500mm vs 600mm

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Ken Miracle said:
The other issue in your example would be a shorter focal length already at infinity with subject at 50 feet and background 20 feet behind that the depth of field for a Z 50 mm f/1.8 or Z14-30 f/4 is signficantly different than a Z800 f/6.3 pf or even a Z600 f/6.3 .... those are radical differences of course. There is also far less of a "magnification" factor so the perception of size difference between the subject and background is quite different.

What I need for birds and great bokeh is an 800mm Plena ... That would be one heavy in the hand and pocket book lens :)
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I think if you framed the foreground subject the same the dof would be the same, I was just noticing that the relative size of the background object would increase as the distance from camera to subject increased. If the background was blurred it would give the impression of better background blur because the blur spot would be larger relative to the foreground.
 
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bleirer said:
I think if you framed the foreground subject the same the dof would be the same, I was just noticing that the relative size of the background object would increase as the distance from camera to subject increased. If the background was blurred it would give the impression of better background blur because the blur spot would be larger relative to the foreground.
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@Steve has a great discussion starting on page 130 of his "Secrets to Exposure and Metering for Nikon" Book.

On pages 136 and 137 he has a good discussion on depth of field distribution related to lens focal length.

One of my favorite quotes from this book "
"Again, these are gross generalizations just to give you an idea of how distance, focal length, and F/Stop can affect the distribution of sharpness (DoF) in your images. There are limitless combinations of course, so it’s impossible for me to put every scenario in this book."
 
Ken Miracle said:
@Steve has a great discussion starting on page 130 of his "Secrets to Exposure and Metering for Nikon" Book.

On pages 136 and 137 he has a good discussion on depth of field distribution related to lens focal length.

One of my favorite quotes from this book "
"Again, these are gross generalizations just to give you an idea of how distance, focal length, and F/Stop can affect the distribution of sharpness (DoF) in your images. There are limitless combinations of course, so it’s impossible for me to put every scenario in this book."
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What were some of the generalizations?
 
Ken Miracle said:
Related to impact of focal length on depth of field and the nature of that field of focus. Best if you read it. At this point I would not feel comfortable in trying to copy and share anymore from the book unless @Steve authorized it or did it.
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I was just wondering if you quoted him because you thought that his generalizations refuted what I was saying, or did it support it? I agree it's complicated and I surely don't understand all of it.
 
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bleirer said:
I was just wondering if you quoted him because you thought that his generalizations refuted what I was saying, or did it support it? I agree it's complicated and I surely don't understand all of it.
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It boils down to the focal length of the lens at the same distance from the subject and the same aperture creates a different depth of field in front of and behind the focal plane. It can impact both foreground and background "sharpness" etc. I never have a concern with sharing @Steve free video etc. but just not comfortable with sharing from the books he sells. His books are not expensive and great resources.
 
Ken Miracle said:
It boils down to the focal length of the lens at the same distance from the subject and the same aperture creates a different depth of field in front of and behind the focal plane. It can impact both foreground and background "sharpness" etc. I never have a concern with sharing @Steve free video etc. but just not comfortable with sharing from the books he sells. His books are not expensive and great resources.
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His books are a great value I agree. I was talking more about the way the relative size of the background changes as the physical distance changes, no matter what focal length. not staying at the same distance and swapping lenses. I wasn't talking about dof.
 
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bleirer said:
His books are a great value I agree. I was talking more about the way the relative size of the background changes as the physical distance changes, no matter what focal length. not staying at the same distance and swapping lenses. I wasn't talking about dof.
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why @Steve says the issue is complex but the focal length has a significant impact on DOF and "bokeh" in front and behind the focal plane. The other factors also kick in we have noted distance from subject to those backgrounds and fore grounds and distance from the lens to the subject. For instance with my Z 800 pf at the minimum focal distance of 16.5 feet or slightly over and wide open at f/6.3 a small humminbird on quartering in the frame will only have half or less of the bird in focus and the foreground and background will be out of focus. With a Z24-120 at f/4 wide open at the same distance at 24mm the whole bird will be in focus but also more of the foreground and background the depth of field and focus clarity of the foreground and background will decrease as I would change the focal distance to 120 but nothing nearly as dramatic as the 800mm.
 
