You are basically trying to perform a production process and are in need
of consistency as well as correctness. I see several problems that
prevent you from getting correct and consistent output.
1) variable light intensity
2) variable light color
3) inaccurate color balance to correct #2
4) over-sharpening and contrast too high
Your first two problems stem from trying to use natural and overcast
daylight. First it limits when you can do your work and secondly it is
never really the same brightness or color from session to session or
even within the same session.
Although the camera is probably getting the color mostly right you're
not giving it as much help as you can. If you look at an RGB histogram
of your gray sheet backgrounds you will see that, although they *might*
be 18% reflectance they are not particularly good white balance targets
since they do not have equal brightness levels between the red, green
and blue channels. Furthermore, it appears that you are depending on
the camera to set white balance for each exposure which also includes
the shell casing you're trying to shoot. Just as a reflected light
meter can make errors due to the varying reflectivity of the subject,
the camera can make color balance errors by trying to balance light
whose color is not really balanced due to inclusion of the subject. You
do need to balance each shot as long as the light is varying but there
are better ways to do that. But even better is to control the light so
that the exposure and color are always the same.
The first thing I'm going to suggest is that you use an external flash
(or possibly even two) and with the flash provided with lots of
diffusion. You can use a commercial light tent or a simple cardboard
backdrop or a box lined with gray or black paper or cloth. Or even
another color of your choice as long as it's a fairly matte surface.
For diffusion there are many options. A simple and large diffuser would
be to fire the flashes through a white bed sheet suspended in some way
above your target. Or you could use shoot-through umbrellas or, you
name it.
Next get the white balance correct for the light you're shooting in be
it flash or otherwise. I would have called this "setting a custom white
balance" but Olympus uses this term to mean dialing is a set color
temperature. On page 90 of the E-500 manual you'll find Olympus'
version which they call "Setting the one-touch white balance". Best is
to use a good white balance target but, as they suggest, you can use a
white sheet of paper or even your homemade 18% gray sheet if the white
paper is too bright under the light of the flashes. But I'd first cut
back the power of the flashes if necessary. In any case use the flashes
at the planned exposure level for actual shooting. Your white paper or
18% gray target won't likely be truly even in the RGB channels but
probably close enough.
I do have a copy of some version of Paint Shop Pro but I'm not very
familiar with using it. But as I look at the processed versions of your
shots they strike me as over-sharpened. Whether it's the sharpening
alone or something in the camera and/or PSP settings, the contrast is
being raised too high which is what's causing the darkening to near
black in the shell casing. Sharpening works by increasing the local
contrast at what are perceived to be edges. You'll have to work out
what in your process is causing the problem. I think the sharpening can
be dialed back somewhat and perhaps that will be sufficient. If not,
the image does respond well to a simple contrast reduction or perhaps
you'd like to go further and increase the brightness of the "shadow"
areas after the other processing.
In any case, once you have a consistent flash exposure which will allow
a consistent and correct color balance the images should all respond the
same way to further sharpening and contrast control.
If I've not made something clear just ask.
Chuck Norcutt
On 9/27/2010 7:06 AM, Olaf Greve wrote:
> Hi all,
>
> For some research work in the line of Japanese ordnance, I'm currently
> taking pictures of my collection. I use a combination of the regular
> lens-kit lens (from the top of my head that is the 14-45 F3.5-F5.6)
> whenever the object is big enough, and a manually focussed OM Zuiko
> 50/3.5 macro for the small stuff.
>
> Back in the film days, for this I had printed some A3 sized papers
> with an 18% grey tone, so as to be able to take a spot reading on that
> grey background, focus the object in question and then take the picture.
>
> Now, with this digital stuff I have come across some issues with all
> of this, and I would like to know what the best way is to get good
> pictures.
>
> What I have learnt already, is that the WB setting doesn't always work
> as expected. A while ago I had an eye-opener as to just how the 'Auto'
> setting is interpreted. Ever since, tweaks have been made, and results
> have improved dramatically, yet, I think they could be better still.
>
> Here's what I do, and where I have doubts:
>
> As the objects in question (i.e. mainly shell casings and projectiles)
> are often made of (shiny) brass, I do not use a flash. Instead, I take
> pictures outside, on an overcast day, without a flash.
> I have my camera (E-500) forced to not use the flash, and the WB is
> set to the 'cloud' icon (6000K, I think), which I guess means
> 'overcast day'. The picture quality is set to the highest JPEG quality
> (i.e. not the 'raw' format). As a backdrop (and here I think the main
> difference between film and digital may be rearing it's head!), I use
> the same A3 18% grey papers. With AF lenses, I just directly focus on
> the object in question and take the light reading averaged metered
> (with the pattern that measures all over the place), as I find spot
> readings don't work easily with the AF mode. I post-process the lot
> using Corel Paint Shop Pro X2. The actions I almost always take are
> first the "one step photo fix" (which most often tends to give a
> better colour balance, but sometimes seems to be off), followd by an
> "unsharp mask". For most of the pictures (say 90-05%), this gives very
> pleasing, tack sharp (sometimes overly sharp) results. However, on
> some shots the colour seems to be off. For some reason some of the
> shiniest brass casings tend to turn really darkish (black, almost)
> particularly after the "one step photo fix" edit.
>
> My theory is that either perhaps in digital cameras, the averaged
> reading throws colours off, or that the backdrop used should be (full)
> white, instead of grey (at least, if the WB is set to overcast, it may
> interpret the 18% grey as white, hence throwing the colours off)....
> But then, these are just my theories....
>
> I have uploaded some examples of this phenomenon, and I hope someone
> can look at them and give me some suggestions for improving my
> strategy, such, that I can do so without manually having to tweak
> levels per picture, and such that I don't have to use the 'raw'
> format. The reasons for the desired speedy process are purely time
> based: lots of stuff to photograph, and little spare time, so I need
> to be able to do it almost at bulk speeds and hence a few quick
> digital processing steps are all I'd like to do on the pictures...
>
> The pictures in question (full size, so as to not mingle them any
> further by down-sizing them):
> 1: http://www.millennics.com/test/1_raw.jpg : casing 1, as it came out
> of the camera (no edits)
> 2: http://www.millennics.com/test/1_edit.jpg : casing 1, "one step
> photo fix", "unsharp mask", "cropped", exported with "JPEG optimiser",
> compression set to 15%.
> 3: http://www.millennics.com/test/2_raw.jpg : casing 2, as it came out
> of the camera (no edits)
> 4: http://www.millennics.com/test/2_edit.jpg : casing 2, "one step
> photo fix", "unsharp mask", "cropped", exported with "JPEG optimiser",
> compression set to 15%.
>
> In both cases you will see that the end results are far more pleasing
> than the unedited version, in terms of sharpness, but also, in both
> cases a considerable darkening can be seen. Particularly the bottom
> part of casing 1 has gone much darker, blackish almost....
>
> Are these about the best results achievable, or can anyone give me
> some pointers for improvement?
>
> Thanks in advance, and cheers!
> Olafo
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