With respect SLR cameras pictures take up much more space them regular digital cameras. You may have 12 megapixels but you are limited to a 1600x1200 where a SLR can have up to 4064x2704 resolution. Its just a larger lens
First off, I'm using a
Cannon EOS Rebel Xsi 12.2MP D-SLR. I also have an ultra wide angle lens, stock lens, and a tilt action lens. So I'm very familiar with D-SLRs, memory storage, and camera lenses.
Secondly - Megapixels are a measurement of total pixels in an image - megapixels directly relate to resolution. So how do I have 12MP, while remaining at 1600x1200?? That is literally impossible. Let me explain why:
*4272 × 2848 is the resolution of an image taken in landscape by my 12.2MP DSLR - or if you do the math that's a total of 12,166,656 individual pixels.
*Following this math, we see that
1600x1200 is not 12 megapixels. 1600x1200 is in fact - 1,920,000 individual pixels, or translated into the easy measurement of 1.92 megapixels in laymen terms

.
*important* -- Resolution is determined by the camera sensor -
the lens has nothing to do with pixel count. A 15MP "point and shoot" will take nearly the same size (memory size) of photos as a 15MP DSLR. The only difference will be the level of color, saturation and light that is taken in by the lens affecting the (memory) size of the image in a very minor way.
Minor relative to the to amount of memory required to store 1600x1200, vs 4272 × 2848 JPEG images. It takes far, far more memory to store 12,000,000 pixels, than it takes to store 1,920,000. As simple math tells us that 12,000,000 > 1,920,00.
I would explain more in depth about how more colors/ranges of colors affect JPEG's size, but that would involve me explaining a JPEG codec

.
So yeah, I will stick with my original statement. - 32GB is a LARGE memory card in my mind. I will stick with my 16GB, and 8GB ($5-$10 ea.)

.