FAQs: Focusing with the Panasonic FZ1/FZ2
This is an
updated version of the document originally posted in November 2003.
It is intended for FZ1/FZ2 users, but much of it will apply equally to
later FZ cameras when autofocus is used. Photos
are now included to illustrate particular points.
In the interests of keeping the file size manageable, all images have
been downsized to 400*300 pixels. Image
quality is not therefore representative of the full sized pics.
Many thanks
(again!) to Fred Moore for his suggestions, and for hosting this document on his
website.
Why is
focusing a problem with this camera?
It isn't
always. If you use it like a
"normal" point-and-shoot camera up to 3 or 4 times zoom, then there is
little to complain about. For
example, this shot of the pavilion at Lord's cricket ground was at around 2
times zoom. With bright light and
plenty of contrast, the focus is fine.
However, this
camera has an unusually long zoom (up to 12 times), with a maximum aperture of
F2.8 constant over the entire range. These
features, along with the optical image stabiliser, are what makes the FZ1/FZ2
(and other cameras in the FZ range) special, but they can result in a very
narrow depth of field.
For an
explanation of "depth of field" and why it's important, see Phil
Askey's article on the dpreview website:
http://www.dpreview.com/learn/Glossary/Optical/Depth_of_field_01.htm.
A narrow DOF is not necessarily a bad thing, and is often used to make a
subject stand out against a blurred background. Indeed, the FZ1/FZ2's Portrait mode is intended to create
this very effect.
However, with
a narrow DOF, accurate focusing becomes critical.
New users
naturally tend to start using the camera's long zoom immediately, and are often
disappointed with first results, especially if taken indoors in poor light.
Unfortunately, unlike the later FZ cameras, there is no manual focus or
"focus-assist" feature to help, so care is needed to obtain
consistently good results.
Hence the
various hints and tips offered here.
Are there
any differences between the FZ1 and FZ2 when focusing?
When the FZ2
appeared, some users thought that it was faster in focusing.
I can't quantify it, but it does feel "snappier".
I carried out some side-by-side tests a few months back, but I found no
consistent difference in results as far as accuracy of focus was concerned.
How does
the camera actually focus?
The camera
uses a contrast detection system. It tries to find the focus setting which gives
the highest contrast within the focusing area.
·
It looks for vertical
contrast. If you have a subject with strongly defined vertical lines, then it
will find a good focus.
·
If, however, there
are only horizontal lines, or no areas of contrast at all, then it will find it
difficult to focus.
·
If you have only
horizontal contrast, then rotate the camera to focus, then rotate it back to
take the picture.
What
conditions are likely to cause focusing problems?
Combinations
of low light and use of the long zoom create most problems.
·
In low light
conditions, the aperture opens wide, and the depth of field is narrower.
·
It is also narrower
at extreme zoom settings.
·
These situations can
be aggravated by using the Portrait mode.
·
Similarly, manually
setting the ISO to 50 or 100 can also force a wider aperture than the camera
would select if the ISO value were set at automatic.
·
Using macro mode at
wide angle very close to the subject also results in a very narrow depth of
field, often limited to a few millimetres.
·
While filters have no
adverse effect, shooting through windows can sometimes confuse the system,
especially when wet, dirty, or at an angle.
·
If the focusing area
includes lots of sharply defined objects at a different distance from the
subject, the camera tends to focus on those instead of the subject.
For instance, in this pic, the camera has focused on the leaves on the
ground, rather than the flower.
How do I
know if my shots are in focus?
The question
is not as silly as it sounds. With
a good focus, the subject should appear sharp and clearly defined using the
viewing software on your PC, zoomed right up to the point where you can see the
pixels. However, by now you are
back at base, with no chance to do a retake.
As it happens,
the FZ1/2 has a very good review mode, which enables you to zoom up in camera,
up to 8 times in record mode, and 16 times in play mode.
Where there is any doubt about focus, it's easy to do an immediate quick
check as a matter of routine. It's
a simple matter to delete and try again, if necessary.
I thought
my pics were badly focused, but others have told me it was due to camera shake.
How do I tell camera shake from bad focus?
Bad focus
shows as a general fuzziness or lack of definition.
However, it
can be confused with camera shake. Leaving
aside Night Portrait mode, the FZ1 allows you to take hand-held shots down to
1/8th second. (The FZ2
will let you go lower than this if you use the priority modes.)
The 1/8th second limit is well chosen, since it is possible
(with the optical stabiliser and a steady hand) to take good shots at this
speed, but difficult at slower speeds than that.
