Richard wrote:
Would you be willing to visit and take a more
comprehensive set of
detailed pictures?
I would if I had a digital camera. Looks like bear has it covered anyways.
I've been wanting to get a digital camera but have to work up the enthusiasm
to brave the shopping malls.
I don;t havea digital camera either. It makes absolutely no sense for me
to get one. If I bought a digital camera, I'd also haev to buy a modern
computer, the equipment to maintain that computer, software, and the
like. And I'd probably have to upgrade various bits of it every couple of
years -- more expense.
Now, much is made of the fact that digital photographs are cheaper than
film photographs. Probably ture until you consider those upgrade costs as
well (A good film camrera will go on for decades without problems). At
that point you realise you have to shoot an awful lot of film to make it
worthwhile.
I've also yet to see a digital camera that comes close to the qualtiy of
results from my film cameras. I am not talking about apparent sharpness,
that can be tweaked. I am talking about detail in the image.
Most high-steet film processing 'minilabs' can put your inmages onto CD
for a nominal extra charge. The scans aren't great, but I always get the
CD anyway. That way, I have the film negatives, which I can always print
myself or rhave sanned at a higher resolution, I also have the machine
prints and the CD whoch is probably adequate for web pages, etc. And the
place I use takes 30 minutes to process and print the flim and burn the
CD. Hardly that long.
Anyway, rant over...
Which reminds me I have a question for camera buffs.
If I can justify asking this here, the main motivation for getting a
camera is taking pictures of old equipment for addition to web pages. I'm not
into photography in a big way, in my life I've probably taken more photos for
tourists ("take photo please, just press button") than I have for myself.
My main concern for taking close-up (oblique, not just plan view) photos of
equipment is depth-of-focus. I know/figure it's mainly a function of aperture
You mean depth of field. Depth of focus refers to the allowable error in
the postiion of the image plane (film), not the object plane.
size (smaller --> longer depth-of-focus) and
(optical) zoom (to minimize the
ratio of focus-depth to lens-to-object distance). (And smaller aperture means
less light which requires longer exposure.)
True. The log expsore shouldn't be a problem though. Arrange a stand for
the camera, fix the object and the ligthing (I made a copying stand from
n old enlarger and some metal bar). I routinely use exposures of 1s or
longer for this.
LEns resolution is worse at very small apertures due to difraction
effects. But for close-ups where depth of field is limited anyway, keep
the lens stopped down (smallest aperture).
You want a camera that gives you manaul control over the aperture
setting. I am told some cheaper digital cameras are auto-only, and are
unlikely to be very suitable. More expensive ones certainly do have such
control.
Depth of field doesn't actually exist, if you think about it. There is
exactly one object distance that gives a sharp image on the film for a
given lens position (focus setting). The only reason that you get an
apparent depth of field is that small circular areas on the final print
look like perfect points when viewed by the human eye at normal viewing
distances. If you have each point blurred out to, say, 1/1000", it'll
still look sharp.
Now, actually, digital cameras can do better heer because of the more
limited resolution of the sensor compared to good film, and the image
processing you can apply. If the blur (the technical term is 'circle of
confusion' is smaller than the size of a pixel on the image sensor, it's
sharp.
The right way to get better depth of field for oblique shots is to tilt
the lens (!). There's a well known principle, the name of which I can
neither spell nor pronounce that basically says the image plane (film),
subject plane, and a plane throughthe centre of the lenx perpendicular to
the optical axis should all interstect in the smae line. The problem is
that no digital camera has a tilting front. Few film cameras do either
other than large-format (5*4" sheet film) technical cameras, which to be
honest are not what I'd recomend to you. They produce excellent results,
but they take a lot of practice to use properly, you need a darkroom, and
so on. Yes, there are digital backs for them, but you want to sit down
before hearing the price (_Way_ more than the cost od a decent car, for
example).
If I have the above principles about right, the practical question(s) are:
Is your typical $200 / 3*-optical-zoom / 5-MPixel camera good for this or
does one have to go to something higher end with a special lens, etc.?
I think you want something a bit higher-end than that, but I might be
wrong.
Personally, I'd want interchangeable lenses (extreme close-ups are one of
the times when this is useful, not just for fitting special lenses
corrected for short object distances but also to be able to extend the
lense further from the vamera).. I'd also want full control over the
various settings, in particular manual focus and aperture controls.
It's subjective as to what's adequate of
course, but I'd be interested in
opinions.
That said, it deptend on what you want to do with the photos. If you want
to just keep a record of how something wnnt together, how the cables were
routed, and so on, then just about anything will do if it can focus close
enough. Similarly, you probably don't need anything special if you want
to put pictures oan a web page so you can point out compoents on the PCB
that are inovled in a particualr function amd which you had to test as
part of a repair.
-tony