I am a graduate student in image processing and computer vision, and I'd like to get into photography. I want to purchase a camera that isn't a black box, where I can experiment and learn about how and why. I also don't want to be buying another camera a year from now.
What is the suggestion for this case?
If you have the budget for it, I highly recommend a digital SLR camera in the mid-tier "prosumer" range. Currently, that's the Pentax K-5, Nikon D7000, Canon 60D, and similar. The brand isn't really important from this point of view, although you may want to compare lens lineups. Read this earlier answer on Are there disadvantages to a prosumer camera for a beginner, aside from cost? for details, but the basic point is that these models have controls designed to be used easily. They don't necessarily let you do much more than what you could do with a lower-end model, but what they do offer is dials and buttons that control every important option directly and individually. This is far superior than having the same things buried several clicks deep in a menu.
Of course, this assumes a non-trivial outlay of money. And you'll probably want to budget an equal amount for lenses (and a flash) within the first year or two. That may be more than you want to jump in with, but if you do end up being serious about photography, you will not regret it. And the higher initial investment may even save money overall (note: link is fictionalized).
If you do feel more comfortable starting at lower price point, a high-end point and shoot like the Canon S95 (or whatever is current) will give you a lot of flexibility and be a good starting point. But you probably won't be completely satisfied with it very long. On the other hand, a Canon P&S camera will let you run CHDK, an open source firmware hack which could open up a lot of possibilities in line with your field of image processing and computer vision — if you don't get enough of that in your day (and night, knowing grad students) job.
I was in the exact same situation a year ago, and I decided (without much reason, really) to go with the Canon EOS 550D. Until now, this turned out to be a good choice:
The last three points are rather important if you want to implement e.g. a SIGGRAPH paper and use your camera to generate the images.
Of course, none of the above are characteristically for the EOS 550D. I am merely given you a list of things you should watch out for when buying a camera.
I think that you need a camera where you could set the following;
These are the basic of the exposure triangle. This has been true for many years now. All modern DSLR will have this.
Other things to consider are:
If you get a camera with these capabilities you will be able to learn and experiment with. Then go from there.
Do not forget to buy an extra memory card. I still remember my vacation photos from Moscow being destroyed by a bad memory card. An extra battery is also good, but not crucial. Take this into consideration when calculating your budget.
Do not bother with megapixels for now, since you want to learn the technical bits of the programming. I would not bother with video recording capabilities, since this is not really necessary for photographing.
you can add Pentax K-r to your selection. I have its predecessor K-x and I am very satisfied with it. The price should be much better for K-r compared to K-5, but it has still many useful functions and settings. As I know you can also use standard AA NiMH batteries as a spare ones (cheaper than to buy second accu pack). And Pentax has very good support for old film camera lenses - the old Pentax AF lenses should work without problems and much older without AF with some limitations.
This could expand your possibilities to do some "creative experiments" without paying high amounts of money.
PS: do not know, how about other countries, but important thing for me is that I can spend more than 20% off the price if I order filters and other small equipment via Ebay directly from HongKong - especially genuine Hoya filters etc.
If you are serious about studying photography and going to pursue it half-to-full time, you'll rack up your 10,000 hours pretty quickly, and can easily outgrow an entry-level dSLR body that might be a better fit for a weekend hobbyist shooter starting out.
In this case, the best recommendation for a "value sweetspot" is typically going to be a mid-range "prosumer" camera (in Canon terms, an XXD model or 7D; in Nikon a D7x00 or D3x0 series), one generation back, used/refurbished.
You want the mid-tier/prosumer model main for the better hardware UI (more dedicated physical controls, reducing menu diving), expanded menus and functions, more robust bodies, and better fast-action features. You want one generation back used/refurbished, to get a camera that's depreciated into a more affordable range, but is still feature-rich compared to current models and is unlikely to be so old that the usable lifespan of the shutter box assembly in the camera could come into question.
Going by these criteria, I'd say look for a used/refurbished Canon 60D, or a used or refurbished Nikon D7000, since the current models (at the time of writing) are the 70D and D7100. Going factory refurbished will often be slightly more expensive than the used market, but the camera will have been thoroughly inspected/repaired by Canon/Nikon, and given a new-model warranty, and will still cost less than a brand new entry-level body kit.