Camera shake
shows up as a kind of consistent streaking effect, best seen if there are points
of light in the pic. (Note that
this shot was specially taken to illustrate the effect.
With the OIS engaged, I had to work really hard to make it happen, even
at 1/8th second!)
Why are
some objects blurred while others are in focus?
This is almost
certainly due to "motion blur", when the shutter speed is too slow to
freeze the action. This (greatly
magnified) detail from an indoor scene in poor light gives an example.
It's an awards ceremony. Most
of the objects are in reasonable focus, but the 1/13th shutter speed
was too slow to stop the movement of the certificate being handed over.
For this reason, users are often disappointed with attempts to photograph "all action" sports shots under artificial light. The long zoom is tempting, but the maximum ISO of 400 is just too slow to allow a fast enough shutter speed. In this situation, use burst mode and see whether any of the shots capture the major subjects while they are stationary.
Failing that,
underexpose by 1 or 2 stops. This will increase the shutter speed, but you
will have to lighten the pic in post processing.
I see that
there are several options for focusing. How
do they differ, and when do I use a particular method?
·
First, from the AF
Trigger menu, you can select "shutter button" focus, and this is
probably the most generally useful, and the most familiar to digital camera
users. In this mode, the camera
will focus when you half-press the button.
A small green light flashes as the system tries to focus.
If the camera thinks it has a good focus, the light will stop flashing
and stay on. Then you can fully depress the button to fire the shutter.
This mode allows you to focus on the subject when it is not in the centre
of the frame, and then reframe and fully depress the button to take the picture.
If the green light continues to flash, you don't have a focus, so you
release the button and try again, perhaps on another part of the target, or on
another subject at the same distance. Be
aware that fully depressing the button without waiting for a focus lock will
cause a delay while the system focuses. You might think that the shutter has
fired and move the camera prematurely, and this could result in camera shake.
It’s also worth remembering that the focus mechanism seems to pick up
where it left off. That is, the
closer the last focus to the new subject, the quicker it will focus.
So it might be worth doing a quick "test focus" (depressing the
button half-way, getting a focus, then releasing the button) on start up, or
when the scene changes significantly. This
will considerably reduce the focusing time.
·
Next, you have a
"continuous autofocus" option. When this is set, operation is the same
as “shutter button”, except that the camera is always trying to find focus,
regardless of whether you are actually trying to take a picture or not.
You can hear the mechanism working as you move the camera around.
When you take a picture, it finalises the focus and the shutter fires.
This mode is useful when you're taking a number of candid shots, and you
need a quick focus with acceptable results most of the time.
This mode is forced when you're using Simple (heart) mode.
The manual recommends this mode when you are asking someone else to take
a picture of you, presumably on the basis that you may not want to give a
lecture on digital camera focusing techniques beforehand!
The downside is that the working of the focus mechanism uses power -
"The battery consumes early," as the manual quaintly puts it.
·
And then there is a
prefocus mode. Select
"Focus" on the AF Trigger menu. This
is the nearest the camera comes to a manual focus.
With this option selected, you can point the camera at a subject at the
distance you require, and press the focus button on the back of the camera.
Once you have a good focus, the green light comes on as usual, and the
focus setting is unchanged until you press the focus button again. This mode is somewhat clumsy to use (a dedicated button to
select it would have been better than a menu option), but it's very useful for
fast moving objects where it's going to be difficult to get a fix, or when you
are taking successive pictures of subjects which are likely to be at a similar
distance, such as at air displays, for instance. Focus on objects like the control tower, or a building across
the runway, or even on low cumulus clouds with well-defined vertical edges.
The prefocus setting is retained even if you change modes, but is lost if
you set Simple mode, which engages continuous autofocus, or when you use Night
Portrait mode. It is also lost if you turn the power off, or if the power
save kicks in. This is a bit of a
nuisance if, as at air displays, nothing is happening for long periods.
You can turn the power save off, but then battery life becomes an issue.
You can get a
good idea of how each these modes works by trying each of them with the
self-timer, and watching what happens after the interval period. Using the normal shutter button mode, you can see the focus
extend or retract, overshoot, home in, get a fix, and then fire the shutter.
This can take up to a second, depending upon how much work it has to do.
Using the continuous autofocus, the focusing is already most of the way
there, and the delay is much shorter. Using
prefocus, there is no focusing delay at all.
(By the way,
using the self-timer is very good for taking static subjects.
It totally avoids "shutter drag", that is, shake due to
pressing the shutter itself!)
What is the
difference between normal and "spot focus"?
