1DMkIV vs 5DIII or 1DX for Birds in Flight Which one ?

I have a 1DMKIV and 100-400V2 right now, and have been contemplating a switch or change up. I get more keepers than I did with my old 100-400, but still get quite a few out of ffocus shots.
So I was thinking either switching to a different lens(maybe a first gen 300 2.8) or switching to a different camera to get faster aquisition of birds and also improve my keepers.
What do you think would be the best move?

I own a 1dmk4, sold my 1dx and replaced it with the mk2.

No matter what body you own you will get quite a few OOF shots.

My 1dmk4 is still quite a capable camera, only the faster shutter and high ISO results of the 1dxmk2 put it in a class by itself.

If I were you I would rent/borrow a 1dx mk1 and try that and start from there.

The 300 is not usually a long enough reach for bif unless you add a teleconverter, so that slows it down slightly.

MajesticMomentsPhoto wrote in post #18137366
I own a 1dmk4, sold my 1dx and replaced it with the mk2.

No matter what body you own you will get quite a few OOF shots.

My 1dmk4 is still quite a capable camera, only the faster shutter and high ISO results of the 1dxmk2 put it in a class by itself.

If I were you I would rent/borrow a 1dx mk1 and try that and start from there.

The 300 is not usually a long enough reach for bif unless you add a teleconverter, so that slows it down slightly.

Interesting..... I have a 1D IV and am hoping to pick up a 1DX Mark 2 if one of my custom guitars sells. I'm wondering why you kept the 1D IV as your back up rather than your 1 DX Mark 1? I could guess but I'd rather hear it from you.

The return on investment was much higher on the 1dx. The 1dmk4 still delivers great images with good light AND the slight crop factor makes a difference once in a while.

Well today I drove down to Maryland the Conowingo Dam to photography the Eagles.
The moment I got there and I tried to focus on a gull I knew there was an issue with the1dx mk2 focusing and tracking BIFs

I tried all morning with dismal results the body just fails to adquire focus onsmall moving birds even as big as an eagle!

I had my 5dmk 4 with me which saved the day, I already called my contact at CPS and told them to expect me first thing tomorrow
Morning.

Totally frustrating

Could be a number of reasons that you're getting lots of OOFs. Could be your expectations are too high. Whatever the reason, a 5Dii will only get you 6 fps, a little too slow for BIFs, IMO. I would suspect that the 1DX has a better AF system than the 1Div, which would theoretically increase your odds.

Bsmooth wrote in post #18136527
I have a 1DMKIV and 100-400V2 right now, and have been contemplating a switch or change up. I get more keepers than I did with my old 100-400, but still get quite a few out of ffocus shots.
So I was thinking either switching to a different lens(maybe a first gen 300 2.8) or switching to a different camera to get faster aquisition of birds and also improve my keepers.
What do you think would be the best move?

5DIII and 1D4 are about equal in the AF dept.
The 100-400mm MkII is a focusing dream. You won't gain much with the 300mm prime.

The only way to really up the anti on the hardware side of things will be 1Dx2 or 5D4.

MajesticMomentsPhoto wrote in post #18166899
...

Totally frustrating

Ouch indeed

Expectations are the same as I have always had. Have been shooting BIF for many years so my experience is that when I use back button focus it should lock focus on on a bird,
Under the same circumstances i.e lighting conditions that other bodies have always been able to do. Specially when numerous other photogs are shooting with older bodies and are able to focus.

It wasn't lots of OOF shots unfortunately it was unable to lock focus on any birds past the 100 yd mark.

MajesticMomentsPhoto wrote in post #18167282
It wasn't lots of OOF shots unfortunately it was unable to lock focus on any birds past the 100 yd mark.

100 yards! C'mon, man! That's ridiculously too far for a 400mm. I've shot at conowingo with my100-400i and crop body. Beyond the power lines is too far.

And AF will only stay locked if you keep the dot o the bird.

Larry Johnson wrote in post #18167306
100 yards! C'mon, man! That's ridiculously too far for a 400mm. I've shot at conowingo with my100-400i and crop body. Beyond the power lines is too far.

And AF will only stay locked if you keep the dot o the bird.

I was using a Canon 600 f4 version 2 and the camera a 1 DX MK2 would not focus AT ALL, where the 5dMK4 would on the same lens. Been shooting for 35 years many of those professionally so I know exactly

how to focus...

I forgot to add in remark to your "tip" Af tracks beyond the range of the center point depending on your settings. You do NOT need to keep the center point on the bird for the AF system to track once Af has been adquired....

My mistake. I was thinking you were the OP with a 400mm. You have more experience than I do.

no worries, trust me i wish it were that simple! lol

Sorry to hear about the bad luck, mind if I ask how the action was at the dam? I'm planning my first trip down there this year, looking at the 2nd weekend in December right now.

It was slow, not many eagles there so far this year. I am returning next week.