Short story, this is an experiment with the old S82 close up lens with my 100F2.0 lens, converting its min focus from about 0.16x at 30" into about 0.32x at 16" working distance, pretty sharp from what I can tell with my hand-held free-lensing experiment. Time to get a filter thread adapter to try it properly. This example is a heavy crop at 2400x1600 pixels, re-rezzed to 1200x800 for posting.
I have read people mentioning some of the acromatic close up lenses, and I haven't seen anyone mention the Pentax SMC medium format lenses on this forum. I happen to still have an old S82, which appears to be an acromat with 82 cm FL, originally built for standard lenses for their 6x7 system, so they advertised it for use with the 90 and 105 mm lenses. This makes it about 1.22 diopters. Their T132 and T226 lenses were intended for telephoto lenses, 150 through 200 mm lenses. I have tried free-lensing the S82 in front of my 300F4L IS, and the IQ is "dreamy" so I don't use it much for that. On my crop camera, it converts the roughly 3.5" wide (horizontal) frame at 50" min focus into about 1.5" wide framing at 20". It would be attractive if the IQ were better.
The yellow jackets are out now that it isn't freezing at night, and I decided this week that I should get some entertainment out of the little beasts. They are crawling all over the teak wood furniture of our little courtyard. I don't have a proper macro setup, but I do have two really old super Canomatic lenses, a glass-less FD to EOS adapter, and a 15mm FD extension tube. The old 35F2.5 lens can get up to about 1" framing with the extension tube, or about 1.75" framing with just the adapter, both around 2" working distance. The old 50F1.8 can get about 1.5" wide framing at 4" working distance with the extension tube, or about 2.25" framing at 8" working distance. The 50mm lens with and without extension tube worked well for chasing the yellow jackets around, that is primarily what I used. Almost too contrasty in the bright sunlight though, I need to work on a diffused lighting setup.
I remembered the S82 and I just got the 100f2 this year, so I decided to try it together. The 100F2 with the S82, even hand-held free-lens style, was surprisingly sharp. I guess being the right FL for the S82 helps, it is vastly better than my experiments with the 300f4L, too bad about that, 20" working distance to get about 0.7X would have been really nice. The 100f2 with S82 has similar magnification to the 300F4L, and about 20" rather than 50" working distance. But I don't always have the 300F4 with me, often on walks I often take the 100F2, very compact, sharp stopped down, lets me get birds with some background/foreground rather than just the bird alone. So carrying the S82 would be a great addition to get flowers, bugs, etc.
And zooming in, I now know why the yellow jackets are all over our furniture every Spring. Everyone reading this probably already knows this, but they are clearly collecting wood pulp to build their paper nests that I knock down mid-summer. You can see the yellow jacket pulling on the fibers with its jaw in this and in other pictures. Back in NC, where I grew up, they live in the ground where they swarm up when you mow the lawn and chase you around the yard, but here in CO they build the little open-cell paper nests (maybe a different species?). Metal furniture, anyone?