Nikon D70s out of focus

Hi
I have a D70s and a Nikon 18-200 lens. When the lens is at the wide
angle end (most notably 18 mm) the camera focuses at about 2 or 3
meters. Thus anything in the distance will be slightly blurred, at least
when viewed full size. I always have to zoom to 200 mm and focus and
then bring it back to 18. Is this normal? It is inconvenient at the very
least.
TIA
Alex

On 2007-12-08 07:50:45 -0800, AlexE said:

Hi
I have a D70s and a Nikon 18-200 lens. When the lens is at the wide
angle end (most notably 18 mm) the camera focuses at about 2 or 3
meters. Thus anything in the distance will be slightly blurred, at
least when viewed full size. I always have to zoom to 200 mm and focus
and then bring it back to 18. Is this normal? It is inconvenient at the
very least.
TIA
Alex

It is not normal. Something is wrong with your autofocus.
--
Waddling Eagle
World Famous Flight Instructor

C J Campbell wrote:
On 2007-12-08 07:50:45 -0800, AlexE said:

Hi
I have a D70s and a Nikon 18-200 lens. When the lens is at the wide
angle end (most notably 18 mm) the camera focuses at about 2 or 3
meters. Thus anything in the distance will be slightly blurred, at
least when viewed full size. I always have to zoom to 200 mm and focus
and then bring it back to 18. Is this normal? It is inconvenient at
the very least.
TIA
Alex

It is not normal. Something is wrong with your autofocus.


Goddamn right something's wrong. Same thing with the original lens 18-70
mm.

"AlexE" wrote in message
...
C J Campbell wrote:
On 2007-12-08 07:50:45 -0800, AlexE said:

Hi
I have a D70s and a Nikon 18-200 lens. When the lens is at the
wide angle end (most notably 18 mm) the camera focuses at about 2
or 3 meters. Thus anything in the distance will be slightly
blurred, at least when viewed full size. I always have to zoom to
200 mm and focus and then bring it back to 18. Is this normal? It
is inconvenient at the very least.
TIA
Alex

It is not normal. Something is wrong with your autofocus.


Goddamn right something's wrong. Same thing with the original lens
18-70 mm.
And of course you sent the camera & lens to Nikon's Service Dept. to
check it out?

AlexE wrote:
I have a D70s and a Nikon 18-200 lens. When the lens is at the wide
angle end (most notably 18 mm) the camera focuses at about 2 or 3
meters. Thus anything in the distance will be slightly blurred, at
least when viewed full size.

Yes, that is called Depth of Field and depending upon how you want to design
your photos it can be very desirable or a curse. If you want to have both,
the foreground at 2m and the background in the distance, in focus then you
need to use a small apperture like maybe f16 or f22.

jue

AlexE wrote:
Hi
I have a D70s and a Nikon 18-200 lens. When the lens is at the wide
angle end (most notably 18 mm) the camera focuses at about 2 or 3
meters. Thus anything in the distance will be slightly blurred, at least
when viewed full size. I always have to zoom to 200 mm and focus and
then bring it back to 18. Is this normal? It is inconvenient at the very
least.
TIA
Alex

Well, in contrast to the other posters, I think your lens is quite
normal. I am a Canon man, and my main lens is a 17 - 85 mm, not quite
the same range as your 18 - 200, and it exhibits a similar scale error
between wide angle and the long end.

The reason is that is extremely difficult designwise to arrange the
scale to be accurate over the zoom range, and since focusing is
predominantly automatic, it doesn't really matter. Unlike older,
especially non-zoom lenses, precise scaling on slr camera lenses with AF
is neither achievable nor necessary. It is at best an indicator only,
not to be relied on to focus by if you want precise focus.

One thing that *is* wrong is your focusing at full zoom and then zooming
back to your required length. This is because zoom lenses are not
designed to maintain focus while zooming, so focusing at the intended
zoom setting is necessary - which your AF does. If you focus at full
zoom and then zoom back you can practically guarantee an out-of-focus
picture. I say 'practically' because DoF can mask small degrees of
misfocus - but if you shoot wide open you will soon see the difference.

Colin D.

--
Posted via a free Usenet account from http://www.teranews.com

Colin_D wrote:

One thing that *is* wrong is your focusing at full zoom and then zooming
back to your required length. This is because zoom lenses are not
designed to maintain focus while zooming, so focusing at the intended
zoom setting is necessary - which your AF does. If you focus at full
zoom and then zoom back you can practically guarantee an out-of-focus
picture. I say 'practically' because DoF can mask small degrees of
misfocus - but if you shoot wide open you will soon see the difference.


On the contrary, a true zoom lens *will* maintain correct focus
throughout the zoom range. A lens that does not do this is correctly
termed "varifocal".

My SMC Pentax-A 35-105mm f/3.5 (constant) manual focus lens is
varifocal. The focus varies significantly throughout the zoom range.
It doesn't matter too much because it's a one-touch lens, with a
combined zoom/focus ring, but the change in focus is fairly dramatic.

But there are benefits - optically, the lens is a fine performer. The
combination of excellent sharpness and smooth bokeh would have been
almost impossible to obtain in a true zoom of the same focal length
range and maximum aperture.

http://www.focustestchart.com/chart.html


On Dec 8, 8:50 am, AlexE wrote:
Hi
I have a D70s and a Nikon 18-200 lens. When the lens is at the wide
angle end (most notably 18 mm) the camera focuses at about 2 or 3
meters. Thus anything in the distance will be slightly blurred, at least
when viewed full size. I always have to zoom to 200 mm and focus and
then bring it back to 18. Is this normal? It is inconvenient at the very
least.
TIA
Alex

Tony Polson wrote:
Colin_D wrote:

zoom lenses are not designed to maintain focus while zooming, so
focusing at the intended zoom setting is necessary - which your
AF does. If you focus at full zoom and then zoom back you can
practically guarantee an out-of-focus picture.

On the contrary, a true zoom lens *will* maintain correct focus
throughout the zoom range.

The term you are looking for is "parfocal".

A lens that does not do this is correctly
termed "varifocal".

Every lens that changes focus length is commonly called "zoom",
and even the action of changing the focus length is often called
"zooming". Then there are "18x super zoom" cameras.

-Wolfgang