In article <54id0t$kc@sci.cpd.uniovi.es>, julio@pinon.ccu.uniovi.es says...

>I have a medium format (18x24) Olympus PEN EE-3 camera,
>and I think that is focus free. But at what distance is focused?
>3, 4, 5 meters?

Ummmm, I wouldn't refer to 18x24mm as "medium format"....! ;-)
It is usually called "single frame", or "1/2 frame".
My guess is that the fixed focus was set (in the two Pen-EE2's
that I owned with the same lens) at no more than 3 meters.

>I also think that the exposure speed is fixed. What speed is used
>in this camera? 1/60, 1/125 seconds?

I can't remember, but I think it was one or the other....

>What resolution has the Zuiko 28mm/3.5 lens of this camera?

Mine were very sharp.

>The resolution of the prints from negatives
>exposed in this camera depends on this data.
>In example, I think that a print with flash
>at low distances must not be enlarged over 10cm x 15cm.

Good sharpness (with large grain) could be had in larger prints,
if the aperture was not too wide, and the subject distance not
too far from the lens fixed distance. BTW, the Pen EE2 was my
first 35mm camera, and it saw me through my early photography,
shooting slides. The VF was so bright and crisp, it was hard not
to keep taking pictures with it - everything looked so good in
that finder!
Hope This Helps