If you shoot in RAW, you can upscale it in Photoshop to 16Mp.
Glad to hear that! Thanks!
How do I do that?
Does it make any difference if I were to save in 16bit tiff?
I understand that with a 8MP camera, I'll get decent 8R prints at 300dpi.
Will I still get decent result if I were to blow the picture up to 12"X18" printing at only 200dpi?
It makes a difference as CS interpolate the pixel to "create" the missing infomation, creating a seudo 16Mp photo. It is better then "enlarging" the pixel to fill up the space.
is this method of increasing the numbers of pixels/ inch helps?
no not really. not unless if you're the type to look at a banner from 30cm away for a few minutes to see if it helps or not. You MIGHT spot VERY VERY small differences there.
We have moved into the new century already, and bicubic and tricubic interpolation/extrapolation has long been in use for changing size. IIRC there's no option in PS for you to merely enlarge pixels anymore.
Thus, there's no real difference between using photoshop, or using the raw converter. They all use the same process.
but it sure makes most less techy people feel more at ease.
I understand that with a 8MP camera, I'll get decent 8R prints at 300dpi.
Will I still get decent result if I were to blow the picture up to 12"X18" printing at only 200dpi?