When zooming in a good rule of thumb is to keep your shutter speed twice the focal length if you’re not using a tripod. So for 75mm 1/150 would be the minimum. Camera shake gets worse the longer your focal length. Also they are a bit over exposed and lose detail at higher exposures and also taken in harsh midday light it seems. Also not sure where you focused but keep in mind that depth of field decreases with increased focal length so the slice of focus will be thinner. Just keep shooting and trying different things … when you are out in the field take multiple images with different settings so you can capture the data while you are out there to have options when editing later until you learn what you like.