SLR's viewfinder question

I know zero about dslr's but have recently been looking at the Nikon d40 and
Canon 400d.

When I look through the viewfinders on these two cameras I see a blurry
image which I cannot correct with the diopter adjustment wheel.
If I twist the lens I can get a clear image but my question is....why is'nt
the view from the viewfinder in focus all the time as it is with my point
and shoot cameras?

It seems to me, and I know I may be wrong, that at what I think is called
the wide angle that on a dslr I can do nothing to get the view in focus.
Is this something to do with the limits of what the diopter thingy can do
for MY eyes or am I just misunderstanding something.

What I'm hoping is that that it has nothing to do with my eyes or the
diopter thingy but a normal thing for a dslr but the only way I can get a
view in focus
is to twist the lens one way or the other....but either way, at what I think
is the wide end, it is always blurry.

JB

Jackson Bryan wrote:
I know zero about dslr's but have recently been looking at the Nikon
d40 and Canon 400d.

When I look through the viewfinders on these two cameras I see a
blurry image which I cannot correct with the diopter adjustment wheel.

The diopter adjustment should be set such that you can see the _indicators_
sharp (e.g the focus selectors). It has nothing to do with the focus of the
lens/picture.

If I twist the lens

i.e. adjusting the focus manually, I hope. You can also "twist" other parts
of the lens to adjust the aperture and the zoom.

I can get a clear image but my question is....why
is'nt the view from the viewfinder in focus all the time as it is
with my point and shoot cameras?

That would defeat the purpose of the view finder. You want to see the same
effect/blurriness/sharpness/depth of field as the actual photo will have.
This is essential in composing an image.

It seems to me, and I know I may be wrong, that at what I think is
called the wide angle that on a dslr I can do nothing to get the view
in focus. Is this something to do with the limits of what the diopter
thingy can do for MY eyes or am I just misunderstanding something.

What I'm hoping is that that it has nothing to do with my eyes or the
diopter thingy but a normal thing for a dslr but the only way I can
get a view in focus
is to twist the lens one way or the other....but either way, at what
I think is the wide end, it is always blurry.

That is certainly not normal.
As I mentioned: first step is to adjust the diopter (once!) to your
eyesight. It is set correctly when you can see the focus area indicators
sharp.
Then just turn on the camera, aim, and depress the shutter half-way. Then
the auto-focus should kick in and automatically 'unblurr' the image in the
view finder, regardless of wide angle or tele zoom. You can also use the
autofocus to tweak the diopter ever so slightly now.
Otherwise using the same diopter setting you should be able to focus the
lens manually now, too.

jue

On Sun, 1 Jul 2007 13:14:55 +0100, "Jackson Bryan" wrote:
: I know zero about dslr's but have recently been looking at the Nikon d40 and
: Canon 400d.
:
: When I look through the viewfinders on these two cameras I see a blurry
: image which I cannot correct with the diopter adjustment wheel.
: If I twist the lens I can get a clear image but my question is....why is'nt
: the view from the viewfinder in focus all the time as it is with my point
: and shoot cameras?
:
: It seems to me, and I know I may be wrong, that at what I think is called
: the wide angle that on a dslr I can do nothing to get the view in focus.
: Is this something to do with the limits of what the diopter thingy can do
: for MY eyes or am I just misunderstanding something.
:
: What I'm hoping is that that it has nothing to do with my eyes or the
: diopter thingy but a normal thing for a dslr but the only way I can get a
: view in focus is to twist the lens one way or the other....but either way,
: at what I think is the wide end, it is always blurry.

On a DSLR you're looking through the lens, so what you see will be blurry
unless the lens is properly focussed. My guess is that you're running your
test either with the camera turned off or with autofocus manually disabled. If
the problem were insufficient correction at the eyepiece, you wouldn't be able
to bring the image into focus by changing the geometry of the lens.

Bob

The previous repliers had some good points but one thing that is
important to understand about slrs and optical viewfinders is that when
you look through the viewfinder you are seeing the scene through a lens
that is at it's widest aperture (smallest f/ number). If you have an
f/2.8 lens then you may only have a depth of field of 12" or less in
sharp focus. It's not until you FULLY depress the shutter release that
your camera steps the aperture down (larger f/ number) and increases the
depth of field. They are designed this way 1) so that the autofocus has
as much light to play with as possible and, 2) so that you can have as
bright an image as possible in the viewfinder. Many slrs also have a
"Depth of Field Preview Button". By hitting this you can step your lens
down to the aperture you have your lens set at but don't be surprised
when your viewfinder suddenly goes dim.




