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Focus stackung without a stacking rail using a lens combination

Last Updated: 9th Oct 2016

By Volker Betz

In digital mineral photography, macro lenses with 50 to 100 mm focal length, give excellent results down to about 22 mm field of view (1:1). This kind of lenses can be used in live-view for focus stacking with f= 5.6-8, if the camera is compatible to stacking software like Helicon control or DigiCamControl. This saves the extra cost of a stacking unit like Stackshot or StackMaster.

The close up range of such macro lenses can easy extended to a 2:1 range by adding a Raynox M250 lens to the front of the macro lens, resulting in an 11 mm field of view with an APSC body.

Further extending is a little bit more difficult and possibly limited to digital macro lenses of 100 mm and more. Reasonable results could be obtained by adding a (analog) Nikkor 24 mm 1:2.8 in reverse mount to the front of a Canon Macro Lens EF 100 mm 1:2.8 by means of a retro ring and filter adapters.

The lens combination:
Lens combination of a Canon Macro Lens EF 100 mm 1:2.8 USM with a Nikkor 24 mm 1:2.8 revese monted on the front of the Canon Lens. Camera monted on e experimental rack with x,z camera slider


This lens combination has a field of view of about 5 mm (~4:1) with reasonable results. Both lenses have been used with open aperture. Closing the aperture of the rear 100 mm lens causes shadowing in the edges of the picture. Under remote control the focus motor of the 100 mm (rear) lens allows focus stacking over more than 3.5 mm. Focus stacking over that distance needs 250+ focus steps of the focus motor of the 100 mm lens and is slow. A stack of 25 to 30 pictures gives reasonable results with Method B and C of Helicon Focus.Field of view and resolution have been tested with a millimeter paper and an object micrometer.From the object micrometer a resolution of less than 2 µm can be estimated.


Field of view and resolution:


Millineter paper, single frame. (Enlarge pictures for details)
Object micrometer, single frame
Detail of object micrometer, single frame at 1.6 mm FOV
Millineter paper, single frame. (Enlarge pictures for details)
Object micrometer, single frame
Detail of object micrometer, single frame at 1.6 mm FOV
Millineter paper, single frame. (Enlarge pictures for details)
Object micrometer, single frame
Detail of object micrometer, single frame at 1.6 mm FOV


Example Picture Haüyne
Haüyne crystal photographed with a lens combination of a Canon Macro Lens EF 100 mm 1:2.8 und a Nikkor 24 mm 1.2.8 mounted reverse on the front lens of the Canon lens. Focus stacking of 26 frames was made with the focus motor of the Canon Lens.
Conclusion: Focus stacking with the focus motor of digital macro lenses can be extended to 4:1 scale with reasonable results, saving the extra cost of a stacking rail. This is useful if only occasional that range is needed. Pictures made with rail stacking and a special lens like a 40 mm Luminar or a 5x infinitive Plan Apo Lens with a tube lens on bellows bellows are typical better.






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