What is the color space (color mode +profile) in the Illustrator file?
What is the color output space in the PDF?
Which file type did you save the Illustrator file to place in InDesign?
Why did you use InDesign to create a PDF and why did you not save as PDF from Illustrator directly?
So, upon investigating, I realized that my color space in Illustrator was RGB... Damn... I must have overlooked that... When I convert (in Illustrator) to CMYK, I get those strange colors again.
When I export to PDF, the Output is "no color conversion", so it's not being converted to CMYK yet...
Plus, I just linked the AI files in Indesign when I placed them in there.
So, Indesign must be converting the file to CMYK? And that's why the colors change once I convert to PDF? What do you think?
Also, I used InDesign to place the files so that I could create a 2-page pdf easily that the printer could work with. I had a 4-up handbills page in there that I was planning on printing as well.
So, if this looks best in RGB, what do you think about me sending an RGB file to the printer and then printing it that way? I've been told that RGB is no good for printing, but I've also read otherwise as well...
If you want to print it in CMYK, I would recommend to use and create it in Illustrator in CMYK. (If it would be a photo in Photoshop, I would recommend to save as RGB image.)
Every RGB drawing will change if converted to CMYK, so you have to live with it or adjust your colors in Illustrator in CMYK mode.
You can save your image in Illustrator as PDF file. If you don't make changes or add anything in InDesign, you can save it in Illustrator as PDF. Ask your printer for the specifications.
You should only send it to the printer in RGB, if he requires so. BTW RGB cannot come upon paper, so you have to expect a change until there anyway.