Just a quick test at Yiti beach to see how much M42 nebulosity I could capture under less than ideal skies (as are available in the Oman mountains). Nine frames, each 5 minutes exposure at ISO 1250, Canon 1Ds, Canon 600mm/4 lens + 1.4x extender, yielding 840mm at f5.6. Dark-subtratcted and flat-fielded. The core of M42 gets washed out in a 5-minute exposure but I blended in another core from a previous exercise. The full frame is in portrait mode but I cropped the top and bottom.