On Jan 29, 1:29*pm, mike wrote:
Powered diggers are excluded.

Which is the better choice for various soil condition in your
experience?

1. *The manual auger that you twist until you get a full load of soil
to dump:

http://www.hooverfence.com/tools/adjust-augers.htm

(Needs room for handle, but can go very deep by using pipe to extend
it)

or

2. *The clamshell-type post hole digger, like this dandy by Fiskars:

http://tinyurl.com/cna8js

(reportedly reaches over 4 feet)

Augers are extremely hard work. The tool is heavy, the soil is heavy
and your back will suffer accordingly. Clamshells do the job, but are
slow, slow, slow.
Many years ago, the phone company trucks were supplied with a matched
pair of special shovels for post holes, referred to as 'spoons' by the
technicians. The handles were some 6' long IIRC. When I was using my
trusty clamshell digger for setting the posts on a business sign some
years ago, a friend stopped by and sympathized about the difficulties
of going below the three foot depth. A short time later he came back
with his 'spoons' and in a half hour or less had both post holes well
below 4 1/2 feet. I have no idea whether such tools are available
today, but that one demo was quite impressive.

Joe