When ever I go into a camera store and ask the geek squad about "depth of
field", they seem lost about the subject.So, let me ask you fellas.
I need a better digital camera. How many mega pixals. Are any special
lenses required for better depth of field?
Last, say around a price of under $400.00
Up hill slow, down hill fast, tonnage first, safety last.
"Depth of field" measures the two distances from the lens which are
acceptable in focus. For some macro focusing, that is quite small (.1" or
so). For some pinhole type cameras, they are in focus from a several feet to
infinity, but you have no control over the aperture.
To maximize dof, you need to be able to use a high f-stop (f8 or better).
You can do this by using artificial lighting (flash), shooting at long
exposure (where you will get motion blur), or you can use a high ASA (400 or
So, look for a camera with adjustable ASA (ISO), long exposure capability
(and a tripod mount), or shoot under good lighting conditions.
You don't want extreme DOF under all conditions. For example, if you are
shooting a portrait, it is frequently the case that you want the background
blurred to draw attention to the subject.
Many cameras in the $400 range will be OK for your use, but don't expect a
lot of pro capability. You'll get whatever lens comes fixed to the camera
which will likely have some telephoto capability (which reduces DOF if the
subject is close to the camera) (note, don't use any of the digital zoom
features: they pixellate your image, and you would do better to shoot with
full resolution and crop and such in photoshop (I use elements: cheap and
pretty good, or iPhoto, not bad either for the Mac).
If you want the DOF adjustments and capabilities you may be used to in a
35mm TTL camera, you are looking at more $$$ for something like the Canon
Rebel Digital which uses the Canon range of lenses; or one of the higher end
attached lens cameras from Nikon, Sony et al (I own both the Canon 20D and
Sony F717, as well as a point and shoot Sony with no features to speak of,
but it works).
Mega pixels: Most printers actually print at 300 to 600dpi, no matter what
the advertisement says (the rest is various forms of interpolation, etc.);
the dye sublimation printers used by oFoto and iPhoto (Apple uses Kodak by
the way) or the various Sony's you can buy print at about 400dpi. So a 4x6
inch print is 4MP at 400dpi; 8x10 is 12.8MP at 400dpi.
That said, I've gotten terrific looking prints from my Sony SV55 (403dpi dye
sub) and from Kodak with an old 2MP camera, as well as nice 8x10s from the
Sony F717 (5MP). So for most work, 4 to 6MP is just fine. If you do a lot of
cropping, the more pixels is better; my Canon has 8.2MP and allows for a
good deal of cropping without losing detail for a 4x6 print; but it also
allows the use of most of Canon's wide range of lenses, so framing the shot
while taking the photo is easier than a camera where you are stuck with what
came glued to it.
in article firstname.lastname@example.org, Arizona Rock & Mineral Co.
at email@example.com wrote on 12/6/05 7:22 PM:
That will buy a lot of camera. What you need to look into is how well
the manual mode of the camera can be accessed & used, to change the
shutter speed for the depth you desire.
5.0 MP would be the minimum nowadays. For special effects & maximum
flexibility, you can almost get into a digital SLR for that money.
Otherwise, get a point & shoot w/ good optical zoom.
The good digital SLR's are mostly $700 and up.
A lot can be done with the smaller, simpler, digital cameras, but don't
expect superb results when perspectives requiring great depth of field
Optics are the issue ... you need a small aperture. That implies the
ability to take a LONG exposure. You need the ability to focus CLOSE to
A ton of "megapixels" won't help if you can't focus!
On Tue, 6 Dec 2005 20:22:57 -0700, "Arizona Rock & Mineral Co."
Depth of field normally increased by stopping down, I don't know that
you're going to get any better with a digital. I don't know if they
even have a diaphram or if that's taken care of with electronics. IF
it's done with a diaphram, you might be able to force it to stop down
by really pouring on the light, as with photofloods.
If you're working close up, well... Even my best macro lenses didn't
have much. Right now I have five digitals, and the oldest, Olympus
D600-L still has the best quality, but at a kilobuck was still the
most expensive. No substitute for good lenses. Fuji has one in the
$250 range, The S-3000 that's kinda nice, but not the quality or
accuracy of exposure. Not sure of Nikon, or Kodak, don't have much
interest in either brand.
Some digitals will let you adjust the program, to force longer or
shorter exposure times, not sure how that works. Longer time means
stopped down, which hints at a diaphram.
They have to have diaphragms, because without one the lens will have
shallow depth of field. Dunno how exactly this is done: in some cheap
cameras, there's a wheel with several fixed stops rather than a real
To answer the OP's question, depth of field is *not* a function of a
better or more expensive lens; it's simply a result of stopping down
(using a smaller stop, a smaller hole). The smalla da hole, the bigger
God willing, the many crimes of the Bush Administration
will eventually be printed in a nice leatherbound,
FYI there are some programs out there that stitch multiple exposures at
different focus depths into a combined photo with increased depth of
Here's a link, check it out:
David Nebenzahl wrote:
Much depends on what you are going to primarilly take photo's of. If
it will be action shots, like trains, cars etc. you will need to look
at an Digital SLR. I have a Pentax *istD which I have no problems
with, my only regret was to not get a genuine Pentax digital lense with
Other Digital SLR's that are good, & I have seen excellent reports on
are the Canon D350 in its various incarnations, & the bottom range of
Advantage of SLR's is that you can get much better manual options. I
have made sure that I take all my photo's in RAW format, as the end
results are much better. Its a bit more of a hassle to download to
computer, but with programs such as Photoshop Elements, much of the
work can be automatically.
