I've recently got my 7D II and Tamron 150-600 and now I'm looking for a tripod. The type of photography I want to work on is birds in flight photography.
What tripod specs should I be looking at, and what type of head? From looking around a bit I think a gimbal head will be good to allow me fast moving of the camera but without having to hold its weight.
My budget is about €500 (but flexible).
Your 7D Mark II plus Tamron 150-600mm lens weighs in at just under 7 pounds. Add a battery grip and a second battery and you're over 7 pounds. You must then factor in the use case and consider that the camera and lens will not be static, but in motion when tracking your subject. I would recommend that whatever tripod and head you choose be rated for at least twice the 7 pounds or so that you will be placing upon them. There are many tripods available that are rated in the 15-18 pound capacity range and those are the minimum I would consider. Also, don't forget that in addition to the weight of the camera and lens you should also include the weight of the head when looking at the tripod's weight rating.
When talking budget it is often hard to compare the same products in different countries. The current exchange rate means your stated budget of around 500 euros translates to about $550 US. The problem is that even when the same products are available in both places it doesn't necessarily follow that their prices always maintain the same ratio as the currencies do.
To get a decent gimbal head is going to easily eat up well over half your budget. To get the most out of the other half you're probably going to have to settle for a heavier aluminum, rather than a lighter carbon fiber, tripod. But you can get a good, functional pair for that budget or just a bit more. Something like the Induro GHB1 head and one of the lower end Manfrotto 190 sets of legs.
If you want to start out a little lower budget I recommend trying a good quality monopod. I've been using a Manfrotto 680B with a Manfrotto 234RC head for about 6 years. The head is a tilt only head, but that's all you need with a monopod. You can either lock the tilt adjustment in at an appropriate angle and tilt the entire monopod to pan up and down or you can back the adjusting knob off just enough that the head tilts up and down with a little resistance. To pan side-to-side you simply rotate the entire monopod. To rotate the lens and camera from landscape to portrait mode you use the tripod collar. The combo has worked well for me shooting outdoor sports and air shows and has stood up to brutal treatment and conditions with no problems whatsoever.
My cameras are lighter than yours (40D primary with a sigma 120-400) but birds in (high) flight and tripods rarely work together for me. This is partly because I'm too tall once the camera is tipped back.
For low-flying birds (as well as perched/static birds) I find a single locking control essential. And it's important that you support the camera/lens as close as possible to the centre of gravity. I've chosen a light ball head and mount via the lens bracket. Even unlocked you get quite a lot of steadying. Weight is an issue for me as I can be hiking all day with a full kit, so the light head (I have a slik and a manfrotto, there's no significant difference between them) is paired with manfrotto carbon legs. A head with separate pan/tip/tilt locks was infuriating especially because the hinges for tip and tilt were too far from the centre of gravity. I have only used a gimbal had with a scope. I liked it but not enough to buy one.
My spare tripod is an ancient aluminium thing, with the traditional single twist-arm lock. For moving subjects it gets in the way and takes my hand away from the camera controls (not just the trigger for which a cable release would be a solution).
You might choose a more upmarket head but I suggest that a single locking control (though you don't need to lock pan) and all pivots in a vertical line are essentials. Even if you're not expecting to walk far carrying your kit, this may change, so watch the weight. In heads you can get cheap and light, though they're obviously basic. In legs you have to pay to keep the weight down, so go for carbon upfront. I also don't find monopods much use for moving wildlife - with the head unlocked they move too much, with it locked you're too restricted. The exception is if you can clamp/strap them to something as in some hides.
for the head, have a look at the Beike Bk-45 gimbal Tripod Head. I've just bought one for use with my Canon 1Ds II and Sigma 120-330 F2.8. Much better (For this camera/lens combination) than my Manftotto pistol-grip ball head.
OK - it's not a Wimberley but then it's only a fraction of the price. Will be good enough for you to determine if a gimbal head is what your need and if you need a more expensive one.
