Gradual neutral density filter problems

heres another solution
invest on a speedlite

What are you trying to accomplish? A graduated filter would work for the last two pics. The best option for the two portraits would be to just light the subject, else why not just expose for subject and attempt to fix highlights in post?

An ND filter is something that simply blocks light. What those pictures are facing is a dynamic range limitation, which you'll find on every camera you use.

The solution as people have stated above is to use a flash, so that the dark subject is illuminated enough to match the background, therefore shortening the gap between both exposures and making the camera able to capture both.

Long story short: if you try to capture a very dark and a very bright subject at the same time you can only get the bright one correctly exposed and a black spot or the dark one correctly exposed and a white spot.
Illuminate the dark one with a flash and you'll be able to equalize both and capture them with the same settings in a single shot.

>>3067338
No. A neutral density filter would not help in any of your portraits if you don't know how light works.

>>3067338
If you shot raw and at or near base ISO you could easily have recovered those shadows in post.

...unless you have a Canon - then you'd be fucked.