Is is possible to set FIXED_AUTO zoom on the Y or X axis only?

Questions
#1

For example:

if message.height/message.width >= 1 and message.width > 730 and message.height > 1050 then --portrait mode zoom setting
			msg.post("main:/camera", "zoom_to", { zoom = 1.4 })
		elseif message.height/message.width >= 1 and message.width <= 730 and message.height < 1050 then --portrait mode using auto zoom setting
			msg.post("main:/camera", "use_projection", { projection = hash("FIXED_AUTO") }) 
		else --everything else uses auto fit (landscape and small portrait)
			msg.post("main:/camera", "use_projection", { projection = hash("FIXED_AUTO") }) 
--I need FIXED-AUTO but then also zoom if in portrait mode. In other words I want to FIXED_AUTO to the X axis only 
		end

In fact, if I could figure this out I could get rid of the different clauses and just use the vertical auto zoom.