[Rockhounds] achieving depth of field w digicam?

[Rik Dillen]

Hi Axel (& others, of course),

In fact Axel knows already my opinion.
My point of (unstacked) view is not opposite, but quite different from Axel's (which does not mean that we aren't good
friends :>).

I have no objection against stacking software, and for me it is not even necessary to mention the used technique.
Here are my arguments :

1.	When we look at a specimen and we need a depth of view, we move, turn etc. the specimen, and our brain/memory
makes a stack of the images, creating in that way a more or less 3-D view of the specimen. Stacking software does
(about) the same thing on a photo.
2.	When we take an analogous photo (meaning : with a classical camera, on film) we narrow artificially the
aperture, and use a much higher exposure time to obtain a higher depth of focus (taking into account Axel's arguments in
his second message). Stacking software pursues the same goal, using different means.
3.	Imagine that you would be able to have a heterogeneous lens, meaning that the focal distance would change
gradually from the centre towards the edge of the lens, than you would be able to make a photo where a crystal in the
centre would be sharp in focus, and the background material towards the edges of the lens as well, because the focal
distance would be adapted. Of course, such a lens would have to be designed just to take one photo :>)  Such a photo
would not be considered as "not permissible"... however the only difference would be that other means have been used for
(something like) the same result as if you follow the way of stacking software.
4.	The depth of focus of our eyes is far better than that of a camera. This means that a photo (not stacked) does
show in fact even less than your eyes would see directly. In fact the depth of focus of human eyes is perhaps not "far
better", but the brains combine the images of both eyes... in fact what we see is a "stack" of two images... a photo
shows only one image instead of a combination of two.
5.	Any photographer would have no objection to a photographic panoramic view. Again, this is an example of
something that we would not be able to see with our eyes. Also that is a case of stacked photos, but instead of stacking
them in a sophisticated way by software, they are combined one aside of the other, and the edges merged in the darkroom
(or digitally).
6.	The purpose of a photo has, IMHO, always some didactical purpose, and therefore, the more detailed information
one can show clearly in one photo, the better. Even if that necessitates the use of stacking software. On the condition,
however, that nothing is shown that wasn't there in reality. Then it would become fake.
7.	Perhaps the most important of my arguments is that a stacked composition of photos shows nothing that was not
really present, therefore for me nothing is wrong with such type of imaging.

And I admit that there is, as always, some sort of a gray zone : what about the correction of a wrongly tuned color
temperature ? What about enhancing sharpness, contrast etc ? What about the use of a "soft focus" lens, that reduces
sharpness artificially ? Those things are done digitally, but were done as well in the dark room in the last century.
Also in analogous photography many techniques produce images that are not exactly as the naked eye would see.

On the other hand I want to emphasize on the fact that I don't even have any stacking software, and so far I did never
use it. Since the time I have a decent digital camera I did not have the time to do much about photography of minerals.
So I am not defending "my technique".
I hope to get to mineral photography as soon as I will retire (that is 1 July 2010).

And of course, this is just my opinion and interpretation of things, not the absolute truth. I think that this
discussion is fruitful as such, and everyone has to distill his own conclusions from it.

Best regards,

Rik DILLEN 
Doornstraat 15,  B-9170 Sint-Gillis-Waas 
Belgium 
E-mail rik.dillen at skynet.be 
Homepage : http://users.skynet.be/rik.dillen 
 
MINERANT 2008  -  26-27 April 2008
Bouwcentrum (Antwerp Expo)
Jan Van Rijswijcklaan 191 Antwerpen 
http://www.minerant.org/mka/minerantnl.html 
Mineral collector's page http://www.minerant.org/ 

-----Original Message-----
From: rockhounds-bounces at lists.drizzle.com [mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Axel Emmermann
Sent: Wednesday, April 16, 2008 8:34 PM
To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
Subject: RE: [Rockhounds] achieving depth of field w digicam?

Tim,

The problem is real but exists mainly in our minds.
A photo is a flat object thus our mind expects it to be in focus all over
when we look at it.
Nonetheless, if the photo is a macroscopy of something that is 1 cm wide and
has 1 cm of depth, than it would NOT be a good reproduction of reality if it
were ALL in focus.
Take out the fossil and look at it with just a loupe or even the naked
eye... There is no way that you can get view that is "sharp" all over "at
once". You focus on one point at a time and that point is in focus along
with all the other points at equal distances from your eye.
If you want to reproduce reality, you should be prepared to make sacrifices.
Making background and foreground out of focus while providing a solid focus
on the subject firmly "places" the subject in the reality that you want to
show the viewer.
Look at my photo:
http://www.flickr.com/photos/22753159@N04/2212174499/in/set-7215760378477153
7/ (you may have to unwrap) 
Or
http://www.flickr.com/photos/22753159@N04/2212174565/in/set-7215760370425562
9/
Both photos show distinct gradients in sharpness.
These out of focus zones assist the viewer's mind in designating an
hierarchy of depth-levels...to place the object in space, relative to the
other objects in the picture that are either in or out of focus.

If you "stack" images to obtain overall sharpness, you forfeit the reference
points that allows the viewers to "spatialise" the object in their minds.
In some rare instances you may want to let the didactic aspect prevail.
Sometimes you just have to show the full detail for the sake of science...
Say an insect included in amber or for that matter, any inclusion in any
transparent mineral.
I think that the use of stacking software for such purpose could very well
be deemed permissible.
However, I'm a fervent advocate of integrity in all aspects of life... I
guess you can hear me coming ;-)) Each and every photo that is a result of
stacking software or HDR tools should be labeled as such. (yes, period). The
author of the photo should volunteer the information upon publication in any
form without the viewer having to inquire about it.

There you have it, my two Eurocents ;-)))

Axel