I have some clips I have shot with my digital camera.
They are 640x480, 30 fps MOV files (probably in MJPEG format).

In the project settings, I have:
Frame rate: 30 fps
Format: 4:3 NTSC

I combine the clips in LW and then try to export the results.
Whether I select AVI or MOV in the Export options, the size option displays 1920x1080 and it can not be changed.
The resulting video is a large file in 1920x1080 resolution.
And since the aspect ration is different from the original, there are black borders at the left and right side of the picture.
This kind of result is un-usable.

Why does LW force conversion to larger size and different aspect ratio?
I want to keep the video in the original size and original aspect ratio.
Do I need some plug-in or additional codec or something?

I guess it would be possible to use some external program to reduce the size, but how can I get rid of the black borders?

Hello,
Try changing the export frame rate to 29.97 fps, and I believe you will then have other export size options available!
Ken

I had the same trouble with a larger format. I was being forced into 1920 x 1080. I did as Ken recommended but I also had to go change the project settings. The A/V synch was off, otherwise.

I tried that (I wonder what is the idea behind that?)

Now there were some options for the size, but there was no option for 640x480.
There were options 720x480 and 720x486. Both have aspect ratio different from the original 640x480.

For aspect ratio, there are options 4:3 (which would be correct for the source size), and 16:9.
I selected 4:3.

I exported as 720x480. The resulting file was smaller, "only" 722 MB instead of 23 GB.
(The original clips are 95 MB combined).

But the image quality is really poor. Obviously, the changes in size, aspect ratio and frame rate do cause loss of quality. Not good.

I don't know if it affects the whole process and how Lightworks sees it, but NTSC isn't 30fps, perhaps it should've also been imported at the 29.97, rather than just exported at that frame rate.

I have had better luck quality wise using "quicktime movie" export option, instead of the MOV selection. Also, make sure you choose the "configure" tab, and then select video settings, and then change the compressor quality from "medium" to "best" This will increase the file size, but will yield a much higher quality video on export.
Ken