A few from the garden

[Nostromo]

This is my second attempt with my extension tubes. It was a rather blustery day so really struggled to keep focus as everything was moving (me included, i think i need to improve my technique).

#1
untitled-176 by Dominic Rodgers, on Flickr

#2
untitled-278 by Dominic Rodgers, on Flickr

#3
untitled-361 by Dominic Rodgers, on Flickr

 

[Orangecroc]

They are pretty good! I'm learning with extension tubes pretty much at the same time as you. I am going to have a go with the shorter focal length lenses, my 70-300 isn't quite so macro.
What is that first one, that's a spectacular looking bug.

 

[Nostromo]

Thanks.
I have know idea what it is, but it was pretty small and quite amenable. The colours are what attracted me to it.
I only have a choice of 3 lenses, 18-55, 50 and 70-300. I found that the 18-55 was the easiest to use, as it focuses quite closely without tubes, so i just use the 36mm tube.

 

[Orangecroc]

Thanks.
I have know idea what it is, but it was pretty small and quite amenable. The colours are what attracted me to it.
I only have a choice of 3 lenses, 18-55, 50 and 70-300. I found that the 18-55 was the easiest to use, as it focuses quite closely without tubes, so i just use the 36mm tube.

I have exactly the same focal lengths. The 50 seems to need to get really close to focus, and the 70-300 i use in manual but can stand back a bit at the expense of magnification.

 

[alfbranch]

The first is ruby tailed wasp and very nice IMO. They are generally a tricky subject and very nervous.
It's never easy when your subject disappears from the viewfinder due to the wind.

 

[GardenersHelper]

Second attempt with extension tubes and a blustery day! Those are pretty good results, well done.

Looks to me like a sensible combination of ISO and aperture to keep the shutter speed up. Have you tried using different shutter speeds for the same/similar subjects? You may find you can afford to drop it a bit from 1/800, which would give you a bit more latitude with ISO or aperture. ISO 800 is probably ok with your 50D and f/11 may be as small as you want to go anyway, but when the light level is a bit lower it could be good to know if/whether you have some wriggle room with the shutter speed.

Have you tried using flash? It can make a big difference even in bright conditions, where it can help to even out the dynamic range and avoid detail disappearing into darkness on the surfaces of the subject that are in shadow.