If its for happy snappy shots. My son has a Fuji 5.1 mp compact
camera, which I must say takes brilliant shots.
The depth of field problem is unchanged with a digital camera. You still
need a lens that can 'stop down' to very small openings ... something
like F/32 or smaller.
Ultimately, you need a 'pinhole' lens, but these have their own
problems. You can't make the pinhole much smaller the 0.020" or you
start to get unpleasant diffraction effects. I generally get best
results somewhere near f/64.
Digital cameras use shorter focal length lenses as 'normal', compared to
35mm cameras. Shorter focal length means smaller aperture for any given
"f" number, which is desirable.
I haven't tried it, but I suspect most of the usual pinhole 'tricks' can
be used with a digital camera. A removable lens is a HUGE advantage to
implementing many of these. Thus, a digital "SLR" is the most versatile.
You still need the ability to focus close to the camera ... either
'macro' capability, extension tubes, or a 'close-up' lens is needed.
These can often be used wit a pseudo-pinhole to improve results further.
The smaller size of the simpler digital cameras is an advantage,
however, in getting he camera into tight spots.
Megapixels is the least important spec for a digital camera - it matters
only if you want to make letter-size enlargements or greater, in which
case the printer will be more of an issue than the camera. In fact, two
cameras with identical MP specs may well peform quite differently. The
lens and software matter much more than megapixels.
The most important component of _any_ camera is the lens. A $400 camera
will have a good lens, other things being equal.
Ie, two 4MP cameras, each with 3x optical zoom, one at $200, the other
$400, the more expensive one should have a better lens. Ask the geek
squad about that. If they can't tell you, go to another camera store. I
find that chain stores and big-box stores are _not_ usually the best
place to buy. Go to a local, owner-operated shop, the odds are that the
owner knows his stuff much better than the minimum-wage 'droids employed
by the chains (who save loadsadough by not training their staff
properly.) The higher cost for the camera will be offset by the store
operator's knowledge eand service.
Now, about depth of field and related technical matters.
Depth of field refers to the range within which the image is in
acceptable focus. Eg, say that at 3ft, the depth of field is 10". This
means that anything within about 2'10" and 3'8" from the camera is
acceptably clear and sharp.
Depth of field depends on the three specs:
a) Distance from the lens: the further away you focus, the deeper the
depth of field.
---> In practice, this means that you should be just close enough to get
what you want in the frame.
b) The lens's focal length: a short focal length will give a deeper
depth of field than a long focal length. A wide-angle lens ("zoom out")
has a short focal length. A tele-photo lens ("zoom in") has a long focal
---> In practice, you should move in close with the wide-angle setting
rather than zooming in to get a close-up. In general, use zoom only if
there's no other way. It's often better to select the subject from
within a larger picture (to crop it) than to zoom in to the subject.
c) The aperture (opening of the lens). The smaller, the better. But
smaller aperture means less light, hence longer exposure time.
---> In practice, this means you want lots of light so the lens can be
"stopped down" (the aperture can be reduced). For model pix, that means
flood lights. Lighting is a whole 'nother subject.
NB that even with a digital camera, a good lens will be the largest
single cost item. Electronics and software are cheap compared to
In digital terms, this translates into something like the following:
-- 4MP and up
-- a 3x _optical_ zoom or better (ignore the digital zoom, it actually
degrades picture quality. Personally, I see no use for it at all.)
-- F2.8 or better (the smaller the F number, the better the camera will
perform in low light situations, which you don't want for model
photography, but do want for other subjects.)
-- an automatic macro/close-up function (reduces the need for manual
setting of aperture etc.)
-- a high quality CCD (sensor) so that the camera doesn't increase
aperture too much in low light situations.
-- as many automatically calculated exposure options as possible
(reduces the learning curve.)
If you have to choose between fewer megapixels + good lens and more
megapixels + average lens, choose the good lens.
The main advantage of digital is that you can play with the pictures, so
I also advise:
-- a 512MB or larger memory card (most cameras come with much smaller
ones than this)
-- high resolution capability (2048 horizontal minimum) -- set your
camera to this resolution, and leave it there.
-- selectable RAW and/or TIFF, and low-compression ratio JPG format.
I prefer a card reader to direct connection to the computer, so I advise
you get one of those, too.
Finally, a tripod is a excellent investment, too, especially for model pix.
