Something on the sage bush

There are a few of these on the sage plant, about 3mm long but no idea what they are. K50 + Pentax 100 mm macro lens with Vivitar 2x teleconverter and ring flash on tripod.

Here is another one, same set-up as before but tried focus stacking 3 images and merged in Lightroom.

Still not getting the degree of sharpness I am after, so it's either equipment or eyesight and I am betting the latter!

I would suspect that the 2x converter is what is killing the sharpness, plus a little bit the flat lighting that ring flashes produce. I think you need a small additional flash at 45 degrees to just add a bit of contrast and a highlight. This works well for images of teeth in the mouth where without it you get lifeless lighting.

If you use Live View, you can enlarge the image, using the INF button and get your focus spot on. I would also suggest a set of bellows rather than a converter. K fitting ones turn up now and then on Ebay and M42s are ten a penny

The critter in the first image has an alien face on its back