True if you look at it in isolation but if you put in context of the edit and the shots that follow it, it works because it expands in those other shots. Then we see the mushroom go up and the overall explosion darkens.
I mean this is no different than a lot of SFX shots where you do little tricks and put things together to give an illusion of continuity. So if you think of it as the peak of the cloud in slow motion because the following shots are either close ups of a wall of fire or a wide shot with the cloud fully in frame behind people watching. It starts to make more sense. Because obviously they cut different explosions together.
I admit I thought the explosion was slightly underwhelming when I first saw it. And since they hyped it up so much but after seeing the film several times now, and seeing the real footage - I quite like what they've done. Again, it's not 100% accurate. Maybe they could've got there with CGI but what we got isn't bad at all.
I mean this is no different than a lot of SFX shots where you do little tricks and put things together to give an illusion of continuity. So if you think of it as the peak of the cloud in slow motion because the following shots are either close ups of a wall of fire or a wide shot with the cloud fully in frame behind people watching. It starts to make more sense. Because obviously they cut different explosions together.
I admit I thought the explosion was slightly underwhelming when I first saw it. And since they hyped it up so much but after seeing the film several times now, and seeing the real footage - I quite like what they've done. Again, it's not 100% accurate. Maybe they could've got there with CGI but what we got isn't bad at all.