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For best results Dave you'll want to experiment a bit. Ronny is hand holding these shots, if I'm not mistaken. The issue with tubes is that while they allow you to get closer to your subject, and thereby filling the frame with the object. the focal plane narrows and you lose infinity focus. That means you'll need to find a distance to the subject that allows the lens to find focus. Most often those using a tripod will have a focusing rail that allows the camera to move closer and farther back as you find focus. Shooting hand held in some ways is easier because you can rock back and forth, or lean closer and farther back to find focus.
This is one of the reasons AI lenses are attractive. They tend to have a longer focus throw, which increases the possibility you will gain focus simply by turning the focusing ring. Of course, we will always opt for the 180 with ED glass before the AI version that doesn't have that feature.
You'll find it useful to stop down and possibly shoot in manual mode to keep the shutter speed up. When I'm shooting with the much slower 300 f/4.5 AI-s ED-IF even in bright sunlight, I'm generally shooting manual mode and relying on Auto ISO to give me enough light.
Shooting with tubes is great fun, but it is something you really learn by doing. You might find the tripod less an advantage than a disadvantage for tubes, but you'll only know that by trying. Have fun!
Here's a shot with the 300 and a 36mm Vivitar tube attached...
Manual mode, 1/400th of a second, wide open, ISO 360