Fade is not linear?

sorry for the dumb question but If I fade a material I would expect that 0.5 opacity would be 50% see-thru. However it looks 50% see-thru when the fade value is only 0.1. How do I get around this - I want to change smoothly over time. With this dynamic material and a timeline, it fades in waaaaay too fast.

If not mistaken it’s because of the emission remove it and you see that it’s really 0.5.

Good point thankyou!