Help on super-tele focus

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eleff
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p.1 #1 · Help on super-tele focus

I just bought a canon 400/F4 and just started to shoot eagles.

Depth of field is fairly thin.

What F-stop is generally used (i.e., when should I bump up the ISO instead of opening up the lens)?

I have a 5D. I am currently only center focusing rather thatn using all the points.

What part of the bird does one focus on?

Scott

Jan 22, 2008 at 05:45 PM

StarDog
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p.1 #2 · Help on super-tele focus

Scott, google a: "DOF Chart"It will blow your mind how shallow a 400 is at 5.6
Try f8 and almost always focus on the eye. That is my rule but it can be broken. Distance is a big thing on DOF - If you areclose to the birds stop down more. Bob

Jan 22, 2008 at 06:29 PM

eleff
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p.1 #3 · Help on super-tele focus

Thanks. That explained a lot about why I thought the lens with a 1.4 extender was soft. The DOF even a F8 and 50 feet drops considerably from 400mm to 560mm. My moon shots last night were sharp with or without the extender (beyond the hyperfocal distance).

How fast does a gliding bird fly? Or equivalently, what is the slowest shutter speed I can use (which then, at F8 and ambient light determines the ISO). I can, in theory, hand hold around 1/100 sec with IS.

Jan 22, 2008 at 07:57 PM

Chris Willis
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p.1 #4 · Help on super-tele focus

I use the same rule of thumb - f8 -- but I also break it pretty regularly. It will help you to play around with a DOF calculator and see how subject distance and f-stop interact to influence the depth of field. Obviously, the closer you are, the shallower the DOF, so greater need to stop down. But when the light gets down low, I open the lens up more, generally feeling that once I get to ISO800 (on my 40D), I don't want to go higher if I can avoid it. But again, that is dependent on distance, because if the bird is filling a significant portion of the frame, you can run noise reduction without affecting the overall image very much. Having the subject further away and needing to crop, the noise and NR software will impair the image more, but then again you can also open the aperture more freely becuase the DOF will be greater.

That is kind of a roundabout answer, but mainly I shoot f8 if I can and try to focus on the bird's eye. That is the baseline and I vary it based on conditions.

Here is the DOF calculator link:
http://www.dofmaster.com/dofjs.html

Chris
www.pbase.com/cwillis

Jan 22, 2008 at 07:59 PM

Chris Willis
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p.1 #5 · Help on super-tele focus

Our posts just crossed. My answer on flying birds is that I try to get the shutter speed to be 1/1000 or faster, even for large birds. Your ability to handhold and IS will not enter into the equation -- those shutter speeds are entirely too slow for anything moving at all, much less any kind of flying bird.

Chris

Jan 22, 2008 at 08:02 PM

mark fadely
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p.1 #6 · Help on super-tele focus

Hey Scott, congrats on the super combo of 5D and 400. Nice thing about the 5D is you can shoot all the way up to iso1600 and not worry about noise. You should be able to get great shutter speeds most of the time. I shoot my 5D on the finest jpg setting so that if I have a heavy crop the image can take it without degrading so much. Croppability is a very nice feature of the 5D's 12.8mp images. It is full frame so you're losing the 1.3x or 1.6x "magnification" of the cropped sensors, but you gain a significant amount of that loss back in the higher quality more croppable image though. You can put a 1.4 extender on that lens too. I love shooting wildlife with my 5D even though I'm usually using my 1dmk2 because it's autofocus is better for action. The autofocus on the 5D is not too far behind it though.

I shoot my 400 5.6 wide open most of the time. The DOF is never a problem unless it's a real small bird at close range, and even then you have a chance of really getting a killer shot if the autofocus picks up the right spot on the bird. Of course if you shoot at f4 the DOF is going to be that much thinner.

I agree with Chris that most bird-in-flight shots should be at 1/1000th or higher, but sometimes you want to try some artistic effects like panning and such. So experiment and see how it goes.

I always use center point on my 5D and 1dmk2. If the bird is in-flight I just try to keep the focus spot on the bird. That's hard enough for me. If the bird is stationary then I think about its eyes or other focal points.

Edited on Jan 22, 2008 at 11:17 PM

Jan 22, 2008 at 09:53 PM


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