Calibrate vs Densify Image Scale

What is the difference between the image scale for the calibrate step vs. the densify step. I used 1/1 for my calibrate option for a project w/13,000 images. When I run the densify step, if I chose 1/2 image scale, will I lose quality? Should I use 1/1 to get the best resolution and quality? I’m concerned about the possibility of it failing and not being able to run. I have a desktop w/1TB SSD w/backup 6TB HDD, i9-10980XE CPU @ 3GHz, 128GB ram, and Nvidia T1000 8GB.