Do I need a Tripod for Landscape Photography
Much of what you pay for when purchasing a camera for landscape work, is its high dynamic range, low noise and high resolution. When hand holding, you are often forced to give up some of those features you have paid so much for.
ISO
When shooting at my camera's base ISO of 100, the images are so "clean", that even with some heavy duty processing, they rarely require noise reduction (I do use the default Lightroom color noise setting of 25). Even a modest increase to ISO 200 or 400 can introduce enough noise that your processing will require applying additional noise reduction during processing. If you are shooting JPG, instead of RAW, the camera's internal processor will boost the noise reduction filtering automatically. In either case, this leads to some loss of detail in the image.
Shutter Speed
The high resolution sensors of today, 42+ MPix in my case, make camera shake or movement more noticeable too. Even with image stabilization, 1/30 second using a 50mm lens is no guaranty of a blur free image. When I have shot a series of images at 50mm at different exposure lengths, I can often see noticeable differences in sharpness between moderately quick shutter times of 1/60 and 1/120 second. This is even with the benefit of my camera's excellent in camera image stabilization, which many DSLRs still lack.
I have certainly captured very sharp shots at 1/30 or even 1/15 of second hand held, but you better be prepared to take the same image 4 or 5 times and/or check your results before moving on, if you want to be confident that you captured a really sharp image.
Filters, Bracketing and Stacking
Often a polarizer lens is desirable to reduce reflections on water, glare on leaves or to deepen the sky. As the filter blocks some of the light, exposure times must lengthened or ISO must be raised to compensate. Sometimes you may want a longer exposure, on purpose, to smooth out water movement.
For some high dynamic scenes it may be desirable to bracket your images (this involves taking the same shot using under, over and normal exposures). The "overexposed" image(s) in your series will require additional exposure time to get the desired results. On a number of occasions I have done a hand held 3 shot bracket of -2EV (exposure value), 0EV and +2EV and found, when reviewing my images, that the +2EV shot was not as sharp as the others because the required additional exposure time was too long for me to capture a crisp shot. As an example, your camera might indicate 1/60 sec is the needed shutter speed for a normally exposed shot (you are thinking "that's no problem"), but that translates into the overexposed shot in the bracket requiring 1/15 sec, which is too long to handhold.
You may want to focus stack some images for maximum depth of focus. With your tripod holding your camera in position, it will be easier to set the focus between shots and when stacking your images later in Photoshop, there will not be any difficulties ensuring they line up.
Panoramas
Another advantage of a tripod is when creating a panorama by stitching images together. A handheld panorama is almost always a little crooked, requiring you to crop areas you were hoping to include in your finished image.
You are also likely to swivel your camera over a wider arc, potentially causing parallax errors that may result in "strange" artifacts in close by objects. If you take the time to level your tripod, you will have little, if any, "waste" that requires cropping. In addition, while the nodal position of your camera will not be perfect, it will certainly be better than you could hope to do handheld. I have owned fancy "nodal" add ons, but my experience has been, that unless the closest objects are less than a couple feet away, using a tripod is just as good.
When shooting in portrait mode, I am assuming you are using an L-bracket (below left) on your camera, which allows the camera to be sit directly above tripod center. If you don't own one, get one.
Issues to consider when selecting a tripod
Now that I have so convincingly persuaded you of the need for a tripod, "what tripod should I get?" you may ask. Price wise, tripods cover a wide gamut, from under $50 to over $1000. Here are some issues you may want to consider when making your selection. While many tripods, especially cheaper ones, come with a head, I am only going to address the actual tripod portion in this post.
How far am I going to walk or hike with the tripod?
Are you taking 10 mile hikes up a mountain or just a 50 foot stroll from your car on a scenic pullover? If you are planning on longer hikes or bike rides with your tripod, weight can be a significant factor in your choice. No one wants to carry a 10 pound tripod on a long hike. On the other hand, if you rarely stay very far from your car, saving an extra pound or two is not likely not be worth the tradeoffs lighter tripods come with. Some manufacturers will have both an aluminum and a carbon fiber version of a tripod. With the aluminum being somewhat cheaper, but the carbon being lighter. Many higher end tripod manufacturers only make their tripods in a carbon version.
