Ok ...
A couple of housekeeping issues first.
Although you seem to be asking about a technique, it still comes down to looking at this image and seeing how it may be improved. Consequently I've moved this image into the image critique section.
On the subject of looking at the image, this site is designed to view images that are no greater than 800px along any side, and also for those images to have a small-ish file size. That permits everyone to download and view the images in comfort. View the WHOLE image. While you've nailed the filesize, this image is way too big to be viewed in full. You will do better in terms of getting responses to your questions if you would review and adjust this aspect.
Getting to the image: you're shooting close and personal here, and for that, you need to have a lot of depth of field. The frog, shot from head on, is a sort of a deep animal, and here we can see that the DoF is quite shallow: the eyes appear sharp, but not the mouth, nor the body.
To get a lot of DoF, you need a small aperture (small hole, high number), and that in turn translates to lots of light. With a light tent, you usually need two, perhaps even three or four light sources, and you also ned to try to direct the light to where you need it to be.
For instance, for this image, I would have used at least three lights. One of those would have been placed to each side of the light tent, and in a plane between the frog and the camera, and a little above the level of the frog, pointing down. These would form the primary light source that's illuminating the frog, and I would have these lights dialled up so that I'm using a good aperture: minimum target would be around f/13-f/16, depending upon the glass, focal length, and the lens's sweet spot.
Remember that as you move out of the lens's aperture sweet spot, you will lose sharpness. That may or may not be significant, depending upon the lens.
Having set those two plights as the main, I would then add an extra light (or maybe two) behind the frog. If just the one, I might place it behind the frog, above the tent, pointing towards the rear of the tent, or I may place it directly behind the tent, facing forward, directly toward the rear surface of the tent. I would probably dial this up by about 1.5 - 3 stops higher than the primary light source, in order to totally blow the background. If this light is above the tent, be sure to use something to direct the light slightly away from Kermit, so that you don't get too much bleed from this light onto areas that you want this light to be: this light's purpose is solely to illuminate the background.
Let's now look at your settings for this shot: 1/50, f/9, ISO 100, on camera and slave flash at 1/16 power.
First of all, shutter speed is largely irrelevant for this shot. You're shooting with flash, and consequently, it's your flash settings that will be driving this exercise. As long as you have a shutter speed that syncs with the flash, it basically makes no difference. With most DSLRs, anything from 1/30 to 1/200 will work. Your actual exposure shutter speed will actually have been something like 1/10000 .... truth be told.
So ... let's now look at at your flash settings aperture. These are intimately involved with one another, so this is adults' only stuff.
Note that earlier I said that you'd need greater depth of field, which also means more light. f/9 and 1/16 power isn't really doing the job. STart with aperture at f/16, set your slave flash to 1/4, leave the on-camera flash at 1/16 (it's only use here will be as a trigger) and try that as your starting point.
Are they the only light sources that you have? If so, washing out the background isn't going to happen easily. If you have other lights, then set them up using the techniques I've described, and see how it goes.
And FWIW, you don't need Kermit as the
model. Buzz or Woody will do well in these sorts of tasks.
g.
Gary Stark
Nikon, Canon, Bronica .... stuff
The people who want English to be the official language of the United States are uncomfortable with their leaders being fluent in it - US Pres. Bartlet