Robert Coe wrote:
On Sun, 1 Jul 2007 13:14:55 +0100, "Jackson Bryan" wrote:
: I know zero about dslr's but have recently been looking at the Nikon d40 and
: Canon 400d.
:
: When I look through the viewfinders on these two cameras I see a blurry
: image which I cannot correct with the diopter adjustment wheel.
: If I twist the lens I can get a clear image but my question is....why is'nt
: the view from the viewfinder in focus all the time as it is with my point
: and shoot cameras?
:
: It seems to me, and I know I may be wrong, that at what I think is called
: the wide angle that on a dslr I can do nothing to get the view in focus.
: Is this something to do with the limits of what the diopter thingy can do
: for MY eyes or am I just misunderstanding something.
:
: What I'm hoping is that that it has nothing to do with my eyes or the
: diopter thingy but a normal thing for a dslr but the only way I can get a
: view in focus is to twist the lens one way or the other....but either way,
: at what I think is the wide end, it is always blurry.

On a DSLR you're looking through the lens, so what you see will be blurry
unless the lens is properly focussed. My guess is that you're running your
test either with the camera turned off or with autofocus manually disabled. If
the problem were insufficient correction at the eyepiece, you wouldn't be able
to bring the image into focus by changing the geometry of the lens.

Bob

On Sun, 01 Jul 2007 13:14:55 +0100, Jackson Bryan wrote:

I know zero about dslr's but have recently been looking at the Nikon d40 and
Canon 400d.

When I look through the viewfinders on these two cameras I see a blurry
image which I cannot correct with the diopter adjustment wheel.
If I twist the lens I can get a clear image but my question is....why is'nt
the view from the viewfinder in focus all the time as it is with my point
and shoot cameras?

For the very specific reason that an SLR (digital or film) shows you
exactly what the sensor (or film) is seeing.


It seems to me, and I know I may be wrong, that at what I think is called
the wide angle that on a dslr I can do nothing to get the view in focus.
Is this something to do with the limits of what the diopter thingy can do
for MY eyes or am I just misunderstanding something.

What I'm hoping is that that it has nothing to do with my eyes or the
diopter thingy but a normal thing for a dslr but the only way I can get a
view in focus
is to twist the lens one way or the other....but either way, at what I think
is the wide end, it is always blurry.

JB

Jackson Bryan wrote:
I know zero about dslr's but have recently been looking at the Nikon d40 and
Canon 400d.

When I look through the viewfinders on these two cameras I see a blurry
image which I cannot correct with the diopter adjustment wheel.
If I twist the lens I can get a clear image but my question is....why is'nt
the view from the viewfinder in focus all the time as it is with my point
and shoot cameras?

The data displayed in the viewfinder (aperture/shutter speed/ISO/focus
points) should be made sharp by adjusting the diopter control.
This focuses the eyepiece onto the focus screen.
It doesn't focus anything else.

It seems to me, and I know I may be wrong, that at what I think is called
the wide angle that on a dslr I can do nothing to get the view in focus.
Is this something to do with the limits of what the diopter thingy can do
for MY eyes or am I just misunderstanding something.

If the camera is turned off, turn it on.
Make sure the focus mode is set to "AF", it should be a switch on the
front of the camera body near the lensmount with options of M, AF (and
maybe "AFC"); it might be switch on the lens barrel instead, depending
on the brand of the DSLR camera.
Then half-press the shutter button.
The image in the viewfinder should then snap into focus (assuming that
you focused the eyepiece with the diopter control properly).
Even if it doesn't appear to be in focus, there should be a "beep"
and/or a red (or green) rectangle appear in the viewfinder (on the
focusing screen), this shows that the AF has locked onto something.
Fully press the shutter button to take a shot and then look at the
review screen on the back of the camera body.
It should show an image that has an in focus area that is roughly where
it seemed the rectangle appeared when the AF locked on.

What I'm hoping is that that it has nothing to do with my eyes or the
diopter thingy but a normal thing for a dslr but the only way I can get a
view in focus
is to twist the lens one way or the other....but either way, at what I think
is the wide end, it is always blurry.

The diopter control should only need to be used once: to get the
eyepiece lens into sharp focus with the focusing screen, to read the
data displayed and for focusing using the manual focus ring on the lens.
Depending on what sort of lens is mounted on the camera, it could have
either one (focus), two (focus and aperture or zoom) or three (focus,
aperture and zoom) adjustment rings on it.
The ring you turned might have been the aperture ring, which won't have
any effect on what you see in the viewfinder unless the "DoF preview"
button/control is activated.
Only the focus and the zoom adjustment rings will have an effect.
Focus will make the image sharper or blurrier, and zoom will make it
appear bigger and smaller.

