Quote Originally Posted by baachitraka View Post
...and OM-2 and OM-2n have off switch but OM-2sp not.
Yes, but the off switch on the OM-2/OM-2n doesn't cause it to really work all that differently from the OM-2s.

If you pick up an OM-2/OM-2n that has been turned "off" and take a photo, it turns the meter on to set the exposure.

If you leave any of the three cameras "on", they will turn themselves off after a short time.

As a matter of practicality, all three cameras depend on the "auto-off" circuitry to save batteries.