If you carry the tripod long distances, you may also want to be able to strap it to or inside your backpack. In this case, the height of the tripod, when collapsed, may be an important consideration. Is it important that it fits in your suitcase?
How heavy is my camera and lens combination?
If you are using a heavy camera, or long telephoto lenses, the stability and weight capacity of the tripod become more important factors. Maybe you are going to take exposures that last several seconds. These scenarios require a tripod that can remain exceptional stable, in order to get consistently sharp results. If you have a large camera but don't shoot with long telephoto lens, the stability becomes less of a factor. Even though your camera/lens setup may fall well below the tripod's stated weight capacity, it is no guarantee of a tripod's abilities. The cheaper brand tripods, in particular, seem over inflating these claims. There is no "industry" standard for calculating these values. Also, what may work OK in an indoor studio, with no wind and a solid floor may be of little value with a breeze or sitting in a flowing creek. I have heard a number of professional state that the "maximum" tripod capacity should be at least double the weight of your heaviest camera/lens combination. I think that's at least a good place to start.
Where am I going to be taking pictures?
If you like the beach, salt water and sand can be very hard on a tripod. Salt water can quickly corrode metals and the fine sand can get into the log joints and stop them from operating smoothly. Are you going to be standing in a steam taking waterfall pictures? Some tripods advertise themselves as water and dust resistant and come with additional sealing to keep them operating in harsh conditions.
If you take pictures in colder climates, you may appreciate the foam grips that some tripod come with on the top leg segments. That sure beats grabbing a frozen aluminum pipe with your hands. Perhaps you have gloves on. Are the moving parts large enough to easily grip with your gloves?
Is it windy a lot of the time? You will benefit from a heavier more stable setup. When the wind picks up:
Remove the lens hood, as it adds more surface area for the wind to catch.
Longer or bigger lens give the wind more to grab on to.
Lower your tripod, if possible to create a smaller profile.
Telephoto lenses will magnify any vibrations or movements
Remove your camera strap. Buy a camera strap that can be quickly removed. Alternatively, wrap the strap around the tripod to keep it from flapping.
Use your body as a windbreak.
Some tripods have a hook in the center, allowing you to weigh them down, which can add stability. I leave my backpack on the ground and use a bungee cord (see below). I don't leave my bag dangling directly from the tripod hook, as this will introduce unwanted movement if the bag starts swinging around.
How tall or short do I want to go?
The majority of images I take are shot from a "normal" standing position. You are going to be most comfortable if your tripod can raise your camera to your natural eye level. This is going to different orf someone that is 6'2" than someone who is 5'2". For maximum stability, it is best if your tripod can reach the desired height without raising the center column (if your tripod has one). As the head you have mounted on your tripod and the camera body height itself will be raising your camera, and your eyes are not on top of your head, you can subtract around 9-10 inches from your height to find the ideal "minimum" tripod height for you. So, being 5'9", a tripod that can be raised to 5' (with the center column down) would be ideal. Note: even a tripod that is 3-4 inches below this "ideal" height will still provide a very comfortable position to work from.
Some interesting landscape images are taken very low to the ground. You can get your tripod down low by not extended the legs and by spreading them in a wider stance. If the tripod has a center column, this will often be the limiting factor in how low you can go. Tripods that do not have a center column or have the option to switch to a "short" column (sometimes included with the tripod) can usually get even lower. Some tripods have the option of reversing the center column and shoot upside down.
Some photographers advocate for tripods that have no center column. They do add extra weight, and they can get in the way of taking shots low to the ground. However, you will notice that all the tripods I own have center columns.
In my experience, when the center column lowered, the stability advantage of having no center column at all is negligible.
The additional weight is usually just a few ounces.
I rarely need to go lower than my tripod with column will allow.
Then why bother with the center column at all? Because, I take a surprisingly large number of images from overlooks where there are plants or other obstructions directly in front of me. Having the ability to raise the camera up an extra foot, or more, can make a real difference in seeing over the trees or bushes in front of you. The added height also gives you more setup latitude on steep terrain. While raising the column reduces stability, it's usually going to be better than hand holding your camera over your head.
Alternatively there are some columnless tripods that can go very high (over 6 feet) to give you this flexibility. The downside is they will be heavier and their folded length will be quite long, making them more awkward to travel or hike with.