Selection of camera for scientific experiment purpose?
The problem is:
There's a transparent tube of 12 mm diameter through which air - water mixture is flowing at a velocity of 3 m/s. The camera is kept at a distance of 4 feet from the tube. The length of the tube which is to be captured is 120 mm. The tube will be illuminated sufficiently. What is the resolution I will get if I use a NIKON DSLR 7000 camera with ISO 100 speed? Will it be necessary to take photos with a higher ISO speed? Also please tell me what shutter speed, frame rate and f/ number should I select to get maximum number of pixels in my image? Please note that only still images will be taken for a period of 60 to 90 seconds.
It will be very kind of you if you can explain to me in detail the basis of your judgement.
No one, and I mean no one can tell you anything without actually being there. You're going to have to experiment and find out - This can't be done by remote - you have to be there.
By the way settings, including ISO, have nothing to do with pixel count.
Exposure settings are not definite. It depends on the conditions of lighting at that place and at that time. Without being there, no one can tell you exactly what settings to use. The best is to set the camera to Auto mode and hope it gets sufficiently what you are after. With well lighted scenes, ISO 100 is the best.
Resolution doesn't change unless you raise or lower it in the camera. Set camera to highest resolution (megapixels) for best results. If you meant picture quality, then the above paragraph is all about it.
12x120mm 4ft away isn't very much. That I can see right now. If it is absolutely necessary to take the whole length then perhaps using dyed water will show up better on a thin tube. If water has to be clear, maybe you can use a wider diameter tube. Without knowing exactly what you are after with the experiment, I can't suggest any more.
You misunderstand how camera settings work.
To shoot at ISO 100, there has to be enough light to do so. If you want to see the mixture clearly (if possible at that velocity), you will need the fastest shutter speed available on the camera-1/8000 second-which also means you will need plenty of light. The aperture (f/number) can be set low to compensate. Higher ISO will increase image noise, making it more difficult to see what you're shooting.
The D7000 has a built-in intervalometer, which you can set between 60 to 90 seconds. At the other end, you can use high continuous drive mode (CH) to shoot up to 6 shots per second. Using a Class 10 or better memory card will allow you to take more shots at high speed (or longer video).
Resolution is dependent only on the size (QUAL) of the image file you choose. It is best to just use the maximum size available-16.2 MP for the D7000. Resolution is *not affected* by frame rate nor exposure settings.
120mm at 4 feet away is a field of view of about five degrees, which works out to a lens focal length of about 240 mm. This can be covered by a 70-300mm lens. A 55-200mm or 70-200mm lens will shoot a little wider. Most other lenses (especially the common 18-55mm) will not have enough zoom power.
tl;dnr Use a lot of light (high wattage lamps), and get a long lens.
If the mixture is flowing at 3, 000mm/sec, then at a shutter speed of 1/1000th second it will have moved 3mm. Is that too much motion blur, or would the kind of detail you need to see be clear enough?
At ISO 100 and f5 you need a light source as bright as direct, noon-time sunlight for 1/1000 sec to be the correct shutter speed.
At f2.8 you could use 1/3000 sec, to obtain 1mm of motion blur.
You might achieve faster exposure speeds with flash.
Here is the flash duration for a Nikon SB600:
1/900 sec. At M1/1 (full) output; 1/1600 sec. At M1/2 output; 1/3400 sec. At M1/4 output; 1/6600 sec. At M1/8 output; 1/11100 sec. At M1/16 output; 1/20000 sec. At M1/32 output; 1/25000 sec. At M1/64 output