The relationship between shutter speed and f-stop is fixed. if you open your shutter, making the number smaller, you must speed up the shutter. Because there is only one proper exposure for the lighting of the scene. Now the larger the f-stop number (usually around f22) the greater the depth of field or the more stuff that is in focus. This is all true for normal film cameras or digital cameras.
Now the beauty of Digital cameras is that you can white balance the camera to a variety of different lighting and some have several custom settings. But the camera can only look at one light source at a time. so if the MH are illuminating the majority's of the scene but the Actinics are picking up the shadows the camera can not compensate.
So try to perform a custom white balance before you shoot the pic.
J
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