Bill, Can you explain your comment, ”Cropping also reduces depth of field some,…” I don’t understand how that works.
How do you get two birds in focus at one time?
- Thread starter Kathy#1
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I guess we all assumed he meant increasing the f number?
The assumption is we are going to view the cropped image at the same size as the uncropped. Meaning everything in the cropped version, including the blur, will be magnified. Check out a DOF calculator and keep all settings the same except switch from full frame to crop camera.
It's kind of like how we can't tell the Genie we wish for more wishes. For example we can't take a macro shot from further away because it has better DOF hoping to crop later to make the flower bigger in the frame.
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This is sometimes confusing when they say "single point focus." Even though they say single point, the whole plane parallel to the sensor at that distance from the sensor should be in sharp focus, not just that one point. Of course lens makers can't get it perfect but that is the goal. Everything parallel to the sensor the same distance as that single point is in focus. So if you were straight on the birds so they were both pretty parallel to the sensor, then single point focus on one bird would have the other one be on the same plane of sharp focus.
Since you were angled, if you imagine a plane projecting out from the sensor parallel to the sensor at the focus distance of the closer bird, that puts the second bird behind the plane of sharp focus. If you move right you hit a spot where both birds lie on that same plane.
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As Dan posted above, the camera can only focus to one distance regardless of how many subjects are in the frame no matter how sophisticated the AF system. If you can arrange the scene (position yourself) so the distance to one subject is the same or very close to the distance to the other subject(s) then you can get both in decent if not perfect focus. So yes, leaving Bird subject detection enabled is usually the best bet but that will still just detect one of the birds and hopefully others are pretty much the same distance from the camera.
Depth of Field (DoF) is determined by the aperture you set for your lens (f/stop) and as you stop down you increase the range of distances that will appear sharp in the image so by stopping down the lens one or a couple of stops if the light allows you get more margin for multiple subjects that aren't exactly the same distance from your camera but there's only so far you can practically take this. IOW, two Swallows on a fence with only a few inches distance difference between the the eye of one and the eye of the other is usually manageable especially if you reposition slightly so you're more perpendicular to the fence (keeping the distance closer to the same). But a couple or many subjects at greatly different distances when shot with long focal length lenses (relatively high magnification) or in macro situations (very high magnification by working so close) is tough and often stopping down a few stops still doesn't bring enough DoF to keep everything sharp. There are advanced techniques like focus stacking where multiple images each focused individually are combined to create one sharp image can be used but those are tougher situations.
Bottom line, when shooting wildlife with long focal length lenses things get tougher as you include more subjects assuming you want to keep all of their eyes sharp. When light allows, a bit of stopping down to increase DoF can help and setting up your shot so more or all of your subjects are at or very close to the same distance can help a ton but of course that's not always possible.
Yes should have been more careful with terminology. I meant increase aperture setting i.e. f-stop.
BlackRockArt
Well-known member
Thanks Kathy, I would not be too worried with these two at this state; usually I would wait until the lover birds get going to take pictures.
Enjoy & have fun.
Oliver
David Berry
🇦🇺 Australia 🦘
Example of decreased aperture resulting in increased depth of field:
My quick fix to include multiple birds in focus is to decrease the lens's aperture.
… David
- focal length = 500 mm
- camera–subject distance = 12 metres
- aperture = f/7.1
- depth of field = 230 mm
My quick fix to include multiple birds in focus is to decrease the lens's aperture.
… David
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Amit
New member
Strange, from here it looks like both birds on the same surface (Z axis), but the camera position looks a bit not in parallel with the fence... maybe that's the reason.. you can also see it by the line of the fence ... you where on the left side with angle to the fence (rather than 90)....
Thank you for this detailed explanation!
Thank you, this is very helpful!
HaHa! This is a solution. In trying to photograph my Tree Swallows I am probably interrupting their courting.
Thank you for the examples! These images are stunning! I especially like that you captured the birds interacting with each other.