With the transition from analog to digital photography for consumers, also mineral photography was pushed into a new dimension for several reasons: film cost disappeared, so experimenting was no more expensive and the result was immediately visible. Also new techniques like layer compositing opened a door to micro photography in before unknown quality as the depth of field barrier was pushed away.

The Drilling Stand Setup

For the author, mineral photographer since 1971, digital photography was a new beginning, after waiting some years for affordable and convenient digital cameras. The first camera I used was a Nikon Coolpix 950 for its macro capabilities and its relatively easy adaption to a microscope.
It took some months and the camera was adapted on a bellows with Zeiss Luminars and other macro lenses. The first setup was realized with a drilling stand, an idea I copied from my friend Klaus Petitjean. The configuration and first results have been published in 2005. (Betz, 2005)

The instrumentation at that time had several weak points: The stand had only one position to mount equipment and the use of two additional lenses ( camera lens and ocular-lens) was an unwanted tribute to the available cameras. Also the stacking distance was limited, less than 50 µm was difficult and the manual stacking was time consuming.

Cameras improved and the Nikon Coolpix 950 was replaced by a Coolpix 4500 with more pixels and higher resolution.

The Leitz Ortholux I period

In order to photograph smaller object, which need smaller stacking distances microscopes bodies subsequently have been used. The object table of good microscopes allow adjustment with a resolution of 1 µm. But this improvement has to be paid with two disadvantages: the travel distance of the fine drive is only 2 mm and the working space between the microscope lens and the object table is to small to use lenses of greater than 40 mm focal length, so field of view was limited to ~5 mm with this setup.

Around 2007 features and price of DSLR came in a range to be considered for mineral photography work. The author, a Nikon user for long time, was the disappointed by the features of the first low cost Nikon DSLR, as the analog Nikon lenses in stock would not fit and a manual mode (M) with a manual lens was not supported. But a Canon 350 D did the job with a cheap adapter. So all equipment, bellows, tubes and lenses from Nikon could be used with a Canon body. But soon it was clear the the use of a DSLR had also limitations. The mirror and the mechanical curtain of the shutter caused vibration resulting in loss of sharpness. So the ideal camera would be one with no mirror and no mechanical shutter. Mirror lookup was a first improvement with the Canon 400 D and the with a Panasonic G2, a mirror less DSLM camera was marketed and tested with improved results following an hint of Stephan Wolfsried.

Documentation Photography

In order to photograph all sizes mineral specimens for a period of time I used three setups as shown below.

For 20 mm field of view and larger a Canon DSLR with macro lens and the range between 20 mm to about 3 mm with the existing drilling stand and bellows. For all smaller Fields of view the Leitz Ortholux I was used.

Life View and Remote Control via USB

A further step of improvement was life view modus, now the mirror was always up during life view so no more disturbing and (with Canon DSLR) it was possible to take pictures with a first electronic curtain and a second mechanical curtain after exposure, with little impact on sharpness.

For the way back to Canon DSLR after using a Panasonic D2 mainly the remote software of Canon for Windows and the remote control of Canon (and Nikon) cameras with the Helicon Remote software via USB was the primary reason. Coming WLAN connection hopeful will improve this.

Automation of Stacking

With Macro Lens

Until this point all stacking was done manually. The first automation step was done with a Canon Macro Lens EFS 60 mm 1:2,8. With life view and remote control via Helicon Remote the camera can be controlled by the computer and also the pictures go direct on the PC hard disk. Only positioning of the specimen and lightning is done on the photographic setup. Experiments showed that all mineral pictures taken, benefit from focus stacking. Macro lenses typical have their best resolution at an aperture of 8 and from now on stacking a few pictures was done for most pictures.





The camera preview is much better ttan the small sceen at the camera.

With StackShot

The second step of automation came with StackShot. Primary designed as a stepper motorized camera carrier for macro work it can be used also as specimen carrier. If size and weight of photographic equipment are compared with thumbnail and micromount specimens it is apparent that specimens are more easy to move. So my decision was to use StackShot as specimen carrier.

To fit all parts together a convenient and rugged stand was needed. A solution was found in the use of custom cut aluminum profile parts and corresponding connectors. Both, camera and StackShot are assembled on a 50 cm long 45x90 mm aluminum profile which is mounted on a 20 x 36 cm aluminum profile base plate. The stackshot can be easy fitted with two 3/8 “ UNC screws. Mounting the photographic equipment was more difficult, but was also made with two aluminum profile parts and some screws. The position of both StackShot and camera setup can easy adjusted in the proper distance. All focus adjustments in Z- direction are made the with the StackShot. For the X/Y adjustment of the specimen position on the platform of the StackShot a X/Y micrometer stage is mounted. This is also used for size measurements. With this kind of equipment now stacking is no more stressing. While 50 or more stacks are taken the photographer can relax.

Mineral Videos

With the use of a Canon 650 D also HD-Video clip capabilities popped up. And indeed, videos are an interesting alternative to still pictures for mineral specimens if high resolution is used while the small youtube format is rather frustrating, because much details are lost. But videos need movement, so either the camera or the specimen or both have to move. Smooth and slow and without disturbance for the eye of the viewer. With the before acquired experience, using aluminum profile parts, a versatile stand for macro photo and macro video was assembled, which is shown below. Movement of the camera was integrated by adding a camera trolley on a stand which can be used in various ways.
Tilt and rotation features could be added by converting a motorized camera tilt and rotary head to a remote cable controlled specimen carrier platform. Only videos cannot be shown at Mindat at present. Possible fields of views are from 10 mm to about 10 cm. The lower limits are given by optics and depth of focus and the upper limits by the size of the platform. Needless to mention that such equipment is also an excellent device for still photos including stacking. The specimen platforms are easy to exchange and a large glass plate table can be used.




(A HD-video (??) may be here in future)

Further Projects

While the StackShot uses a acme screw thread, which allows large traveling distances, but limits the smallest steps to a few micrometers, motorizing a micrometer translation stage would make much smaller steps possible. The Helicon Remote software allows to control a specific stepper motor ( Trinamic) which can be used to drive a micrometer translation stage stage as well es other equipment. This has been tested and steps in the 0.5 µm range are possible for a traveling distance of 2 cm. This is only of practical use if corresponding lenses with high resolution and large aperture are used.

The above mentioned tilt and rotation table is manually controlled by a cable and joystick and uses two DC motors. To control that and the camera trolley via USB from the computer is a future project.

To be continued....