"dj_nme" wrote in message
...
Jackson Bryan wrote:
I know zero about dslr's but have recently been looking at the Nikon d40
and Canon 400d.

When I look through the viewfinders on these two cameras I see a blurry
image which I cannot correct with the diopter adjustment wheel.
If I twist the lens I can get a clear image but my question is....why
is'nt the view from the viewfinder in focus all the time as it is with my
point and shoot cameras?

The data displayed in the viewfinder (aperture/shutter speed/ISO/focus
points) should be made sharp by adjusting the diopter control.
This focuses the eyepiece onto the focus screen.
It doesn't focus anything else.

It seems to me, and I know I may be wrong, that at what I think is called
the wide angle that on a dslr I can do nothing to get the view in focus.
Is this something to do with the limits of what the diopter thingy can do
for MY eyes or am I just misunderstanding something.

If the camera is turned off, turn it on.
Make sure the focus mode is set to "AF", it should be a switch on the
front of the camera body near the lensmount with options of M, AF (and
maybe "AFC"); it might be switch on the lens barrel instead, depending on
the brand of the DSLR camera.
Then half-press the shutter button.
The image in the viewfinder should then snap into focus (assuming that you
focused the eyepiece with the diopter control properly).
Even if it doesn't appear to be in focus, there should be a "beep" and/or
a red (or green) rectangle appear in the viewfinder (on the focusing
screen), this shows that the AF has locked onto something.
Fully press the shutter button to take a shot and then look at the review
screen on the back of the camera body.
It should show an image that has an in focus area that is roughly where it
seemed the rectangle appeared when the AF locked on.

What I'm hoping is that that it has nothing to do with my eyes or the
diopter thingy but a normal thing for a dslr but the only way I can get a
view in focus
is to twist the lens one way or the other....but either way, at what I
think is the wide end, it is always blurry.

The diopter control should only need to be used once: to get the eyepiece
lens into sharp focus with the focusing screen, to read the data displayed
and for focusing using the manual focus ring on the lens.
Depending on what sort of lens is mounted on the camera, it could have
either one (focus), two (focus and aperture or zoom) or three (focus,
aperture and zoom) adjustment rings on it.
The ring you turned might have been the aperture ring, which won't have
any effect on what you see in the viewfinder unless the "DoF preview"
button/control is activated.
Only the focus and the zoom adjustment rings will have an effect.
Focus will make the image sharper or blurrier, and zoom will make it
appear bigger and smaller.

On a point and shoot camera the viewfinder is a much simpler optical device
that doesn't need to be focused.


The advantage of a SLR is that you can control what will eventually be the
finished picture.

On Sun, 1 Jul 2007 13:14:55 +0100, Jackson Bryan wrote:

If I twist the lens I can get a clear image but my question is....why is'nt
the view from the viewfinder in focus all the time as it is with my point
and shoot cameras?

Assuming the diopter adjustment is correct for your eye, it should be
sharp, at least the *viewfinder*. The lens image might be blurry if it's
out of focus, but the viewfinder items should be sharp. When you make
the diopter adjustment, look at the focus points, any status indicators,
etc. to be in sharp focus - i.e., the "non photo" things you see. Then
focus the lens itself and it all should be sharp.
--

---- Len Philpot -------- l e n @ p h i l p o t . o r g (no spaces)
------- ------------- http://pages.suddenlink.net/lenphilpot/

John wrote:
On a point and shoot camera the viewfinder is a much simpler optical device
that doesn't need to be focused.

Most P&S cameras made today have no optical viewfinder at all and rely
totaly on a liveview LCD on the rear of the body as the only viewfinder.
That's why you see so many people holding digicams out at arm's length
taking pictures.

The advantage of a SLR is that you can control what will eventually be the
finished picture.

As you can with any camera that has any sort of viewfinder.
That's what it's there for.

dj_nme wrote:
John wrote:
The advantage of a SLR is that you can control what will eventually
be the finished picture.

As you can with any camera that has any sort of viewfinder.
That's what it's there for.

Well, no.
There are many problems with separate view finders, i.e. non-SLR:
- you do not have a way to check DOF
- you got the parallax problem
- synchronizing zoom functions between viewfinder and lens is a challenge at
best and some cameras even have a frame in the view finder to indicate which
area of the viewfinder is relevant for long zoom
- focus adjustments are meaningless because you cannot observe the results
through the actual lens
- ...

I am sure people who are more experienced than me can come up with many more
reasons.

jue