Dramatic drop in file size - please help?

Question

My CR2 files of about 25MB are being reduced to about 1MB jpg's after going through ACR and PS CC and being saved. Sometimes I crop and sometimes I don't, this is not the reason.  Also I choose the save as max file size always. Where am I going wrong?
Mac OSX 10.6.8
PS CC
Using Bridge

Answer 1

The best reason for shooting RAW is that its very forgiving.  Its like having a peace of exposed film an exposure that does not get destroyed during development.  You can develop it over and over again.
The truth is there has not been a huge change in image size in your jpeg image unless you interpolated the image size during raw conversion.  If you do not interpolate the image size your RAW data is for  the same number of pixels as you jpeg image with the exception of some outer pixels which are only used to realize inner RGB color pixels in your RGB color image.   In fact there are more bytes required for the RGB image.  For 8bit RGB image have three 8bit values for each pixels. 8bits for red 8 for green and 8 for blue. So each pixel requires 24bits, 3 bytes. Raw pixels have a single 12 or 14bit value for a single color Red or green or blue. For most digital sensors and there are twice as many green pixels as there are red and blue pixels. 
The quality of each pixels varies with sensor exposure lighting etc.   There is also a quality setting for jpeg from 0 to 12 which influences how compression is performed.  High values in the 10 to 12 range produce  larger files and when the image is encoded into a jpeg file.  When a jpeg file is decoded the image quality is close to the image that was encoded with a high quality value jpeg setting  but its not exactly the same. Some image quality is lost. You will be hard press to see any difference in print quality at quality 10 and 12.  Quality 10 jpeg file are quite a bit smaller then the quality 12 files.
It is not a good idea to work on an image using jpeg image format with repeated edit sessions. For image quality will drop a little with each edit session.  If you edit in a single edit session you can save the image over and over again in jpeg format without loosing a much image quality it the same as encoding the image once in jpeg.   You loose quality when you use many edit session.  Each session generate a new generation of the jpeg image. Each additional edit session causes a jpeg format decode and a jpeg encode for the save one or hundreds of saves.  The original edit session if done through ACR did not have any jpeg decode. It had a RAW conversion that was later save and encoded in Jpeg format.
Its the sequence decode encode decode encoed  the cause quality lose each edit session only has a single decode duing open.