Webmaster’s blog 2017
Alan Wood’s microscopical diary
The Olympus BH-RLA vertical illuminator for brightfield/darkfield and BH-LHM lamp house came with an Olympus TE-II transformer that is so heavy that it has prevented me from taking it to any Quekett meetings. Now I have a Obh10B LED illuminator from retroDIODE that is much lighter and I used it for a demonstration at the South Thames Discussion Group meeting at Wallington on 4th March.
LED conversion of Olympus 15 watt BH-LHM lamp house
In reflected darkfield illumination, light to illuminate the specimen is piped down a cylinder surrounding the Neo objectives, so they are too wide for an RMS nosepiece and need a special one with 25 mm threads. The CH-2 that I wanted to use at the meeting does not have an interchangeable nosepiece, but it is easy to unscrew it and replace it with the 25 mm version.
The darkfield mode works well with biological specimens including feathers, lichen and pollen on stamens, but the shallow depth of field (around 0.05 mm for the 5× NA 0.1 objective) means that I have to keep refocusing to see all of a specimen. I took series of photographs of the specimens, and combined them using Zerene Stacker, to produce photographs with good depth of field.
Lichen-encrusted twig under the microscope
Stacked image of yellow lichen (Neo 5× objective, FK 2.5× photo eyepiece, stack of 44 images, 1.75 mm depth of field)
Stacked image of crocus pollen on stamen (Neo 5× objective, FK 2.5× photo eyepiece, stack of 42 images, 1.7 mm depth of field)
Stacked image of peacock wing feather (Neo 5× objective, FK 2.5× photo eyepiece, stack of 15 images, 0.6 mm depth of field)
The Obh10B LED illuminator does not only fit the BH-LHM lamp housing for the BH-RLA; it also fits the BH-LH housing for the BHA and BHB stands and fits directly into the back of the BHC stand.
LED conversion of Olympus 30 watt BH-LH lamp house
We tried to get a set of 10 articles for British Science Week, Friday 10th to Sunday 19th March, and just managed it. I wrote 2 of them, mainly using material from the website, on owl pellets and spotted-wing drosophila. I plugged the articles on Facebook and Twitter each day, and we got some nice comments.
Male spotted-wing drosophila
Olympus Zuiko Auto-Macro Lens 38mm f/2.8 @ f/4, 61 images at 40 µm intervals combined in Zerene Stacker
I went to the Reading Convention on Saturday 11th March, always a good event with interesting exhibits and lots of bargains to browse. I restricted myself to a spare bulb for my BH2-MLSH lamp house for £1, and a few Biosil slides at 50p each; I haven’t had time to look at them yet. Mike Samworth kindly gave me a copy of another QMC Monograph to scan for the website, Illuminants and Illumination for Microscopical Work by F. E. J. Ockenden.
I tried to get to Penkridge on Saturday 18th March with Robert Ratford, but we only got to Junction 12 on the M1 before his alternator failed; we had to return on an AA transporter.
On 11th February, Chris Thomas and Dennis Fullwood ran a workshop on making dry mounts of hair, fur and feathers attended by some very enthusiastic members. As usual, I was busy taking photographs and making notes and didn’t get a chance to make any slides, but I have since tried photographing hair under brightfield illumination and crossed polarisers, as recommended by Chris.
Human brown hair (brightfield)
Olympus SPlan 40× objective, NFK 2.5× photo eyepiece, 34 images at 1 µm intervals combined in Zerene Stacker
For the photo with crossed polarisers, I rotated the polariser for maximum extinction, and then rotated the stage to obtain the most attractive colours. The normal BH2-SVR stage on my Olympus BH-2 rotates 270°, which is very useful for composing photographs as well as for rotating specimens under crossed polarisers, even though it is not as precise as a proper polarising stage.
Human brown hair (crossed polarisers)
Olympus SPlan 40× objective, NFK 2.5× photo eyepiece, 28 images at 1 µm intervals combined in Zerene Stacker
I used to use a photographic polarising filter as the polariser (on top of the light outlet on the base), and a cheap disc of polarising film from eBay as the analyser (in the recess where the head’s dovetail fits). I eventually found the proper Olympus A-POL polariser and B-AN analyser at reasonable prices, and they give better extinction and no colour bias.
Olympus A-POL polariser (left) and B-AN analyser
Back in 1980 when Olympus replaced the BH compound microscope with the BH-2, they kept the mounts for the heads and nosepieces but changed the mounts for the stages and condensers. While trying out the vertical illuminator from my newly-acquired BHMJ on my BH-2, I discovered that Olympus also kept the 30 mm fitting for lamp houses on their metallurgical microscopes.
So either of these lamp houses:
- BH-LHM lamp house (6-volt 15-watt)
- BH2-MLSH lamp house (12-volt 50-watt)
can be used with any of these illuminators
- BH-MA Brightfield Reflected Light Illuminator
- BH-RLA Brightfield/Darkfield Reflected Light Illuminator
- BH2-MA Brightfield Vertical Illuminator
- BH2-RLA Brightfield/Darkfield Vertical Illuminator.
Olympus BH2-MLSH (top) and BH-LHM lamp houses
Olympus BH2-MA Brightfield Vertical Illuminator (top) and BH-RLA Brightfield/Darkfield Reflected Light Illuminator
The lamp houses need different transformers, the TE-II, TF or TGHM for the BH versions and the TGH for the BH-2 versions. The metallurgical objectives must be used with the matching illuminators; BH objectives with BH-MA or BH-RLA illuminators and BH-2 objectives with BH2-MA or BH2-RLA illuminators.
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About this blog
I am Alan Wood, webmaster for the Quekett website, and author of several web pages on Olympus microscopes. I spend too much time writing about microscopes and buying more equipment. I hope this blog will help me to focus on using my microscopes so that I have something to write about!