7D ii or 5D iii for Birding

I understand that the 7D ii is a crop sensor while the 5D iii is a full frame, but other than that, which camera would be best for wildlife including bird photography? I would be using this for birds in flight so I want the camera that would do the best for auto focusing. The 7D ii has 65 cross types while the 5D iii has 61. Anybody tried both bodies with preference on one of the two?

I've had both and used both for BIF, so here's my take and my experience.

The 5D3 gives better IQ at higher ISOs. I did not find it to track very well, but that was when the new AF system came out and I may have had some settings wrong, although I don't think I did. Tracking well is very subjective and depends greatly on your situation. Tracking a wren at 30 yards in flight is a whole different ballgame from tracking a mallard at the same distance. Same principals, but bigger, more contrasty target.

As for the 7d2, it boils down to the copy you get. My first two were duds, the 3rd a money maker. IQ is very good, but I doubt, in my uses, I'll go very high on the ISO as I still think it suffers some. My keeper model has shown get promise as far as AF goes and the extra resolution I get should help me out in situations where my 1Dx/600II/2xIII have come up short. I can throw the same lens on the 7d2 with a 1.4 and have the same field of view ay 5.6, which should track much better.

That said, 600 on FF is awfully nice and really gives good background separation. Ultimately, depends on what you define as "BIF".

Are you saying that you received two malfunctioning 7d ii's and you had to exchange them? Is there a glitch in the first batch of cameras on the market?

Some people are reporting issues with the auto-focus on their new 7DII's. Other forums are reporting these issues as well. What we don't have is the people who report no problems so it's difficult to say how widespread the problem is. HuntersDad got two badly focusing copies. If you get a bad one you can return it to the vendor and take your chances with the next one or you can send it to Canon. Everyone that has chosen to send their camera in has been pleased with the returned performance.

As consumers, we should expect expensive equipment to arrive in excellent working order but as technical people, we know that doesn't always happen.

Having owned both, based on my experiences - the 5d3. The AF was quick and consistent - If I missed a shot 99.99% was my error. I have not had good luck so far with the 7d2 - on 3rd one as well - focus inconsistency. Now this opinion is just based on my own situation. In theory - the 7d2 would be the best with the crop factor, improved ISO and quick AF. Perhaps it would be best to rent each before you make a decision.

Thank you for the feedback, everyone. I just think that I would enjoy the extra zoom I would get out of my lenses with the crop factor. My 150-600 would be able to achieve a 900+ when using the 7Dii. I had to crop my bird shots with the 6D pretty heavily.

I happen to agree with you JM. For your application the 7DII (in good working order) is the best choice.

I agree 100%.

One of the problems is exactly what you say here -- the "problem" 7D2's speak with a very loud voice, and generally just a happy peep out of the 'good' 7D2's.

That factor has an effect on how people perceive the 7D2 and its focus issues. I was one of the 'lucky' buyers (maybe?) ... and have no issues at all. And I suspect many others on POTN find the same thing.

PLUS, we are on a photo forum and a whole lot of 7D2 buyers are not ... hard to make a case for 'a bad camera' as so many state, because we probably have a minority of the whole buyer market here.

But, it seems lots of 7D2 owners on POTN don't have issues, or have issues unrelated to the technology, but rather with the learning curve for the 7D2 - a pretty sophisticated piece of gear.

Back to the OP question: I have both 7D2 and 5DM3 ... both shoot birding well, but if I were choosing a camera, and birding was my main goal, I'd come down on the side of 7D2 - and primarily because both will track those birds and target very fast, but the crop factor will gain distance. It remains a tough choice and you won't go wrong with either one, and may come down to which lens you choose. If I was shooting birds AND a lot of general photography as well, then the 5DM3 will give you more all around flexibility. And, very tough to beat the IQ on the 5DM3 ... Hmmm, guess this post didn't help you much, did it? Except I'd worry less about the 7D2 focus complaints, and choose based on other factors, if that helps.

I have both and would pick the 7D2 for birding unless you are only shooting at dusk or something. Its easier to track something that's bigger in the viewfinder vs. just cropping in post. There are reports of focus issues, and that has been the case with about have the advanced DSLRs that have come out. I believe there are some that are defective and many more situations that people are so paranoid and/or are fiddling with the settings overly and getting bad results.

FF High ISO performance advantage is applicable only if your lens on your FF is long enough to match the focal length after 1.6 conversion.

I would rather use 7D mk II with 400mm lens (ISO 6400) without additional cropping than 5D mk III with same lens to be forced to crop the image in post to achieve the same FOV...

I have seen 2 7DmkII with focusing issues, it´s pretty scary :/
70D had some issues too.

Not the most helpful, but entertaining

https://www.youtube.co​m/watch?v=7H4uEXqCtI4

Unfortunately for small bird (1) the focal range is never enough so between the two choice above I would say Canon 7d Mark II that has even a better AF system.

1) Naturally I don't speaking about types of birds easy to be approached.