Try to use just a usual microscope (to observe a water drop on the film surface).
If the surface of the thin film is hydrophilic, I would strongly recommend to use any Contact Angle Goniometer.Here water droplet is injected from a syringe using the software and the moment water droplet touches the surface, an image can be captured and angle can be measured in computer screen using the software provided by the Goniometer. Hydrophilicity can drastically change contact angle within 3 seconds, hydrophobic surface takes more time to change the angle. Thus, time delay to measure contact angle will give inaccurate results.
Sometimes it may make sense to measure time-resolved, with a simple microscope-camera or the like, if there is a time-dependence of the droplet form on a time scale of seconds to minutes.
And for such a "free-hand" experiment - without commercial equipment - it is a good idea to keep the droplet volume constant (e.g. ~ 18 micro liter give quite a round shape on rough hydrophobic surfaces).
Use a USB laptop camera and a bright&homogeneous backlight camera. For increased resolution, make sure you have a spherical drop and calculate the contact angle from the base diameter and drop hight.
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