I'm having an alignment issue with radio buttons. I want three columns of form elements. For some reason, when I add radio buttons to the form, they appear to take up space for a new column on the left. I was hoping for a simple grid layout with each cell having equal size. That doesn't appear to be the case. Any suggestions would be greatly appreciated!

Here is part of my code:
self._mode_state = StringVar()
self._mode_radio_timelapse = Radiobutton(self, text="Timelapse", command=self._transition(), value=self._timelapse_mode, variable=self._mode_state)
self._mode_radio_continuous = Radiobutton(self, text="Continuous", command=self._transition(), value=self._continuous_mode, variable=self._mode_state)
self._mode_radio_ramphold = Radiobutton(self, text="Ramp and Hold", command=self._transition(), value=self._ramp_hold_mode, variable=self._mode_state)
self._mode_radio_timelapse.grid(row=0, column=0, pady=10)
self._mode_radio_continuous.grid(row=0, column=1, pady=10)
self._mode_radio_ramphold.grid(row=0, column=2, pady=10)
image_set_label = Label(text="Image Set Type: ")
image_set_label.grid(row=1, column=0, pady=10)
self._image_set_type = Entry()
self._image_set_type.insert(0, "Ramp")
self._image_set_type.grid(row=1, column=1, pady=10, columnspan=2)
columnspan=2fromself._image_set_type.grid?