* Annika1980 wrote :
On Jul 23, 8:04*pm, Troy Piggins wrote:

Lately I've been shooting with full set of extension tubes on,
and I realise you lose infinity focus, but I've been wondering
what the minimum magnification really is.

I was out trying to shoot eagles one day and I had the trusty old
Vivitar 2x on the 400 f/5.6. But for some stupid reason I couldn't
get the damn lens to focus, even manually. My 400 f/5.6 has some
focus problems anyway (it slips when focusing manually so using TCs
becomes quite a challenge), but all I was getting was a blurry
screen. I checked every setting I could think of and couldn't figure
out what the hell happened.
I even went through all the Custom Functions to see if I might have
set something screwy. Then I finally noticed that the 2x wasn't the
2x at all, but was actually my Kenko 36mm extension tube that is the
same size and color as the 2x.

Oops!

Haven't heard that one before! I've got the Canon TCs.
They're white, metal, and much heavier than the Kenko black
plastic tubes.

--
Troy Piggins
I always appreciate critique.