Stackshot

[Pete Askew]

Today I decided I needed to get to grips with a bit of kit I bought a while back for work. And, to make it a bit more interesting I used the skull of a Magpie as the subject! Here is the final, test image.

It is a composite made by focus stacking 50 images taken at 50 focal points, each 1 mm apart. Now, as you can imagine, this is a tedious business when done by hand, and prone to quite a bit of error. However, it can be automated and in this case the automation was achieved using a piece of equipment from the company Cognisys called a Stackshot. It is comprised of a camera support on a guide rail driven by a stepper motor connected to a controller that automates shoot / move sequences. Here is the setup:

You can see the Stackshot mounted on the Devere copy stand and on it is mounted a Nikon D3s + 55mm Micro Nikkor (I also have an interface cable to allow connection to our D800 / D800E). The skull is sitting on the black background and is angled up towards the camera). Image stacking was performed using Helicon Focus although the unit can interface with Zyrene Stacker as well. After stacking, the composite image was imported into LR for cropping and minor adjustment (cleaning up of specks on the background and the removal of the odd artefact etc).

Details of the unit can be found at:

https://www.cognisys-inc.com/products/stackshot/stackshot.php


I also have a second stepper motor that can be controlled by the unit and the idea is to interface that with the focus control of a microscope to allow more accurate stacking of micrographs.

 

[Rob MacKillop]

Well, the resultant image is beautifully clean and clear, so it seems worth the effort, in my opinion. Very interesting. What use will you put it to at work?

 

[Julian de'Courcy]

First I'll say good morning Mr Magpie .
That is trully a good bit of kit Pete and interesting to see. I've tried focus stacking using Cs6 and Helicon, I did not find it enjoyable, very tedious and often with faults, especially in Cs6. Yet on the occasions it got close the results are worth while as I see here.

 

[Pete Askew]

Thanks, both.

The problem with macro-photography is the narrow depth of field. When you want to show something lik mould growth on a complex structure (rather than a flat panel) it can be quite difficult to relay what can be seen by the naked eye into an image in a report. Stacking can help. However, my main interest is to try and get this to work on a microscope as the DoF is much, much narrower and you cannot focus up and down on a page!

 

[Rob MacKillop]

Fox Talbot would be impressed, as I was with his vision of the varied uses photography could be put to. He seemed to understand the potential for photography to be more than landscape and portraiture. His work on ferns at my local botanic gardens is impressive. He also promoted photography as being useful for archival work. And he also created the first deliberate "art" photograph, with his broom at "The Open Door".

You're a modern-day Talbot, Pete. Or at least a Fox!

 

[Ivar Dahl-Larsen]

Wonderfully done, now that I know the rest.

 

[Pete Askew]

Thanks, Ivar. Mainly down to the software though.

 

[Brian Moore]

That is not a magpie. That is @Dan Cattermole. And a bonnie fotie of him so it is! (Although, I was not hitherto aware of the diminutive dimensions of his cranium, Pete. This is photographic reportage at its best! )

 

[Pete Askew]

Thanks, Brian.