I use the following lenses:
Olympus OM 28mm f/2.8
Olympus OM 50mm f/1.4 ('silver nose' single coated version)
Olympus OM 50mm f/3.5 macro which also has a matched 25mm extension ring.
Olympus OM 200mm f/4.
Schneider-Kreuznach Xenon 40mm f/1.9 uncoated Robot screw mount (circa 1954 vintage)
I am used to using stop-down metering as I have been using manual extension tubes for donkey's years so there was no adaption required for me. Focus first, stop down, take meter reading, take picture. I normally use Aperture priority so the camera sets the shutter speed and with having the onboard IS, this works a treat.
One of the few problems is that on some lenses, the meter readings are not accurate when significantly stopped down. With one of the lenses, I am pretty certain that the aperture itself is not closing down for the last stop.
I find manual focusing easy but having used an interchangeable rangefinder style camera (that didn't have a rangefinder), I am also comfortable with judging distance and setting it on the focus scale anyway. I have set the E-P1 up to easily switch to MF with a single press of a button and limited the view settings so toggling between the MF zoom screen and the standard screen is quicker (the only other screen I have come up is the level screen). I really like the 7x and 10x zoom focus options and don’t mind the low resolution of the 3” screen either. It is rare that it isn’t sufficiently viewable and is nice and bright with lenses of f/2.8 or larger at night.
As far as legacy lenses go, I have found that lens quality varies a lot and some of the lenses don’t fare well by modern standards.
The single coated Olympus OM 50mm f/1.4 suffers badly from flare and has too frequently has contrast issues and suffers from a small amount of haloing. I will be selling this lens. My 40mm f/1.9 Schneider and Panasonic 20mm f/1.7 give me sufficient coverage in low light and are more useful. I find the 50mm lens too long for general use.
The Olympus OM 200mm f/4 is a bit on the soft side and doesn't focus close enough (minimum distance is a pathetic 2.5m}. Infinity focus is also not the sharpest in the world. I picked up a Komura Telemore II 7.K.M.C teleconverter to use with this lens to take moon shots but I get a sharper and more detailed picture using my Pansasonic 45-200 MFT zoom and cropping the image. I no longer need this lens and will be selling it. Of the OM lenses, the teleconverter only mounts with the 200mm and 50mm f/1.4 lenses for some strange reason so it will be going too.
Now the success stories. The Olympus OM 28mm f/2.8 is a little ripper. It is affected by flare but not as badly as the 50mm f/1.4. Contrast is good as is the sharpness. I used this quite a bit before I got my Panasonic 20mm f/1.7. The 28mm f/2.8 is a lovely little lens and a definite one to keep.
The Olympus OM 50mm f/3.5 macro is very sharp and plenty of contrast. Sharpness is on a par with the modern digital lenses. My only disappointment is the close focus of 0.23m doesn't bet me a lot more magnification than I can get out of the kit Olympus 14-42 MFT lens (0.25m at 42mm) but after mating it to the 25mm extension ring I now get 1:1 magnification. That has worked out as a very cheap macro setup and as I don’t do a huge amount of macro work, will probably satisfy me for many years.
The Schneider 40mm f/1.9, well it may be uncoated but as long as you are careful where the sun is, a great portrait lens. Contrast isn’t brilliant but fine for portraits and the limited depth of field at f/1.9 can be put to good use. I have had this lens for almost 30 years and the E-P1 gives me the opportunity to put it to good use. Very compact, shiny chrome and also very heavy for its size with collapsing lenshood branded ‘Robot’, it makes a very handsome compliment to the E-P1 and raises a smile on many a face. My favourite ‘other’ lens and MFT is about the only modern mount that will take it.