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It gets simpler when you think in terms of what you can do to better isolate a subject or control a background. Then the options are pretty simple - use a lower aperture, get closer to the subject, or use a longer lens. The more advanced steps are to create a specific look in the background, and often that requires a longer lens and changing distance to the subject - as well as aperture selection.

I'm preparing to teach a class on flower photography this weekend. The subjects are largely static, so the concepts are easier to illustrate, but it applies to wildlife as well as flowers or people.

The problem I ran into with the 800mm PF was that at the desired subject distance and size in the frame, the background was more out of focus than I wanted. A shorter lens and getting closer to the subject would make the background clearer - and most likely scare away my subject.
 
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EricBowles said:
It gets simpler when you think in terms of what you can do to better isolate a subject or control a background. Then the options are pretty simple - use a lower aperture, get closer to the subject, or use a longer lens. The more advanced steps are to create a specific look in the background, and often that requires a longer lens and changing distance to the subject - as well as aperture selection.

I'm preparing to teach a class on flower photography this weekend. The subjects are largely static, so the concepts are easier to illustrate, but it applies to wildlife as well as flowers or people.

The problem I ran into with the 800mm PF was that at the desired subject distance and size in the frame, the background was more out of focus than I wanted. A shorter lens and getting closer to the subject would make the background clearer - and most likely scare away my subject.
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Yup ... for me it is easier to demonstrate it than explain it and yes the Z800 is very good at providing out of focus backgrounds whether you want it or not. Z600 f/6.3 a little less so.
 
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For a 600mm lens projecting a FX image, according to the laws of physics that explain optical phenomena.... the total DoF (behind and front of the focal plane) differs by 2cm between f4 and f5.6 at 10m; there is 6cm total increase shutting down from f4 to f8.

Cheat sheet refers
 
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fcotterill said:
For a 600mm lens projecting a FX image, according to the laws of physics that explain optical phenomena.... the total DoF (behind and front of the focal plane) differs by 2cm between f4 and f5.6 at 10m; there is 6cm total increase shutting down from f4 to f8.

Cheat sheet refers
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I've not memorized the math, but I agree that I've learned from experience with long lenses the distance/focal length component is vastly more significant than the aperture for depth of field.
 
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Here's a graphical depiction comparing DoF of 400mm and 560mm lenses at 5m and 10m subject distances, and 800mm at 10m and 20m, with and without ZTC14

1720786552195.png
 
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And the practical side of things - I was photographing songbirds this morning. I was using the Z6iii and 800mm PF. Distances for songbirds ranged from 16-18 feet (near minimum focus distance) to as much as 145 feet (requiring a crop beyond 100%). 145 feet was very tiny in the frame - the subject was a common yellowthroat singing. The comfort level of most birds seemed to be at 75 feet or further from me. On the other hand, for wading birds in flight, 300-400 feet was a typical distance and while they kept their distance, it was a lot easier to have them large enough in the frame.

It's one thing to photograph feeder birds on perches in your yard. Photographing the same birds in the wild without using food is a lot harder and the subject matter is more distant.
 
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EricBowles said:
And the practical side of things - I was photographing songbirds this morning. I was using the Z6iii and 800mm PF. Distances for songbirds ranged from 16-18 feet (near minimum focus distance) to as much as 145 feet (requiring a crop beyond 100%). 145 feet was very tiny in the frame - the subject was a common yellowthroat singing. The comfort level of most birds seemed to be at 75 feet or further from me. On the other hand, for wading birds in flight, 300-400 feet was a typical distance and while they kept their distance, it was a lot easier to have them large enough in the frame.

It's one thing to photograph feeder birds on perches in your yard. Photographing the same birds in the wild without using food is a lot harder and the subject matter is more distant.
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Perhaps I still misunderstand this terminology, but wouldn't a crop beyond 100% mean the photo would be viewed at a size whereby each pixel of the actual image would need to account for more than one pixel of the photo as viewed?
 
SCoombs said:
Perhaps I still misunderstand this terminology, but wouldn't a crop beyond 100% mean the photo would be viewed at a size whereby each pixel of the actual image would need to account for more than one pixel of the photo as viewed?
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I'd say yes, if 100% crop means one pixel on the screen means one pixel of the image. Of course it depends on the screen.
 
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