Transverse section of fossilised beech wood ~16MYA

Bruce Williams · Post by **Bruce Williams** » Fri Mar 30, 2007 3:25 pm

Hi folks,

A section of fossilised wood from the Rattlesnake Hills located in the east of Washington State. The image covers an area of 9cm X 6.75cm.

[EDIT] Latest research strongly suggests Mid-Miocene (~16 MYA). Subject title changed to reflect.

I took this pic mainly to provide a frame of reference for my posting in the Microscope Forum, showing detailed structure of microscopic pore structures. Please do check it out for some information on the fossil and of course the microscope images.

Ok this pic. Boy was it a headache to take - mainly due to the extreme contrast of the light and dark areas but also because focus had to be spot on to show growth ring detail etc. Anyway I ended up taking several at slightly different focus and with a range of +1EV to minus 1.5EV in 1/3 EV steps. I then manually merged the best light with the best dark shots.

After all that it's still not a patch on the real thing which has a gem-like shine to it and shows much more detail to the naked eye - and a wealth of detail with a 4X watchmaker's loupe. BTW, it's not covered in dust - the spots are just tiny flaws in the silicate (chalcedony).

Bruce

beetleman · Post by **beetleman** » Fri Mar 30, 2007 4:22 pm

I think you did a heck of a job on a really tough object Bruce. I love when these fossils have the bark intact. An actual slice of pre-history. Heading on over to micro now...........

MacroLuv · Post by **MacroLuv** » Sat Mar 31, 2007 8:04 am

Very nice!

This one looks like it was pulled out from the fire.

One more interesting thing. Photo properties says 480 x 720 pixels which is less then (for example) my Kalanchoe photo 800 × 533 but occupies more space on the screen

Bruce Williams · Post by **Bruce Williams** » Sat Mar 31, 2007 9:22 am

Thanks Doug

Nikola - I was sorely tempted to keep you guessing on this one but...

You are looking at two separate, seamlessly joined 480 X 720 frames which together give the effect of a single image. At the maximum 800 X 600 size, the annual rings and medular rays were all but invisible, so I decided to upsize to 960 X 720 which required the use of 2 images to stay within Forum rules. I have to thank Rik for advising on the possibility and for providing the "how to" information (the html code for the second frame must start immediately after the [/URL] of the first frame).

FYI - The black/brown colour was not caused by fire but by the presence of manganese oxides and iron oxides during the long period of fossilisation.

Bruce

MacroLuv · Post by **MacroLuv** » Sat Mar 31, 2007 9:58 am

You have joined it horizontally and got me fooled.

I don't know why I expected vertical join? The preconceptions are very screwy things.

I should figure it out from horizontal 480 < vertical 720.

I was already shaky by work software problems. Almost lost or change my faith and start to belive in "ghosts".

P.S.
If dating corrections will keep this speed (reduced by 78.67% !) it could be a split log from the last winter!

(just kidding)

DaveW · Post by **DaveW** » Sat Mar 31, 2007 10:44 am

Your lighting looks fairly diffuse anyway Bruce, so how did you light it? I ask as you can often cut contrast by using a diffuser between the light source and subject as that will often bring both light and dark parts within the exposure range of the sensor, but you may have already tried this?

DaveW

Bruce Williams · Post by **Bruce Williams** » Sat Mar 31, 2007 1:03 pm

Hi Dave,

I used a light tent placed on its back with the camera looking down into it. Illumination was by 2 X 50W halogen lamps located outside of the tent to left and right (lights directed on material at about 15" from base). So lighting was entirely diffuse - no direct lighting at all. I did try direct lighting and a combo of direct and diffuse (just to check) but as you would anticipate, results were far worse.

The posted image is fairly true to life but somehow the real thing is more vibrant and shows more detail in the black areas. If I overexpose (or play with levels in CS2) to bring out the darker detail, the black starts to look grey which is then not true to life.

Thanks for your interest - much appreciated

.

Bruce

DaveW · Post by **DaveW** » Sat Mar 31, 2007 1:27 pm

As usual our eyes have a greater range than any digital or film camera!

DaveW

rjlittlefield · Post by **rjlittlefield** » Sat Mar 31, 2007 9:35 pm

I'd guess that a DSLR shooting "raw" has enough dynamic range to capture this subject pretty well. The challenge is getting all that range into an image that can be jpeg'd and then displayed on a monitor.

Uncomfortably large dynamic range is a common problem in the panorama community. That's not to say that it's perfectly solved! But some useful tools and techniques are available. If you want to investigate, the magic words are tonemapping and HDR (High Dynamic Range). See for example at http://wiki.panotools.org/HDR.

--Rik

Bruce Williams · Post by **Bruce Williams** » Sun Apr 01, 2007 6:11 am

Thanks for the link Rik - I will check it out thoroughly.

So far I have not made use of CS2's HDR function or other third party *software but (as I did with this image) have chosen to manually merge 2 or 3 shots taken at different EV settings. In this instance I merged shots of +0.7EV (darkest areas), +0.3EV (main body) and -1.0EV (bark).

My Minolta A2 does take RAW and I guess I really should experiment more with it - particularly with these (not uncommon) subjects having large dynamic range.

*I think it was you that recommended I take a look at Photomatix? I did a thorough check of their website and downloaded their trial version, but as yet I haven't really checked it out .

Thanks

,
Bruce

rjlittlefield · Post by **rjlittlefield** » Sun Apr 01, 2007 10:21 am

Bruce Williams wrote:I think it was you that recommended I take a look at Photomatix?

Not me. I have never used Photomatix or any other similar automatic tool. All of my HDR-type work has been done with manual masking of multiple exposures, either shot as separate images or recovered from a single raw image by adjustment of the conversion parameters.

I have not had time to explore HDR & tonemapping nearly as much as I'd like. I will be eager to hear what you come up with!

--Rik

PS. With my Canon 300D, it turns out that there's a huge difference in shadow quality between shooting JPEG in the camera, and shooting raw in the camera and generating the JPEG in Photoshop, even using default parameters everywhere and ending up with the same size JPEG file. The camera's raw conversion and jpeg compression gives streaking and color artifacts in deep shadows, where the same areas come out clean in Photoshop. The difference is subtle if I just put two images on the monitor, but if I do a level adjustment to pull up the shadows, it becomes blatantly obvious. Yet another of the reasons why I always try to shoot raw if feasible.