Oh yeah, batteries: I prefer a camera that uses AA or AAA batteries,
since you can get those anywhere. If you get a camera that uses a custom
design, make sure that it's rechargeable, and buy a couple extras and
charger, too. I've found that my camera doesn't work properly on
rechargeable AAs, which produce 1.2V instead of 1.5V. So that's another
Warning: photography can develop into a hobby that steals time from
model railroading. How do I know? Guess!
Phil - As someone who spent more than a decade taking model RR photos
of both extreme depth-of-field and close-up, even designing my own
pinhole lenses, I can tell you straight away that no digital camera
with a price tag of under $400 is going to produce images like most of
those extreme close-up, very sharp, excellent DOF, shots often seen in
the hobby magazines. The f-ratio of the fixed (non-interchangable)
lenses employed in nearly all low end digital cameras are ill-suited to
this sort of specialized photography. Until you get up into the
category of cameras like the Canon Rebel Digital (I think Pentax makes
one now too), with prices of $800 - $1,000 range, and have the ability
to interchange lenses, you will not get the kind of results that I
infer you are looking for by the wording of your post.
I agree with much of what has already been said. In my limited
checking of smaller point and shoot digital cameras, most if not all
will only close down to around f/8. This is probably enough for most
needs for which they will be used, but will not give great depth of
field. But decent photos can be taken if enough care is taken to
ensure the main subject in the photo is in focus.
If all of the above hasn't already scared you away and you are still
looking for a decent digital, I'd look for one that has the option of
manual operations. This is where you can set the aperture (often shown
as AV - Aperture Value), shutter speed (often shown as TV - Time
Value), and most of all the focus. Some of the higher end Kodak
cameras with the 10X zoom lenses seem to have some if not all the
Bob Boudreau (shooting with Canon Digital Rebel & Rebel XT)
I get lost when they say the difference between a $200 5 mega pixel and
a $1000 5 mega pixel camera is one has a 1/4 chip and the other has a 1/2
While you need to spend around $800 for the body it always made sense to
me to buy a body for lens I already have. I have a older 35mm with lots of
good lens and will get around sometime to see if they will fit up to a new
Also it seems mega pixels somewhat relates to the size of the
enlargement you want. A 3 mega pixel camera will do a good 5 x 7 print,
etc. However if you want to summit to a mag or for a book then the rules
Well, there has been much technical discussion here about
depth of field and how to control it. By now you have
figured out that you need to have a camera that has manual
exposure controls, esp f-stop or aperature control. And a
wide range of available f-stops. f-32 to f-4 (maybe 2) should
be a good range. You may have to dig deep into a camera's
manual to determine the manual exposure capabilities since
most manufactures like to advertise the convience features
of their cameras.
I have an Olympus C-740 that has optical zoom and manual
exposure controls. Semi automatic mode allows you to select
either aperature prefered or shutter speed prefered. I have
not delved deeply into these aspects of the camera yet.
The C-740 is only a 3 megapixel camera and it has been
replaced by simular models with greater megapixels.
Certianly worth looking into.
Depending whether or not you want a lot of depth of field or only shallow
focus consider this on DOF: a smaller F number (ie f:2.0) means less DOF.
A larger F number (ie f:16) means greater DOF. A photographer would refer
to the terms larger and smaller in reverse order as an f:2.0 aperture is
much greater in area than an f:16 one. Most digitals have an aperture
priority mode which allows you to select aperture (f: value). Remember that
the flip side of f:16 is a slow shutter speed. You may need a tripod if the
light's not right.
I expect the result would be the same as asking an experienced camera store
(and I have been in several.) This is why I only went to the railroad news
group because we force our cameras to do thing unheard of in the photo
industry. I tell them about max depth of field and the staff guys look at
one another hopping someone knows the answer. I have learned from fellow
modelers and this group what is needed.
Up hill slow, down hill fast, tonnage first, safety last.
They can't tell you about maximum depth of field as a specific number
because no one does those kind of figures for a lens or camera. What I
did was when I needed a good lens for my digital slr (Canon EOS10D) was
when I went to the camera store I told the saleperson what I wanted in
terms of the areas I wanted to cover (width, depth) and we mounted up
some lenses on a body and checked. Obviously, you sound like that you
are going with a non-interchangeable lens digital, so you can't do
exactly what I did. What you can do is to try the camera by focusing on
a couple of scenes or some such in the store, press off a shot or two,
and check the dof on the lcd on the back of the camera.
Most serious photographers complain that todays digital cameras have
too much depth of field. I am not sure of the exact relation, but I do
know that digital f 8 has alot better depth of field than 35mm f 8.
This is because digital cameras use a smaller image size than 35mm. So
you don't need f 32 to get good depth of field.
Your average point and shoot digital camera will take quite good model
shots provided it has 2 things going for it.
1) adjustable exposure so that you can use a longer exposure time and
the smallest aperature available. Typically f 8...
2) some sort of macro focus capability for closeups.
Then just turn off the flash, and use a tripod to steady the camera and
you will get some pretty amazing shots.
Have a look at my online photo album.
All these shots were taken with a Canon A80 and only the available
overhead flourescent lighting.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.