Normally, the
camera tries to focus on the area in brackets in the middle of the EVF or LCD.
·
If the subject is not
within the brackets, you can frame the subject, prefocus or half press the
shutter to get a fix, and then reframe and take the picture.
·
If
the subject is competing for focus with a high contrast object, you can
do the same to exclude the unwanted object from the focus area.
This works
fine, except when the subject matter occupies only a small part of the focusing
area. A typical example would be a
single small flower (as in the earlier shot).
In this case, you can select spot mode from the menu.
With this set on, the area being measured in the display is much smaller,
so you can be more selective.
Note that with
spot mode set, the camera also measures exposure from this reduced area.
This works well for a number of subjects, such as aircraft in flight (and
the moon!). However, it can happen
that you get a good focus on the subject, but the picture can be either under-
or over-exposed. In order to avoid
this, you can:
·
Try to position the
spot area on a part of the subject which is more representative of the overall
required exposure, or
·
Use the AE bracketing
feature which lets the camera take three successive shots at different exposure
values which you can set, or
·
Use prefocus and spot
mode to get a focus, and then switch back to normal metering to take the
picture.
What are
ISO settings, and how do they affect focusing?
Which should I use?
ISO settings
allow you to vary the sensitivity of the camera to light, in exactly the same
way that you can use “slow” (low ISO) or “fast” (high ISO) film with
film cameras. The great thing about
digital cameras is that you can vary the ISO setting from shot-to-shot, or leave
the camera to decide the setting itself depending upon light levels.
ISO settings
are a subject of constant debate on the various forums. At the heart of the matter is the fact that at higher ISO
levels, especially 400, pics can appear noisy/grainy, just as they can with film
cameras using “fast” film.
Broadly, there
are two schools of thought.
·
The
"perfectionists" insist on using ISO 50 or 100 at all times, as indeed
do some of the reviewers when taking sample images.
The downside is that forcing low ISO settings can open the aperture and
create focusing problems, as well as possibly underexposing pics, and even (with
the FZ1) making the EVF or LCD viewfinders difficult to use in very low light.
·
The
“pragmatists”, on the other hand, leave the ISO setting on automatic.
This makes the camera and viewfinder usable under most lighting
conditions, and makes focusing easier. True,
in low light situations, the camera may select ISO 400, and noise can appear.
However, with the FZ1 and FZ2, this is normally only noticeable in areas
lacking in detail, and may not even be noticed at all by non-expert viewers,
especially on a print. If you wish,
you can minimise the effect in advance by taking the pic with the "picture
adjustment" set to “natural”. This
softens the image and reduces the noise at the expense of losing fine detail.
·
Alternatively, you
can wait and see whether there really is a problem with the pic.
You can then use software to reduce the noise.
If your software does not have a noise reduction function, there are at
least four specialist pieces of software which do, and each has versions for
personal use which may be downloaded free of charge.
Helicon
Filter from http://helicon.com.ua/pages/index.php?filter
Neat
Image from http://www.neatimage.com
Noise
Ninja from http://www.picturecode.com/
Noiseware
from http://www.imagenomic.com/
I have used
both Neat Image and Noiseware, and both give good results, with Noiseware
especially fast in operation.
In order to
show the effect clearly, I had to seriously crop and enlarge these examples.
The difference is not that noticeable when viewed on screen at normal
size.
This
is an area from the original taken at ISO 400.
This is the
same area from the pic after processing by Noiseware using default settings.
So, in
summary, what do you recommend to obtain consistently good focusing?
·
Try to work in good
light. This will keep the aperture
closed up and increase the depth of field.
·
Use the long zoom
sparingly. Using wide angle
increases depth of field.
·
Choose which focusing
mode is best for what you're trying to do. For ad hoc candid shots, continuous autofocus works well.
For a number of shots of subjects at the same distance, use prefocus.
Otherwise, use the shutter button. In
each case, consider whether spot mode might help.
·
Be sensible about ISO
settings. What is your priority?
Guaranteed noise-free pics, or getting the shot?
If the latter, leave the ISO on automatic, and do any noise reduction
later if you really need to.
·
Finally, and probably
most importantly, be patient. Spend
time learning about the camera, and don't be afraid to experiment.
These remarkable little cameras are well thought out, and the results can
be very rewarding. Take the time
and trouble to obtain a good focus in difficult conditions.
Check each shot immediately, and don't hesitate to delete and try again.
Dud shots cost don't cost you a penny!
Good shooting!
(I have no
connection with Panasonic, or with the suppliers of noise reduction software
mentioned here.)