Difficult to Photograph Minerals - Tips/Strategies for Success
27th Mar 2014 02:13 UTCAnonymous User
Try illuminating only with light reflected off matt white surfaces? Or try something else? Immersion photography can kill surface reflections The RI of the immersion fluid need not match the RI of the subject crystal but the close you get to a match the easier it is to get a good result. But water is cheap and often works well enough. A third technique is to use polarising filters on your lighting; this has variable results but is worth trying - see below. A fourth method is to retouch the image by hand, post-processing it with PhotoShop etc.
Here's a macro shot of 7ct faceted spinel imaged between crossed polars to kill all reflections from the polished facets. A second effect of the polarisation with *this* specimen is to show the strain set up in the some of the inclusions within the host specimen.
Here's an image (made by a MINDAT friend, using a point-and-shoot camera and a single bedside light with a diffused tungsten bulb.This suffers from the same problem as in your shot I think. Here's a copy of the original image before re-touching to remove the 'white dust, before proceeding to some cropping etc.
Hope this helps.
Here's a macro shot of 7ct faceted spinel imaged between crossed polars to kill all reflections from the polished facets. A second effect of the polarisation with *this* specimen is to show the strain set up in the some of the inclusions within the host specimen.
Here's an image (made by a MINDAT friend, using a point-and-shoot camera and a single bedside light with a diffused tungsten bulb.This suffers from the same problem as in your shot I think. Here's a copy of the original image before re-touching to remove the 'white dust, before proceeding to some cropping etc.
Hope this helps.
Nice specimens, David - and nice shots too. I particularly like your fluorite and the flash shot in particular. It satisfies.
DOF control is as old a concern as optics. My view is that where one can exploit the effect to one's advantage, one should. Where one can't - and there are occasions when one really can't - then reach for the image stacking software.
Here's an example of where one can't get what one wants except by making DOF limitations work for one - and leaving the stacking software alone. Subject is a part of a hydrothermally grown quartz crystal appox 90x20x13mm, grown on a seed plate. In this first macro shot through the 13mm dimension, image stacking was used; the aim being (1) to image the seed plate and (2) to capture the unusual growth structure on one face of the crystal (the far face from the camera) that is never found in naturally formed quartz, or so I believe. To show up any strain in the crystal. this macro shot below has taken in air between the crossed polars of an Eickhorst M2 polariscope. The lighting is the fluorescent tube of the M2; this is of a modern design and has a colour rendering index of 90. Viewed in unpolarised light, the quartz is absolutely colourless.
The resulting stacked shot is a nice shot of the growth pattern on the far side but this is so 'busy' that one has to search for signs of the seed plate about halfway down the crystal and the eye does not register its features readily.
So a second shot, unstacked, and using the DOF limitation to eliminate all the clutter and isolate the seed plate from the background. The magnification looks a little higher but that has been achieved simply by cropping the image a little tighter, the purpose being to make the two phase inclusions in the seed plate just visible :-) I must have another go at those some time under the microscope.
Re. that spinel shot. That too was done in air using the M2 polariscope and its lighting and not with the stone in immersion.
With regard to your comment that the quality (colour rendering) of day light is not as controllable as are good artifical lights of certified performance, I agree. However, do try a North light (sky only) and best of all on a cloudy day. The uniformity of this in terms of colour temperature and hence the effect on light coming to the eye from a subject of interest, is what daylight - especially direct sunlight - from any other direction lacks. It's particular benefits were discovered by medieval painters and it is still widely used even today for the making and appreciation of visual images. Of course, this is only true for those living in the northern hemisphere. In the southern hemisphere, use a South light.
DOF control is as old a concern as optics. My view is that where one can exploit the effect to one's advantage, one should. Where one can't - and there are occasions when one really can't - then reach for the image stacking software.
Here's an example of where one can't get what one wants except by making DOF limitations work for one - and leaving the stacking software alone. Subject is a part of a hydrothermally grown quartz crystal appox 90x20x13mm, grown on a seed plate. In this first macro shot through the 13mm dimension, image stacking was used; the aim being (1) to image the seed plate and (2) to capture the unusual growth structure on one face of the crystal (the far face from the camera) that is never found in naturally formed quartz, or so I believe. To show up any strain in the crystal. this macro shot below has taken in air between the crossed polars of an Eickhorst M2 polariscope. The lighting is the fluorescent tube of the M2; this is of a modern design and has a colour rendering index of 90. Viewed in unpolarised light, the quartz is absolutely colourless.
The resulting stacked shot is a nice shot of the growth pattern on the far side but this is so 'busy' that one has to search for signs of the seed plate about halfway down the crystal and the eye does not register its features readily.
So a second shot, unstacked, and using the DOF limitation to eliminate all the clutter and isolate the seed plate from the background. The magnification looks a little higher but that has been achieved simply by cropping the image a little tighter, the purpose being to make the two phase inclusions in the seed plate just visible :-) I must have another go at those some time under the microscope.
Re. that spinel shot. That too was done in air using the M2 polariscope and its lighting and not with the stone in immersion.
With regard to your comment that the quality (colour rendering) of day light is not as controllable as are good artifical lights of certified performance, I agree. However, do try a North light (sky only) and best of all on a cloudy day. The uniformity of this in terms of colour temperature and hence the effect on light coming to the eye from a subject of interest, is what daylight - especially direct sunlight - from any other direction lacks. It's particular benefits were discovered by medieval painters and it is still widely used even today for the making and appreciation of visual images. Of course, this is only true for those living in the northern hemisphere. In the southern hemisphere, use a South light.
