David Watson, 74, made the images of the Corrie actresses', Jenny McAlpine and Kym Marsh, and Emmerdale's Natalie Robb, before sending them to their home addresses.
The shocking snaps left the women “sickened” and even lead Jenny to increase security at her home after she was left fearing attack.
Watson, from Daventry, has pleaded guilty to two counts of sending indecent imagines to Jenny, who plays Fizz Stape in the soap.
He also pleaded guilty to two charges of sending indecent images to Kym, who plays Michelle Connor, and Natalie, who plays Moira Barton in Emmerdale.
In some of the letters sent to the women he wrote notes, including one to Jenny, which read: “Jenny, I would love to see you like this”.
Watson, who found their addresses through an internet company who provided them for a fee, said he used his computer to make the images because he was bored.
He is set to be sentenced on 12 March.