Gossip meeting (no theme)

Tuesday 14th September 2021

NOT FINISHED

Quekett members can watch a video recording of this meeting.

Much of the meeting was devoted to discussing slide making, including LOCA and glycerine jelly mountants. There will be a demonstration at Quekex by Gordon Brown and ???, and there was interest in a face-to-face meeting where beginners could learn some of the techniques. One of the proposed 3 meetings at Northampton in 2022 might be suitable.

Paul Smith showed some photos taken by him and Joan Bingley during the Bank Holiday Microscopy Weekend at Cranedale Centre and the joint meeting with British Phycological Society at Malham Tarn.

Cosmarium sp.Cosmarium sp. at Malham [by Paul Smith]

Sampling from the boardwalkSampling from the boardwalk at Malham [by Joan Bingley]

You can see more of the photographs in the meeting reports:

Michael Bradley showed a series of images of Haematococcus pluvialis that he sampled from a friend’s brass birdbath in British Columbia and observed over 15 days as they transitioned from the green motile form to the red encysted form.


Click the arrows to move through the slides. Click the symbol at bottom right for a larger version.

Jeffrey Silverman showed us two of his recently-acquired antique microscopes, a Carpenter’s Improved, Opake and Transparent Compound Microscope – Achromatic version manufactured by Carpenter & Westley around 1837–1840, and a Beck & Beck microscope.

Carpenter’s achromatic microscopeCarpenter’s achromatic microscope

Carpenter’s achromatic microscope compendiumCarpenter’s achromatic microscope compendium

Alan Wood showed the Olympus full-wave and quarter-wave tint plates (retarders) that fit his BH2-KP intermediate polarising attachment (and also fit the more elaborate BH2-PA version), and compared them with some of his makeshift retarders cut from a variety of plastic films.

Olympus full-wave and quarter-wave tint platesOlympus full-wave and quarter-wave tint plates

Makeshift retardersMakeshift retarders

It is easy to rotate the makeshift retarders (assorted plastic films attached to card annuli) because they just sit on the light output in the base of his Olympus BHT microscope. The tint plates cannot be rotated, which limits their use for pictorial effects, but the specimens can be rotated because the standard BH2-SVR stage rotates through 270°.

The slide that Alan used was a thin section of quartz diorite by an unknown mounter, and he showed photomicrographs taken through crossed polarisers plus retarders as well as live images through his Olympus BHT microscope and Canon EOS 5D Mark II digital camera.

Thin section of quartz dioriteThin section of quartz diorite

Quartz diorite, crossed polarisers plus quarter-wave retarderQuartz diorite, crossed polarisers plus quarter-wave retarder

Quartz diorite, crossed polarisers plus full-wave retarderQuartz diorite, crossed polarisers plus full-wave retarder

Quartz diorite, crossed polarisers plus makeshift retarderQuartz diorite, crossed polarisers plus makeshift retarder

Quartz diorite, crossed polarisers plus makeshift retarderQuartz diorite, crossed polarisers plus makeshift retarder

Some of the makeshift retarders gave interesting results, but none of them were as spectacular as the full-wave retarder. The Quekett Shop sells 2-inch squares of full-wave retarder that should provide very similar results to the expensive Olympus version.

Alan also showed a conoscopic image of a sheet of mica, the first one he had managed to obtain. He does not have a Bertrand lens, but the instructions for the BHSP polarising microscope explain how to observe a conoscopic image using a pinhole eyepiece or a phase telescope, a 20× or higher objective and the iris in the substage condenser wide open.

Conoscopic image of micaConoscopic image of mica

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