Focus Stacking with a Raspberry Pi – Experimentation with 10x Microscope Objective

    Cluster fly proboscis
    Cluster fly proboscis

    My Nikon CFI Plan 10x 0.25 ∞/- WD 10.5 infinity microscope objective arrived a few days ago from the USA. I had first seen this lens on Johan J. Ingles-Le Nobel’s excellent Extreme Macro site and had been watching out for one on e-bay for a long time. While it was in transit I acquired on e-bay the necessary adapter rings to enable it to fit onto my Minolta 200 mm lens which is required to deliver the 10x magnification.

    The CFI Plan 10x 0.25 ∞/- is a lovely little lens. The dof, at 8.5 microns, is getting near to the limit of my focus-stacker but I have managed to produce a reasonable test image with it. If push comes to shove I can do a 2 micron focus increment which is one cycle of the stepper motor. The critical factors at this magnification seem to be vibration of the camera even though in my focus stacker system it is stationary; it means tiptoeing round the house while the focus stacker is busy stacking. Dust and contamination on the sensor is the other big issue, which now really shows up in spades. I had done a wet clean of the sensor a few weeks ago but that was the first one for several years and I think the sensor needs one more go at least, as the last clean has not done nearly a good enough job.

    The photograph above is the proboscis of a cluster fly – 197 images at 8 micron increments stacked and re-touched in Zerene Stacker and post-processed in Lightroom, Photoshop and Topaz Detail,  The proboscis is about 0.25 mm in diameter to give you an idea of the scale. The image required a lot of cleaning in Photoshop to remove the worst of the streaks and blobs caused by sensor contamination. None of these streaks and blobs show up in normal photography!

    Over the next few weeks it is my intention to carry out a series of tests with this microscope objective to establish the optimum focus increment and ideal aperture setting for the 200mm lens. I am suspecting that f8, which is what I determined was the optimum aperture for reversed enlarger lenses, may not be the best aperture for the Nikon CFI Plan 10x 0.25 ∞/- and that something wider open may be required. We will see. I will post the results when I have them.


    Focus Stacking with a Raspberry Pi – Focus-Stacker Project Parts List

    I thought it was time that I set down the list of parts that were used to build my focus-stacker. The cost was less than £120. If you live in the USA you could probably do it for the same in dollars – or less!  And it does depend a lot on what you have lying around at home that you can use for this project. I have not included anything to do with lighting or camera equipment other than the IR trigger. Most of the parts were purchased on e-bay with some like the Pi  itself coming from Amazon. You do need to check when purchasing cheap electronic parts on e-bay to make sure they are not coming from Hong Kong if you want them quickly. Shipment from HK  can involve up to a ten week wait for the item to be shipped surface, though sometimes items arrive remarkably quickly. Factor shipment time from HK into you procurement and build schedule if going down that road.

    For the working parts – electronics, motor and rack drive:

    1. Raspberry Pi RBCA000 ARM 1176JZF-S Motherboard 512MB RAM – £ 27.39
    2. 8GB SDHC SD Card pre-loaded with Raspbian “wheezy” Linux operating system – £8.29
    3. iZKA® High Power Micro USB UK Dedicated Mains Power Wall Supply Charger For Raspberry Pi – (5V / 2.1A) – £6.99
    4. 40 wire ribbon cable Male to Female with ends broken out to individual contacts – £4.99
    5. 40 wire ribbon cable Female to Female with ends broken out to individual contacts – £4.99
    6. Arduino 5V 4-Phase Stepper Motor with ULN2003 Control Board – £6.90
    7. SainSmart 2-Channel 5V Relay Module – £8.00
    8. Micsc LEDs, resistors, switches, nylon stand-offs, nylon screws and bolts, solder pins, Veroboard, fibreglass sheet, and project boxes – approx £35
    9. Camera infrared remote control for Sony Alpha – £2.69
    10. Stalk for camera remote IR  – salvaged from flexible USB LED lamp £ 1.98
    11. DVD Rack – salvaged from old DVD player
    12. Misc Lego Technic gear wheels – approx £5
    13. Other miscellaneous electrical components and cable ties – from a box in my shed

    For the chassis:

    1. Aluminium channel 3/4″ x 3/4″, aluminium angle 3/4″ x 3/4″ and 1/8″ aluminium plate – all  from  my shed
    2. S/S and other hardware to hold everything together and three rubber feet
    3. Camera Rack – old Minolta rack lurking in my junk cupboard

    I will cover the software side of things in another post.

    Focus Stacking with a Raspberry Pi – Focus Stacker Circuit Details

    I have finally got round to drawing up the electrical schematic diagram for the focus stacker showing how my Raspberry Pi is connected to the various component that form part of my stacker. Please check very carefully before using any of this information. It works for me but may not for you! The information is shown on this page.

What’s it all about?

Here are my jottings about my photographic projects and activities. I have been working on a focus stacking macro photography rig. There are quite a few posts about that. In addition I write about other photographic activities as and when!


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