I take a lot of macro pictures, so using a tripod can be very inconvenient at times. And when I'm so close to an insect I find my hands shaking a lot even though I try to be as stable as possible. So I set the shutter speed pretty high (1/400-1/1000) that way I can just snap away and the pictures don't come out blurry. Are there any disadvantages to this? I know I get a lot less light this way, but I set my ISO to 6400 which helps a lot.
No is the answer to the headline question:
- A tripod gives you stability. As long as it is sturdy and triggered remotely, so that you do not shake the tripod, you are extremely likely to get the shot without blur.
- A high shutter-speed increases your chances of not moving during the exposure because you have less time to shake during 1/1000s than during 1/100s, for example.
For macro work a tripod is highly recommended because the DOF is so shallow. Even your tiny movements may change the plane of focus and cause problems. That is why people often use it in combination with a macro-rail which lets the camera move back-and-forth in a precise and controlled matter.
To answer your question: Yes, it does.
But I think you're using a wrong problem-solving approach. Increasing the ISO value to 6400 introduces a lot of noise into your image and you're losing details.
Maybe you better buy a monopod to slightly support your hand and reduce hand shaking, while still being lightweight and easy to use.
By using a high ISO value, you add much noise to your picture, which can be very disturbing, especially in macro pictures. In a dark environment there is no real way to get away from a tripod, but while capturing images in a bright environment high shutter speed will do the trick. There are no disadvantages by using a higher shutter speed in a bright environment (if you keep thee ISO value low). Depending on what camera and lens you use, you might want to take advantage of features like Nikon's VR to keep your images still, even with lower shutter speed. I managed to take a close up picture with a 108mm lens with a shutter speed of 1/13sec free hand with the help of VR and it is mostly sharp.
A rule of thumb is to keep your shutter speed faster than 1/f, where f is the focal length of your lens in mm. For example, when shooting at 200 mm, keep the shutter speed 1/200s or faster. If you are using a crop sensor, then multiply the denominator by your crop factor (e.g. ~1/300s or faster for 1.5x crop).
If you have image stabilization, you can keep the shutter open for as much as 3-4 stops more. Thus, 1/200s would become 1/30s, though your mileage will vary based on the lens IS system and how shaky you yourself are.
If you do not have a tripod, you can open up the aperture (shrinks DOF) or increase ISO (increases noise). Sometimes these schemes are useful (e.g. ISO 200 -> 400 won't make much difference), but if you don't have a lot of light to start with, they can negatively impact your photo.
A tripod eliminates all blur due to camera shake (if it is a sturdy and well positioned tripod). Some people are as paranoid as to flip the mirror before taking the photo, in cases where the camera has this feature.
With macro photography a tripod is essential. A high shutter speed will certainly reduce blur caused by camera movement. Ditto for subject movement. That's fine. But it doesn't matter if your focus is sharp if it is focused on the wrong thing. The key constraint of macro photography is the very narrow depth of focus, sometimes a matter of millimeters. To accurately place your plane of focus you really need to slow down, use a tripod, zoom in one your viewfinder and get the focus exactly where you want it.
Of course, that is the ideal, in a studio setting. If you are dealing with live insects, that are moving, perhaps rapidly, then you may need to compromise. For example, I find that using a ring flash at f/11 works well shooting hand-held. 1) The flash freezes subject motion. 2) The smaller aperture gives greater depth of field making the focus more tolerant. 3) And the inverse-square fall-off of the flash illumination knocks out the background which would otherwise be distracting at f/11.
Depending on the situation, high shutter speeds may compensate for lack of physical support for the camera. However, this is not a complete solution, and is not a substitute for a tripod in macro photography.
- The need to use a high ISO sensitivity leads to high noise and loss of detail.
- The lens usually needs to be wide open or nearly wide open, making it difficult to achieve optimal sharpness with the lens and making it difficult to achieve deep depth of field. This is especially important with macro photography, where the depth of field is usually very shallow.
- If the subject permits, a tripod can enable very long exposures at lower ISO sensitivity levels and with the lens stopped down to the optimal aperture. If the exposure is long enough (typically one second or longer), dark-frame subtraction can be used, further reducing noise without losing detail.