pinhole or not/project advice

hello list,
ive been experimenting with pinhole photography for awhile,
and it dawned on me... what is a pinhole?
i mean, what size constitutes a pinhole? smaller than f/64? f/128?
and what about lens-less photography?

allow me to explain...
i have been working on modifying a fed-2 camera, which is the poor persons
version of a leica 2 or 3, a russian counterfeit if you will.
i have removed the glass lenses and repositioned the aperture leaves to
close them down as much as possible and im still trying to calculate the
size, which may be approximately f/64, or f/90... or even f/128.

a lot of my results have been completely over or under exposed, although i
finally got a good range a few days ago, but i seemed to be limited with
time.
i shot with ilford pan f 50 (velvia exposures seemed too inflexible) with a
one second exposure seeming descent on a NYC afternoon with good light and
distinct shadows in central park.
now a fed goes from 500 - 250 - 100 - 50 - 25 to bulb, so a few seconds are
difficult to work with, suppose my aperture is not a pinhole then, eh?

another factor that i am working on is that of focal length.
the lens i use is collapsible but is 50mm fully extended from hole to film
(and approximately 62mm in distance with a pinhole lens cap) and collapsed
is about 29mm (41mm with lens cap pinhole).
now when i tried shortening the focal distance i get vingetting (did i spell
that right?) as well as some overexposure.
the one frame that was exposed well at 50mm is completely out of focus,
beyond an artistic look and towards the myopic...

well, my apologies if this has been too lengthy, i have researched and
experimented for quite some time and am unsure if i should just abandon 'the
converted fed-2 project', so if your up for a challenge or have any
experience and/or advice, please let me know if i am way off or just need to
keep at it.
thanks...

-- 
segoss
http://www.nought.org