A few points to consider...
It depends on what kind of flexibility and quality you're looking for. There's a BIG difference between a near thousand dollar DSLR camera with interchangeable lenses and a cheapy pocket-size digital camera with a peep-hole lens. That's why there's different cameras-- they do different jobs and have far different capabilities...
First, the biggest difference is the "chip" or sensor. The larger the sensor, the better the camera. It isn't just about "megapixels" anymore... you can get 10-20 megapixels on a typical chip now, (one about roughly 1/4 inch square) but you're not going to get the same resolution or photo quality as you could from a chip with the same number of megapixels the size of a postage stamp or 35mm film negative. As far as megapixels go, it's a highly overrated thing, designed primarily to sell more expensive cameras to unsuspecting or unknowledgeable buyers... Megapixels basically dictate how much you can enlarge the photograph before it becomes "pixellated" or "grainy". It basically translates to the negative (film) size of old film cameras... for instance, you can enlarge a 35 mm to 10x14 pretty easily and still have a good quality print, but enlarging a picture taken with a 100 camera to even 8x10 usually results in a pretty grainy print. If you want super-high quality enlargements, you'd need super-large, super high resolution film or sensors... like those gorgeous posters of John Muir's work, taken with large-format cameras (using up to 3x5 film sizes or thereabouts) for top quality enlargements and super-dense images. SO, unless you intend to blow your photos up to poster size or put on the side of a milk truck, you really don't need more than 5-10 megapixels.
Factor number two, you need "quality glass". That's the big difference between cheapy film cameras and high-end professional quality film cameras. The larger the lens, and the higher quality it is, the better the image that it will send to the sensor, which makes a big difference in the final product. That's why "pinhole lens" cameras like the little 808 keychain cams have lower picture quality than cameras with larger lenses, even for equivalent chip sizes and resolutions... Basically, the larger the lens, the better the quality, up to a point... once you get up to DSLR size camera's, the difference isn't in the size, it's in the quality of the glass... and there's a BIG difference in a $150 lens of a given size, and a $1,000 lens of the same size... the difference is in the optical qualities of the glass itself. You'll see a distinct difference between the little cheapy point-n-shoot pocket cameras, and the mid-range "pro-sumer" models (look like a DSLR, but with non-removeable/non-interchangeable lenses) and the big true DSLRs (with interchangeable lenses). This is something you should bear in mind.
Thirdly is functionality. The cheaper the camera, the fewer functions it will have... and things like a good burst mode, and the ability to tinker with other settings, can be extremely useful and allow you to do thing with the camera you might not be able to do otherwise. For rocket photography, a good "burst mode" (which will take a sequence of pictures in very short order-- my Fuji Finepix S2000HD will take a burst of 33 pictures in about 3 seconds, at 5 mp. It's actually a 10 MP camera, but I normally run it on 5MP resolution setting anyway, to keep the file size down into the 1-2MB range... filesize depends on the photo composition, background, and light levels, and how "busy" the picture is... that's another drawback to unnecessarily high megapixel counts-- it leads to enormous file sizes for pictures that take up a LOT of room on your card and hard drive). Another important issue is the size of the buffer, or internal memory, that stores the photos from the instant they're taken (or in burst mode, the series of photos) from the time they're taken until they're written to the card as a data file. The larger and faster the buffer, the more "power" the camera has to take high resolution, rapid burst mode photos (particularly useful for launches). The speed of the card is the second variable in that equation-- the faster the card's "C-rating" (speed), the faster the camera can (generally speaking) write the files from the buffer to the card and be ready to take another photo. There can be a BIG difference in cameras based on the electronics, buffer size, programming, and card size on how fast the camera can take pictures... and cheaper is very rarely better...
The next thing to consider is, the sensor quality. If you're just taking rocket pics and other stuff like that in full daylight, a typical sensor can do that pretty well... the real difference in sensors becomes apparent in low-light conditions... a cheap sensor will have reduced low-light sensitivity and be "noisier" (not display blacks as "true black" but rather will have speckles of color in the dark portions of a photo) than a high quality sensor. Usually the larger the sensor, the noisier it tends to be (IIRC) so there's a tradeoff between size and quality. For typical rocketry use in full daylight, this might not be an issue for you. If you plan on doing night launch photography though, you might end up with some ugly shots with a cheap camera...
The other big issue is zoom... a cheap camera with a fixed lens (point-n-shoot pocket cameras) will have a lens of varying size and quality (anywhere from "pinhole" type lenses up to one the size of a quarter or thereabouts, depending on the camera) but usually they're a FIXED lens... these cameras can "zoom in" on a subject so it fills the screen, but this is done via DIGITAL zoom. What digital zoom does is simply "shave off" the information from the edges of the sensor and "zooms in" on only that part of the image striking the very center of the sensor. What this does is, in effect, reduce resolution and, more importantly, sensor size, thus making the image blurrier and less detailed, and of course making it much more susceptible to enlargement artifacts and other artifacts in processing and compression of the file. I turn the digital zoom completely off on my camera, as it basically just serves to degrade the image. OTOH, my camera has an excellent 15x OPTICAL zoom, which is zoom created BY THE LENS, meaning that the image is enlarged through the LENS and then that enlarged image is projected onto the FULL SENSOR, so that the image quality and resolution is maintained. This makes a huge difference in the final appearance of the pictures. IMHO, DIGITAL zoom is practically worthless if you want great looking shots... OPTICAL zoom is what you want. Of course, to get it, you have to get a camera with a zoom lens-- either a higher-end point-and-shoot with a motorized "extending lens" or a pro-sumer model (which is what the Fuji Finepix S2500HD is) to get the good buffer and functionality, while still keeping the cost reasonable.
My Fuji has been surpassed by later, newer models, but it does what I want and does it well... I'd recommend them to anybody, as it has the functionality while still being pretty intuitive to use and not requiring a steep learning curve to get great shots like a full-on DSLR usually does. It's also pretty reasonable on price-- not as cheap as a point-n-shoot pocket camera, but nowhere near the expense of a full-on DSLR either... and the functionality and better quality is something you'll have to pay for if you want good pictures.
Anyway, hope that gives you something to think about... I went through this entire learning curve a few years back, so I can understand how daunting it can be and why its so confusing...
Don't be afraid to go by your local electronics store (Fry's, Gregg, Best Buy, etc.) and actually "put hands" on camera's your thinking about buying-- it'll give you a feel for the settings and functionality that you just cannot get from reading about it on a website. Doesn't mean you have to necessarily buy it there, but hey, if you can get a deal... why not?
Later and good luck! OL JR
