Camera Labs

so i recently found a contax tla 360 strobe in my attic, which seems to fit onto my nikon d90 just fine. my only problem is, i seem to have a problem controlling where the flash goes. i seem to only have success using the flash in a dark room with the aperture at f/25 or so and the shutter speed quite fast. in other situations, the flash makes the top half of my picture bright, leaving the bottom half dark. is there anyway to solve this problem?

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Nikon D90, 18-105mm 3.5-5.6G, nikkor 70-300mm G, nikkor 50mm 1.8, nikkor 80-200mm f/2.8, contax aria 70 years edition, contax 45mm 2.8 MF lens, contax 80-200mm f/4 mf lens, contax tla 360 flash

i love it when gordon laing says "in practice"