I was trying to get some head shots at five times life size of this lethargic Sawfly when it woke up and started feeding. The framing was just too tight at 5x to get the critters mouth parts, so I took a risk and backed the camera out, dialed the MP-E 65mm down to 4x, and brought the camera back in to get a shot. I got lucky and didn't spook critter into taking off. The tricky part is tracking a moving subject when the frame at 4x is only 5.7mm wide by 3.7mm high.
Tech Specs: Canon 80D (F11, 1/250, ISO 100) + a Canon MP-E 65mm macro lens (around 4x) + a diffused MT-26EX-RT with a Kaiser adjustable flash shoe on the "A" head (the key), E-TTL metering, +1/3 FEC, second curtain sync). This is a single, uncropped, frame taken hand held.