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Stacking for panorama - Understanding Depth of Field variables
Dec 13, 2017 15:57:57   #
Rongnongno Loc: FL
 
Before using stacking of images to achieve a greater depth of field (DoF) for panoramas it is useful to understand what will affect how you implement stacking and how they are interrelated.

This is not about teaching or explaining DoF but how to use it when stacking.

Aperture, along with the shutter speed, is understood to be a way to control light. More importantly Aperture also controls the DoF.

Variables that affect DoF:
1) Lens: Minimum and maximum aperture are set by the design of the lens.
2) Distance: The closer the subject is to the camera/lens the shallower the DoF. The further away the deeper. This is independent of lens focal length and aperture setting.
3) Aperture: Aperture controls the flow of light in the camera and also controls DOF. The larger the 'brighter'. The DoF is shallow. The smaller the 'darker'. The DoF is deep.

Caveats:
1) Lens: Long lenses visually compress the perspective. These are not really suitable for stacking due to the limited DoF. Mid-range telephotos and normal lenses are ideal for stacking. Wide angle lenses can be stacked successfully.
2) Distance: The focus plane distance from the camera determines the DoF. The closer, the shallower.
3) Aperture: Lenses have an optimal aperture. Using something else than that will create a soft capture.

Summary: The three factors - lens focal length, distance between the subject's focal plane and the camera, and the aperture all control the DoF.

DoF distribution: While widely accepted the DoF distribution of 1/3 in front 2/3 in back of the focus plane is mostly correct it is not all that simple. For convenience sake we will use the DoF generic accepted distribution.

This is written in collaboration with Bob, Gene and RGG.

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Dec 20, 2017 08:46:27   #
MichaelH Loc: NorCal via Lansing, MI
 
Hello Ron, I got here from the Part 2 sensing that (if I did not know what aperture was) I might need to know how to determine what my lens' optimal (aka "sharpest") aperture is. Does one determine a particular lens' optimal aperture by doing test images at different distances and varying the aperture and reviewing the results? Or does one look it up somewhere? This might be handy information to include in this tutorial.

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Dec 20, 2017 13:31:19   #
Rongnongno Loc: FL
 
MichaelH wrote:
Hello Ron, I got here from the Part 2 sensing that (if I did not know what aperture was) I might need to know how to determine what my lens' optimal (aka "sharpest") aperture is. Does one determine a particular lens' optimal aperture by doing test images at different distances and varying the aperture and reviewing the results? Or does one look it up somewhere? This might be handy information to include in this tutorial.

We have lens as a topic coming soon, when Gene comes back from his vacation in Europe. Gene will be the main writer this time. He has a deep knowledge on lenses that I do not have. (Sorry, Gene, just volunteered you)

Usually lens optimal distance is determined by the specialization but trying to find this out yourself can be interesting. A portrait lens by example 80mm to 150mm offer a working (optimal) distance that does not crowd the model(s) and offer the sharper capture possible (then comes the aperture). A macro lens on the other end needs to be really close to the subject.

I am sure that googling it can satisfy your curiosity. This has to do with diffraction. Even a 'tack focused capture' can be soft due to diffraction. We see this all over the gallery. There are ways to correct this w/o using a destructive sharpening technique.

-----
* Some are simple others are... Entertaining and yet others are really complex but still incomplete in their simulation. There is one that includes the three!!! You can download it so that it is always available even if there is no connection... Incomplete? The 'model' is a vector image so there is no diffraction indication...

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Dec 20, 2017 20:43:04   #
MichaelH Loc: NorCal via Lansing, MI
 
Neat simulator. Thank you.

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Dec 26, 2017 10:19:24   #
Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)
 
Rongnongno wrote:
We have lens as a topic coming soon, when Gene comes back from his vacation in Europe. Gene will be the main writer this time. He has a deep knowledge on lenses that I do not have. (Sorry, Gene, just volunteered you)

Usually lens optimal distance is determined by the specialization but trying to find this out yourself can be interesting. A portrait lens by example 80mm to 150mm offer a working (optimal) distance that does not crowd the model(s) and offer the sharper capture possible (then comes the aperture). A macro lens on the other end needs to be really close to the subject.

I am sure that googling it can satisfy your curiosity. This has to do with diffraction. Even a 'tack focused capture' can be soft due to diffraction. We see this all over the gallery. There are ways to correct this w/o using a destructive sharpening technique.

-----
* Some are simple others are... Entertaining and yet others are really complex but still incomplete in their simulation. There is one that includes the three!!! You can download it so that it is always available even if there is no connection... Incomplete? The 'model' is a vector image so there is no diffraction indication...
We have lens as a topic coming soon, when Gene com... (show quote)


It's ok RGG - that's what this forum is about . . . Hope you had a fine Christmas!

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