The Talking Machine Forum — For All Antique Phonographs & Recordings

The depth of field here is about 7mm and it's a focus stack composite of 720 separate microscope images, so each image was taken after advancing the focal point by an average of just 10 µm (microns) at a time.
I hadn't realised how flat the grooves are at the bottom of the groove, or just how dirty they are too, and this was giving the record a thorough wipe down beforehand.

The music is When It's Springtime in the Rockies by C. D. Smart on a Wurlitzer organ, released October 1930, if you wanted to know!

Iain

Astounding and fabulous again, thank you so much Iain!

Wow! Wonderful work with the camera, microscope and computer!

Thank you!

I find it very interesting how the contour of one side of the groove does not match the contour of the other side. Or perhaps I'm not identifying the peaks & valleys correctly?

Yes, it is a bit strange, and the needle seems to be riding half way at the groove wall... Maybe it's an effect created by the image composition

Yes I wonder if the point is sitting in the groove or is actually between grooves?

Yes, the needle is sitting on the flat area between grooves. The light lines are the grooves and, to me, look like they are showing wear at the bottom, or maybe that is just dust/debris.
Below are a couple images from the web of 78s close up.
There has to be a relatively wide area between grooves so loud, high amplitude passages don’t encroach on the adjacent groove wall.

As old as this technology is, analog recording still amazes me. "Squiggles" that produce sound, from a single piano or human voice to a full orchestra . . .

Certainly... I'm also thinking always on this. Being so simple old Egyptians could have invented it 6,000 years ago...

Thanks for the comments guys. I should say, the needle and record was under the microscope and the needle was not "in play" rather was just supported there with a homemade mechanism including miniature clothes pegs, so sorry if it's created confusion!
Having read the above, I'll try again, and with some different needles too, and with the needle fitted correctly into the soundbox and arm , if I can find enough space to work with.
Iain