 I know this may be a basic question but any help would be appreciated.
01/19/2006 12:01:00 PM · #2
When you zoom, the widest possible aperture will change from 2.8 to 3.7
The narrowest is 8 no matter how far you zoom in/out.
01/19/2006 12:01:28 PM · #3
Is the Kodak P850 a camera?

The 2.8-3.7 might be related to the zoom of the camera, IOW, when zoomed wide, it's max aperture is 2.8, but when zoomed tight, it's max aperture is 3.7.

This is just a guess...

<edit> too slow...

Message edited by author 2006-01-19 12:01:52.
01/19/2006 12:15:36 PM · #4
Thanks Psychephytax,
So if I understand... the camera range of f stops will be limited by the f stop of a particular lens?
01/19/2006 12:18:20 PM · #5
Originally posted by slingshot:

Thanks Psychephytax,
So if I understand... the camera range of f stops will be limited by the f stop of a particular lens?


yes. Some lenses close down to f64 whereas others are limited to f22.
Some lenses open up to 1.8 whereas others can only open up to 5.6. Lens with apertures around 2 are considered fast lenses.
01/19/2006 12:19:17 PM · #6
Originally posted by slingshot:

Thanks Psychephytax,
So if I understand... the camera range of f stops will be limited by the f stop of a particular lens?


Yes.
01/19/2006 12:20:26 PM · #7
Originally posted by slingshot:

Thanks Psychephytax,
So if I understand... the camera range of f stops will be limited by the f stop of a particular lens?


HUH?

If you start at the widest zoom setting, your brightest aperture will be f2.8, when zoomed in to the telephoto setting the brightest aperture will be f3.7 . At any zoom setting the smallest aperture available is f8.

01/19/2006 12:21:03 PM · #8
Originally posted by slingshot:

Thanks Psychephytax,
So if I understand... the camera range of f stops will be limited by the f stop of a particular lens?


That's correct; the f/stops are integral to the lens, they have nothing to do with the camera body itself.

To expand a bit further, f/stop is defined as the ratio of the physical diameter of the aperture and the focallength of the lens. A 25mm aperture on a 50mm lens is f/2.0; the same 25mm aperture on a 200mm lens would be f/8.0. Zoom lenses that have a fixed maximum perture have a "floating" widest f/stop, as the ratio itself changes as the lens is zoomed from short to long. More expensive lenses often have a variable maximum aperture so the widest f/stop remains constant throughout the zoom range. My Canon 70-200mm f/4L has a maximum f/stop of f/4.0 throughout its range, as does my Tamron 28-57mm f/2.8...

R.
01/19/2006 12:27:47 PM · #9
Originally posted by Spazmo99:

Originally posted by slingshot:

Thanks Psychephytax,
So if I understand... the camera range of f stops will be limited by the f stop of a particular lens?


HUH?

If you start at the widest zoom setting, your brightest aperture will be f2.8, when zoomed in to the telephoto setting the brightest aperture will be f3.7 . At any zoom setting the smallest aperture available is f8.


I'm not sure this is true; on lenses with fixed physical apertures (hence floating f/stops) I believe the smallest f/stop ALSO changes. I think this particular lens will be f/8 at its wide end and f/10.5 at its tele end.

I'm not 100% sure of this, however... KIRBIC! Calling Dr. Kirbic, please!

R.
01/19/2006 01:27:28 PM · #10
Originally posted by Bear_Music:

That's correct; the f/stops are integral to the lens, they have nothing to do with the camera body itself.

To expand a bit further, f/stop is defined as the ratio of the physical diameter of the aperture and the focallength of the lens. A 25mm aperture on a 50mm lens is f/2.0; the same 25mm aperture on a 200mm lens would be f/8.0. Zoom lenses that have a fixed maximum perture have a "floating" widest f/stop, as the ratio itself changes as the lens is zoomed from short to long. More expensive lenses often have a variable maximum aperture so the widest f/stop remains constant throughout the zoom range. My Canon 70-200mm f/4L has a maximum f/stop of f/4.0 throughout its range, as does my Tamron 28-57mm f/2.8...

Robert, I love it when you explain technical stuff such as this. You make it sound easy. Thanks (In case you don't get enough kudos...).
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