I hope this doesn't get dumped as off-topic, but it is about 35mm lenses.
A friend of mine plans to do some whale watching, but he has only a modern follow-on to the fabulous Olympus Pen model with a non-film light receptor 18 x 13.5 mm. He is looking at longer lenses than he has, but is choking on the prices of the new auto-everythings. I made him aware that all the old manual OM lenses would still work on this camera. I am wondering how the shorter distance to the "film plane" and the smaller size of the non-film receptor affects the operation and performance of the lenses. Does the adaptor for these lenses correct for the distance? Does it then just act as if the camera has a mask down to 18 x 13.5?
Focusing works fine, but be aware, its manual only and those little 'non-film' cameras are a pain to manually focus. As for field of view, it acts like the film has a mask down to the sensor size, so his wideangle lenses will no longer be very wide, but his longer lenses will be 'longer'
Yep. Your friend is best of buying an OM film body and shooting film if he wants to use his OM glass, and buying Micro 4/3 glass if he wants to shoot the new camera.
There is nothing in the original post to indicate which model. Only the E-P1 cannot use the VF-2, all following models can. That is why I used the word 'If' in the reply, I did not know which model he had.