Dear Karwan,

I can imagine what you mean if you want to take pictures of a polished rock surface to produce sharp images contours. In my experience, the use of any type of color filtering is not advisable as the natural colors are changed significantly. The blurry overall impression is created by the fact that the incident light entering through the polished surface to the depth of the rock sample. The resulting scattered light causes the general blurring of the image. The same effect of light scattering occurs when the ground surface is wetted with water.

Unfortunately, I see no way out of this dilemma with the exception that a polarizing filter can reduce the scattered light, and thus the focus can be improved somewhat .

Best regards,

Guenter

Dear Guenter,

Thanks for your answer and you information are interesting to know. I tried with water wet surface but still not happy with the results. When I take photos and zoom in then its blur and the detail sometime is obscured. 

Thank you very much.

Regards,

Karwan

Dear Karwan,

I use always a simple scanning device with high resolution for the documentation of polished rock surfaces - see examples below.....

best regards

Andreas

Dear Andreas,

Thank you very much, I have been using such technique but I think I will miss some details with this method. When I zoom to see details, I will miss some. 

Your idea is very well known and is so far generally the best . 

Regards,

Karwan

Dear Adnreas,

I'm wondering whether what properties of scanning are you using for such nice photos? I always go for 600 dpi and Pdf format. 

If you please give me some information, then I can try with my rocks. Thanks for your answer.

Best regards, 

Karwan

Dear Karwan,

I use in correlation to the size of the sample normally between 800 and 1200 dpi and save them in tif format. For the documentation of small details (e.g. 2x2 cm) I use 2400 - 3600 dpi and tif format too...in most cases the results are even better than a picture through the microscope...;))

The pictures which I uploaded yesterday, of course do not have such a high resolution and the format ist jpeg, therefore many details got lost.  In the separate storage of my PC all these pictures are saved in high quality resolution - with the disadvantage of the large datasize from about 240 MB for each picture..........

best regards

Andreas

Scanning is a reliable method for documenting a flat surface as Andreas notes, and clearly he has experience in that practice worth following. My work involves photographing artworks; layers of translucent, transparent or semi-transparent oil paint in varnished paintings I would think present similar problems. You may be dealing with minerals that can be seen beyond the planar surface, and the reflectivity of the polished surface is obscuring them. A single, point-source illumination, projected 45° across the surface may reveal more than the broad beam of the moving scanner light source. If you add polarisation to the point-source light (a flash unit for example, or incandescent lamp, or LED) and the cross-polarise the lens, you will remove reflection from the surface and intensify and saturate the coloration of the specimen. If it is crystalline, the crystals, which have their own polarising effect, may generate distinctive prismatic colour in reaction to the incoming polarised light. A demonstration may be found at 

http://archaeologydataservice.ac.uk/archives/view/stones_ahrb_2005/cfm/Public/details/RockDetails.cfm?RockCode=PURGRN&BCnt=1&Choice=2