A little later than planned, I'm back! Mingling went on longer than expected ...
OK, to business: this is probably one of those situations that would be so much easier to figure out on-site, but based on what you've written above and what I'm seeing in the test footage, here are my more complete observations (if you want me to annotate screenshots to make these comments easier to follow, let me know):
I still found things going out of focus, and the scene very dark.
But the f/stop wasn't that high, so that is probably the issue.
In almost every shot, it definitely looks to me like the front of the ship is too close to the lens, regardless of whether it's moving left-to-right (nearest element permanently out-of-focus), or moving towards/away from the lens (nearest element goes/starts out-of-focus but is more in-focus at a distance. According to the lens specs, it
should be able to keep focus at as little as 20cm - but the f/stop will dictate how much of the model is in focus in any one frame.
In some of the later scenes, especially where the ship is moving away from the camera, I can see the in-focus region shifting. This suggests that you're using an f/stop that is too large for the size of the model
or that you're (auto?)focusing on nearest point, and losing sharpness at the back in favour of an in-focus foreground that doesn't exist. That can be fixed by manual focusing at (or just behind) the hyperfocal point.
All of the above takes us back to the equation between focal length, f/stop and light: if you're using a
short focal length
(which 24mm is) and a
wide aperture
(which f/3.5 is, if you're not stopping down from that) and you're focusing at 20-30cm, you'll have to add a lot more light to the parts of the model further away from the camera: the inverse square law of light is exaggerated at close distances like these: if you light the model homogeneously, the camera will only see 1/4 the light on those parts at 40cm compared to what it sees on the parts at 20cm
(I don't remember you ever citing the dimensions of the model, but I reckon it's about 30cm diameter? )
Using a longer lens, and by extension positioning the camera further away will reduce the relative distance between the front and rear of the model, making it easier to light. As a rule, longer/telephoto lenses (can) make the subject seem smaller by pulling the background forward to dwarf/dominate the subject, but as you don't have a background, this doesn't apply. You do, however, risk flattening the perspective of the ship ... so you'll be messing around with lighting again to restore that depth of field.
Having said that ...
in order to make the model appear large in size
I'm actually wanting to get the entire ship in the focus range to give the illusion of size.
... this is a whole different challenge. Against a monochrome background, it's impossible to create an impression of either size or speed. You can see the problem in (millions of) aircraft spotter videos: turn off the sound and unless there are clouds in the background or trees at the bottom of the image, all you're left with is a plane in a frame - an Antonov 225 looks no more exciting than a Cessna 225.
With an "emptiness of space" background, you'll have to engineer the concept of size in some other way.
For the various Star Wars models, they used visible "human" figures for the smaller craft so that we (the audience) could relate to the size of vehicle; and for the larger fleet, they added lights - lots of lights - to re-create how we Earthlings recognise the difference in size between a skyscraper and a family home. For one of the bigger fleet models, they used 100 000 pinpoint LEDs to create the effect ... before having to come up with another technique for Vader's even bigger star destroyer!
It probably too late for you now, but I can count only 12? points of light on your ship - any chance you can increase that?
If not, the next best technique is ... lighting! Use the inverse square law to shoot an extreme close-up and deliberately underexpose most of the ship, so that as it crosses our field of view, it seems to go on "forever" as the rear parts emerge from the shadows. You can enhance that impression with low-frequency "big-n-heavy" sounds. It might be enough to put a lot of effort into getting that as perfect as possible for the first/establishing shot showing the ship after launch; once the audience has been appropriately "calibrated" you should be able to get away with more subtle suggestions in subsequent shots.
120fps for real time slow motion instead of pictures.
Not sure what to suggest in this respect. All of my animation experience (which isn't much, and was a long time ago) was based on the
model moving, not the camera; and in more recent times, when dabbling in timelapse sequences, the traditional advice was to make sure that a
slow enough shutter speed was used to ensure that the image was very slightly blurred, as it made for a smoother/more realistic shot when played back at 24fps. But now, with 4k video played at 60fps ... maybe the rules have changed?
I was doing research and the slider that Derek used was over $3,000 mixed with the Dragonframe software.
There are loads of YouTube videos showing how to make sliders for less than $100, using a Raspberry Pi or Arduino as a step controller. It's something on my To Do list ...
Are you working on this day and night, every waking moment - or is it mostly at weekends? If you let me know the dimensions of the ship, I might play around with focal lengths and apertures during the week and see if I can come up with some reference values.
