025: Glass & Metal

Another combination of metal and glass here, but using much more magnification this time - a detail of the rear section of a cathode ray tube from an old oscilloscope. The extreme close-up of this detail is quite industrial-looking, like laboratory equipment.
I used a total of 46mm of lens extensions for this image (including M42-PK adapter), at settings of f/11, 1/180 sec. ISO 100, low power flash. Afterwards I increased the contrast and sharpness, and also corrected the rotation slightly.
I got curious about the magnification ratio of my thrown-together setup. The width of the glass rod on the final uncropped image is 1128 pixels. The 10.2 Megapixel Sony APS-C CCD used by the Pentax K10D is reportedly 23.5x15.8mm. Raw Therapee outputs a full image at 3888x2608px, so that works out at about 165px/mm.
With a ruler I got an approximate measurement of the actual rod as 7mm.
If I presume the ratio is 1:1, the glass rod's width would be 1128/165 = 6.84mm.
So the approximate magnification ratio is 7/6.84 = 1.024:1. That's near as anything a 1:1 ratio. Pretty good considering I paid next to nothing for this lens. The detail is very sharp at the plane of focus. I reckon the contrast's a bit lacking, but this may have been because of glare from the flash light - I had it reflecting at a few different angles in this shot.

I really should get out my bellows with a reversed wide-angle lens and start shooting at some near-microscopic levels.