Pushing the tools - Extension tubes

[JAS]

Just for fun I tried something new for a few shots. Shot laying on the wood chips nex to a small preformed pond in our yard. We have many frogs that have taken up residence along with our goldfish.
Set-up as follows Nikon D850, set of Vello extension Tubes totalling 68mm, Nikon 500mm f/5.6 PF lens.
Focus is soft. Not sure if that is me or the setup but think the issue is me.
Shot is uncropped, 1/80 sec, f/16, ISO 3200. I will try again with a light source to drop the ISO and up the shutter speed.
May also try with the Z6 so i can use manual focus with the assist.

You can see the corner of my house in the frog'

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[Woody Meristem]

She's a beauty. That's a lot of extension, I've noticed a fall-off in sharpness when using a bunch of extension tubes -- don't know why.

 

[bleirer]

Thats a nice shot. Unfortunately the tubes don't add much magnification to a 500mm lens, you could possibly have done without and still gotten a good shot. The usual rule of thumb is to divide the extension amount by the focal length and add back whatever native magnification the lens had. I believe that lens is .18x as is. So 68 mm of extension only gives roughly .13x more than the .18 you started with.