Welcome aboard, Cristina!
Each evening, there will be photo opportunities with different backgrounds in the atrium lobby area. Families can simply arrive before or after dinner and have their photos taken, no reservations required. You might have to wait in line for just a few minutes, but it's a great opportunity to have formal or casual photos taken with your entire family.
Prices are always subject to change, but you can expect to pay around $19.95 for an 8x10 photo, or $12.95 for a 6x8 photo. Each day, photographers will be snapping pictures all around the ship and on Castaway Cay, and these photos will be on display at
Shutters each day, where you can purchase those prints or opt to buy a photo cd package. Again, prices are subject to change, but most likely you can expect to pay about $149 for a photo cd with 10 images or $249 for a photo cd with 20 images. There are unlimited photo cd's available as well, and those prices vary by length of cruise.
If you were thinking of setting up a private photo session with a Disney Photographer, this can be arranged onboard at Shutters, and this comes with a photography fee of about $85 plus the cost of the photos. Larger groups can arrange private photo sessions through Disney Cruise Line's Group Services. But, it sounds like you'd just like to get some professional portraits of your group of 8. Unless you'd like a different setting than the great backdrops and options they offer most evenings in the atrium, there probably won't be a reason to pre-arrange a photo session, Cristina. My family loves to take advantage of the complimentary photo sessions in the atrium and then we decide toward the end of the cruise which photos we'd like to purchase at Shutters.
I hope this helps as you plan your cruise! Let me know if you have other questions, as I'm happy to help!