Help creating zip files with 50 files in each
Here's a quick and dirty BASH script.

Assumptions: All of your photos are in a folder, and there's nothing else in this folder.

#!/bin/bash
zip_count=0
files_zipped=0
folder_number=1
div=50
numfiles=(*)
numfiles=${#numfiles[@]}

mkdir zips

for file in *
do

  file_list="$file_list \"$file\""
  let "zip_count=zip_count+1"
  let "files_zipped=files_zipped+1"

  if [ "$files_zipped" -eq "$numfiles" ]; then
    echo "Final ZIP..."
    echo $file_list | xargs zip -9 zips/$folder_number.zip
  fi

  if [ "$zip_count" -eq "$div" ]; then
    echo "Next Zip..."
    echo $file_list | xargs zip zips/$folder_number.zip
    let "folder_number=folder_number+1"
    zip_count=0
    file_list=""
  fi

done


You can download it here

Once you've downloaded it:


Open Terminal.app and change to the directory with your photos in it e.g. cd /path/to/photos
Run the commmand bash ~/Downloads/zip50.sh (assuming you've downloaded the script to your downloads folder.)
A new folder called "zips" will be created in the folder with your photos.