1 Introduction

The importance of the Carina Spiral Feature in understanding the structure of our own Galaxy has been stressed by Bok (1932) and has since then been emphasized by many others. As pointed out by Graham 30 years ago, the Carina section of the MW is the most promising of all fields for the optical study of a single large scale feature of the Galaxy (Graham 1970). The Carina Feature is spread out over a distance of several kiloparsecs along the line of sight and may either be part of a major spiral arm, or may represent a strong inter-arm link. A large number of prominent young open clusters and OB associations are found over a wide range of distances and have also been intensively investigated. The Feature is situated beyond 500 pc, i.e. beyond the limits of the Hipparcos survey (ESA, 1997), and so far photometry remains the most efficient tool to study its characteristics. The observations presented in this paper are aimed at improving the completeness of the Strömgren and H$\beta$ data of O and B type stars, generally brighter than 9.5 mag. The field under consideration is within 5 degrees from the Galactic plane, bounded between $l=285^{\rm o}$and $l=295^{\rm o}$.