I was and still am a big fan of Jerry Uelsmann, as well as Maggie Taylor, In 1983 I started my journey of photomontage on a Lisle Camera, I am pretty sure very few
have ever heard of this unit as if I am correct there were less than 6 made worldwide, Basically it was an x/y bubble memory layout computer driving an overhead front light and backlight camera with a back room with a rotating vacuum back with cropping blades that we could move with 0001 th inch tolerance. We used this machine to position our images in a composite, somewhat like Jerry's set-up of over 15 enlargers in a row, we would us compression and expansion pano lith masks to allow smooth blends of images together . Our film source was usually 16 x 20 E6 film which would then be sent to the separation houses, or we worked on BW or Colour negative film depending what the job required. I spent the first tortuous 9 months trying to wrap my mind around how to make this magic happen, one day it clicked and it was then my job to teach others which it seemed always took 9 months. My first year of college we were assigned to photograph two images and blend them together as one, basically it boiled down to finding a common time for both images (10seconds) and then overlap each image on two enlargers using the same easel and the red filter to position and then come from one side for one image with a card and then the second image the second side, making sure you timed it so that you went end to end within the 10 seconds.
I use vibration machines to create chokes and spreads with pano lith which kind of did the same thing which would help us blend the two images, I kind of remember this Mantra
Visualize you design from the top image to the bottom image and use the upper image to create the lower image masks.
confusing as hell