It’s not difficult to scare a tree frog, especially the little ones. Stepping on some of the lower branches or positioning a tripod leg in the bramble bushes can be enough to scare them.
That’s why I prefer to use a 180mm lens instead of my 105mm macro lens. But even the 180mm forces you to position yourself close to the branches and then carefully bending over to get close enough . To my knowledge there are no real macro lensen above 200mm. So to keep even more distance I tried to (ab)use the AF-S NIKKOR 300mm f/4E PF ED VR combined with an extension tube.
The positive news is that the 300mm focal lenght usually allows you to position the tripod beside the bramble bushes. And 300mm at f/4.0 povides shallow depth of field. So what are the drawbacks? Don’t expect macro like behaviour. The extension tubes messes up autofocus (not a big issue just focus manually) and with a thin extension tube you can get pretty close but your not getting the 1:1 reproduction. So the lens forced me to frame with a lot of room around the subject, which is not a bad thing. The image not only shows the subject itself, but also it surroundings.