Equipment TestLast Updated: 12th Feb 2014
By Volker Betz
Test of a Setup for Automated Multifocus Processing using Bellows and Microscope Lenses
The author started to use multifocus processing for mineral photography almost 10 years ago. It was the beginning of a new era of photographing micro minerals. Since these early days many improvements happened with the digital cameras and the stacking software packages inclusive automation with motorized devices for focus control.
To use the technical improvements a new device was assembled shown in the picture below.
It consists of a home made stand made of a 45x90x500 mm aluminum profile, mounted on a 340x200 mm aluminum profile plate. All photography parts are mounted on the vertical stand.
From top to down mounted are :
1.Canon 450 D camera with remote control via USB and Live View (with Helicon Remote)
2.Novoflex bellows adapted to Canon EOS mount at camera side and a conical RMS adapter to mount Macro lenses for RMS (W 0,8" × 1/36" ) mount.
3.Different macro lenses and microscope lenses from 15 to 63 mm focal length.
4.Stackshot rail with specimen carrier and two linear stages for size measurement and position adjustment. Stackshot control via USB with Helicon Remote
Mounting of all parts was done with standard screws and bolts, some adapted to 3/8".
Not visible: PC with the following software:
Helicon Pro with Helicon Filter and Helicon Remote, Canon Utilities
Zerene stacker, IrfanView, Adobe Photoshop Elements 10
A system test was performed by photographing an object micrometer of 1 mm length. Beside the well known (and expensive) Macro lenses also 1 X to 10 X reflected light microscope lenses can used if they are marked for use without cover slip. A lens can be used if the lines can be focused and do not show disturbing chromatic aberration. This may not always possible with tube lenghts away from tha marked distance.
Test picture using a aus Jena 10 x A=0,25 160 / - with 250 mm extention (bellows)and Canon 450 D life view and Helicon Remote control. Stackshot set to 10 microsteps. Stack of 30 pictures at 2 steps (20 microsteps) per picture. The scale is a photograph of a object micrometer of 1 mm
A test showed that with the stackshot rail adjusted in the 5 to 10 microstep range automated stacking can be done even with a lens of N/A = 0.25. Such lenses require typical a stack of 30 pictures and more. The LiveView modus of the camera dos not cause significant resolution loss if a sufficient pausing between shots (e.g. 3 sec.) is used.
After several months of successfull testing the system was rebuilt, some mounting parts replaced and a camera and bellows carrier with a bette adjustable design added. Camera and bellows are now easy replaced by a camera T-mount or C-mount tubing alternatively with microscope phtotubus.
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