Illumination for stereo Zoom for Micro Minerals

[Gatorengineer64]

I about have my Oly SZH10 dialed in, and am incredibly happy so far. The one thing I am not thrilled with, is the illumination. I needed a ring light and I bought an Amscope something or other. It just seems to be really harsh, maybe by definition that's what you get. What would be the best illumination for a scope for microminerals? Thanks

[MichaelG.]

Fossil Crinoid, approx 3mm ‘diameter’ : Much reduced resolution

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Is this the sort of lighting you need ?

If it is, then I’m happy to describe the very simple set-up

MichaelG.

[Gatorengineer64]

That would be a huge improvement over what I have....... So yes please.

[MichaelG.]

I used one of these little ‘mini bulb’ LED lamps which were available very cheaply on ebay three or four years ago:
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MINI BULB, from ebay

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They are about 3W and have an excellent hemispherical diffuser, about the diameter of a golf-ball
They’re USB powered and have a magnet in the base.

What’s not to like about all that !

The ‘trick’ [if it merits the description] is to direct the axis of the lamp at about 45° to the surface of the subject, so that any strong reflections are directed off the optical axis of the ‘scope. … This is similar to the arrangement traditionally used for photographic copying of documents.

You should be able to achieve similar lighting with any well-diffused lamp of similar diameter.

MichaelG.

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Edit: __ The copy-stand arrangement is shown here: http://cafamilies.org/reference/photo_doc.html
‘though for our purposes, a single lamp gives some modelling, and usually works best.
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Update: I’ve just found an ebay listing [at a higher price than I paid] : https://www.ebay.co.uk/itm/363406803913

[Gatorengineer64]

Thanks that may work well for the flatter specimens, but most micros are pretty craggy. Maybe that bulb with a whole cut for the path of light. I get the idea of difuse

I was also wondering if I could somehow rig up a darkfield ring light.....with a lot of the micro crystals and such that could be impressive.

[Scarodactyl]

I typically use dual gooseneck light guides from a 150w fiber optic halogen illuminator, diffused with a tube of wax paper.
For ring lights one trick is to put a polarizing filter on the ring light and an rotating polarizer on the objective so you can cut down specular reflections as needed. Ring lights are often not the most aesthetical in their illumination of these subjects in general.

[MichaelG.]

… that may work well for the flatter specimens, but most micros are pretty craggy.

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Could you show a typical example of a ‘craggy’ specimen, please
… I would like to approximate your use-case.

MichaelG.

[Greg Howald]

The biggest problem I have with a ring light is the light reflecting off the specimen directly into the objective lens. You can soften this by having the lighting come in at a slight angle. I use a gooseneck, dimmable LED desk lamp to achieve that. But before you spend more money you can try it out.
Remove the ring light so you can hold it in your hand. That way you can adjust angle and distance to see if that type of lighting would help.
Greg

[Gatorengineer64]

I have no means of shooting through my scope right now but below is a sample shot in a light box with a below macro lens. (I have a ton to learn on macro photography as well.) The field of view is roughly a half inch but defines what I mean by craggy.

I like the wax paper idea and I see two votes for goosenecks....

[MichaelG.]

Thanks

MichaelG.

[MicroBob]

One way to generate very soft lighting is to cover the specimen with half a table tennis ball or a cut down white plastic cup with a hole in the top, both with lamps around them. I think for your sparkling minerals this would give a nice illumination without harsh highlights. Since the opaque material is diffusing strongly the number of lamps can be quite low.

Bob