Interesting combination of TC's on your lens. Having said that, I feel you have lost a bit of detail on the chest area. The head is nice and sharp, and lovely light in the high, together with a great pose. I also like the colours in this Steve.
I think once you start playing with stacked converters your image quality will degrade quite a bit. Though in this instance you have made a pleasing creation out of the file you had captured albeit the light direction is not quite ideal, but almost there. I love the colors, and the BG looks great too. Congrats! :)
I am always looking for more focal lenght but stacking TCs is not possible with my Nikon gear. It is a goodblessing because the examples that I have seen with Canon gear are not very good in terms of image quality. Canon allow TCs stacking but you have to pay a high price: image quality. Do not take me wrong, I have a 2XTC and a 1,4XTC and if my gear allowed me to stack :p... well I am sure that I could not resist to try but image quality suffers a lot and, if I have to choose between reach and image quality you can bet that I will go for quality.:)
I love this species of bird. Have only gotten a few token images of it. That said, the composition is nice; some of the highlights in the perch are blown; and I have to agree with the others: stacking T/C is at best only going to get you more magnification at the cost of resolution. The "circle of confussion" become much more pronounce resulting in even shalower DOF, though ther might be some creative "Boke" effects.
Thanks for the comments. I appreciate the honesty regarding the use of the stacked TCs. I would've liked a bit more detail in this image as well, but find myself drawn more to colors, poses, and comps rather than crisp detail. Of course I'd like to have it all in every pic but like everything else in this hobby, there are trade offs :) Thanks again for the look and comments.