I spent almost 45 minutes shooting this Great Blue Egret. I started out at 600mm with a TC20E-II and had one of those rare moments in birding- I had too much reach!

I then shot the bird using the TC14E-II and the lens alone. All images shot with a Nikon D70 on a Gitzo 1228 with Markins M10 Ballhead and TB-20 base plate. Lens with Kirk replacement collar. I was experimenting with putting "bean bags" on the lens for stability. Actually 2 large zip lock freezer bags partially filled with about 2 pounds of local beach sand. I am sure that I used the sand bags for the 600mm image, and possibly the others. I think that helped a lot, especially since the shutter speed of 1/125 on the 600mm image was a bit low for that focal length. All three images were shot at an aperture of one stop down from wide open, which until I spend more time with each combination seems to be a good rule of thumb.

All images shot in NEF with in camera sharpening set to normal. No additional sharpening. The 600mm image was shot at ISO 200 (probably should have used 400) and the other two images at ISO 400. Exposure as indicated on the exif. Saved as JPG "good balance" quality in Nikon Capture. The 300mm image was very much overexposed; very unusual for the D70 matrix metering. I adjusted it -1 ev in post.

All three images are uncropped and full resolution. You can see that I got a little closer with the 420mm. I was varying my distance slightly and my position to catch the light as he also moved about within a small area. There are differences in lighting that are unavoidable in a real world shooting situation. This is not a test chart!

I can see no significant differences in sharpness between these images. I cannot say that for all my 600mm images. That tells me that technique may play a large role in the varying opinions of this lens and TC combination. I cannot say if any/all of the images could have been better; only that this is what I and my camera was able to do on that day.

2-10-2007 - I replaced the 600mm and 420mm images with new JPGs rendered from the same original NEFs, with about -1/3 stop exposure compensation. The original images were somewhat overexposed. I replaced the 300mm image with a JPG rendered from a different original NEF, with slightly better exposure. The images are otherwise as shot out of camera, with "Normal" in camera sharpening.