OK, I'm sure a couple of you out there may want to slap me for this but I wanted to find out how far I could extend macro tubes before the results were no longer usable.
I've asked on the forum before and many people were very helpful in providing me with the necessary equations to work out the magnification. I wanted to know what the real-world usable maximum was. So I got my scissors and tape, collected a bunch of toilet paper rolls and made the most stupid length tube I could, using my existing 50mm of tubes as mounts.
I know the construction sucks, they're not perfectly straight and there was light leaking in but screw it! I got the results I wanted and now I'll go buy the proper tubes for the length I want! The total length of my ridiculous construct is about 15 inches (mount to mount) and working distance from the lens was the same as usual at about 2 inches.
Here are the results!
In case you're wondering, those are my fingerprints! There is a slight blur because if you move even a micron, it shows.... You're heartbeat is enough to move you a micron.
The last shot is the mm of a ruler