depth of field

[Jenningsmca]

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I have watched a few photo shoots lately, on youtube, where the photographer was using the lens wide open with natural light.

 

I have looked up the dof of my Summilux lens at f/1.4 with a subject distance of 6 ft there is less than a foot of focus distance.

 

When do you normally shoot a summilux lens wide open and get everything in focus ?

 

 

Subject distance  6 ft   Depth of field  Near limit  5.65 ft Far limit  6.4 ft Total  0.75 ft   In front of subject  0.35 ft (47%) Behind subject  0.4 ft (53%)   Hyperfocal distance  94.8 ft Circle of confusion  0.03 mm

 

 

[LD_50]

You won’t have “everything” in focus wide open at 6 ft unless “everything” is planar at that distance.

 

I assume the YouTube videos don’t show high quality examples of the resulting photos so you likely won’t see the effects of the shallow DOF.

 

Go shoot some targets wide open at different distances and see what you like. It’s up to you if it matches what you’re after. If not, simply change aperture and/or working distance.

[Michael Geschlecht]

Hello Jenningsmca,

 

Welcome to the Forum,

 

You have asked a complex question. Meaning: A question which is actually a number of questions.

 

The answer to the first part: "When do you................and get everything in focus?"

 

Is: Sometimes.

 

Because having the entire scene in focus (Within acceptable depth of field.) is partially dependent on: How large (wide) the lens opening is. And it is also partially dependent on: How far from that scene: The camera & lens are.

 

As well as being partially dependent on: How far the camera & lens are from the nearest part of the scene that that the photographer wants to be in focus. 

 

As well as: How far away the camera & lens are from the furthest part of the scene that the photographer wants to be in focus.

 

If you look on the lens barrel you will see a series of numbers which represent the range of distances that, that individual lens focuses over.

 

You will also see a series of numbers such as:  2 - 2.8 - 4 - 5.6  and so on moving out from a central line, or mark, that represents the actual distance that the lens is then focused at. These numbers show how much of the scene in front of & behind this point of focus will be in acceptable focus: When that specific lens is focused at that given aperture.

 

These numbers represent acceptable "depth of field" at a certain standard which is: The theoretical distance from that current point of focus at which: That specific lens will produce acceptable images: At the given lens opening: That the numbers on the lens barrel represent. Both in front of & behind the point focused at.

 

This is a lot of information for a start.

 

There is more. Please ask.

 

Best Regards,

 

Michael

Edited February 27, 2018 by Michael Geschlecht

[jaapv]

I smell a number of common misconceptions here:

 

1. DOF is not reality; it is an optical illusion created by the lack of resolution of the human eye.

2. DOF is not a block of sharpness floating in a sea of Bokeh; it is the gradient of acceptable UNsharpness in front of and behind the plane of focus (sharpness).

3. DOF is determined by the magnification throughout the system, i.e. subject distance, sensor size/crop, enlargement of the print and viewing distance.

4. DOF is influenced by subject matter; a forest in high contrast will have more shallow DOF than a foggy landscape. A uniformly gray image will have infinite DOF.

5. DOF is influenced by the contrast and resolution of the lens, plus some other lens design parameters.

6. DOF is influenced by the acuity of vision  and tolerance of unsharpness of the viewer.

 

In other words, there is no answer to your question. The only judge of acceptable DOF are you yourself.

[lx1713]

 

 

I have looked up the dof of my Summilux lens at f/1.4 with a subject distance of 6 ft there is less than a foot of focus distance.

 

When do you normally shoot a summilux lens wide open and get everything in focus ?

 

 

Subject distance  6 ft   Depth of field  Near limit  5.65 ft Far limit  6.4 ft Total  0.75 ft   In front of subject  0.35 ft (47%) Behind subject  0.4 ft (53%)   Hyperfocal distance  94.8 ft Circle of confusion  0.03 mm

 

 

I think specifically to the words in bold: when everything in your image sits in the same plane of focus. Like a brick wall shot parallel to your sensor.

Edited February 27, 2018 by lx1713

[dancook]

Wide open and everything in focus..  works when the scene is at a distance from the camera, the wider focal length the lens is the easier it is.

 

Venice by dancook1982, on Flickr

Edited February 27, 2018 by dancook

[Irakly Shanidze]

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Just a practical observation: when shooting Noctilux at f/1, and you have a six-foot-tall person occupying some 90% of hight of a horizontal frame, DOF is just enough to get the person completely in focus on a 8x12" print.

[Jared]

 

I have watched a few photo shoots lately, on youtube, where the photographer was using the lens wide open with natural light.

 

I have looked up the dof of my Summilux lens at f/1.4 with a subject distance of 6 ft there is less than a foot of focus distance.

 

When do you normally shoot a summilux lens wide open and get everything in focus ?

 

 

Subject distance  6 ft   Depth of field  Near limit  5.65 ft Far limit  6.4 ft Total  0.75 ft   In front of subject  0.35 ft (47%) Behind subject  0.4 ft (53%)   Hyperfocal distance  94.8 ft Circle of confusion  0.03 mm

 

 

 

Those numbers are correct for a 35mm lens at 2m; I assume your Summilux is a 35?  

 

The question, though, is what circle of confusion should one be using for "acceptably sharp" depth of field?  The 0.03mm standard was based on an A4 print and a viewing distance of 25cm (8x10 from 10in distance).  Many people would like to be able to make larger prints than that while maintaining viewing distance.  Plus, the 0.03mm circle of confusion size assumed 35mm format (full frame).  Many people now use APS-C, 4/3", and even medium format, so the calculations would be different for those chip sizes.  

 

Zeiss used to use a standard of (format diagonal)/1700.  With a full frame camera that would yield 0.025mm rather than 0.03mm.  That formula is independent of format which is nice, but it still assumed an A4 print size.  Unfortunately, there is no hard and fast rule that most photographers would accept since it really depends on the photographer's standards and on the combination of print size and viewing distance.  I think most photographers these days would not consider 0.025mm conservative enough for modern cameras--our expectations on image quality have gone up over the years.  

 

Let's assume you are using a 24 megapixel camera and you will accept a blur size of three pixels for subjects within your defined DoF.  That would give you a CoC diameter of 0.018mm.  With your 35mm lens that would give you:

 

Subject distance of 6 ft

Aperture of f/1.4

Near focus of 5ft 9.4in

Far focus of 6ft 2.8in

Total DoF of 5.3in

Hyperfocal distance of 159ft 6in

 

Not a lot of margin to play with if you want a larger print.  Probably enough for an environmental portrait, though.  You'd get both eyes, nose, and ears within your DoF.  Frankly, most people doing portraits would want a somewhat longer focal length, though, and an even narrower DoF in order to isolate the subject a bit better, even at the cost of some sharpness on the nose and ears.  

[FlashGordonPhotography]

The only two constants regarding depth of field are that any thread started about it will go for at least 8 pages and that half the information in those 8 pages will be wrong. Everything else is subject to interpretation.

 

 

Gordon

[Jenningsmca]

Just a practical observation: when shooting Noctilux at f/1, and you have a six-foot-tall person occupying some 90% of hight of a horizontal frame, DOF is just enough to get the person completely in focus on a 8x12" print.

 

Never quite thought of it that way.

[Jenningsmca]

Hello Jenningsmca,

 

Welcome to the Forum,

 

You have asked a complex question. Meaning: A question which is actually a number of questions.

 

The answer to the first part: "When do you................and get everything in focus?"

 

Is: Sometimes.

 

Because having the entire scene in focus (Within acceptable depth of field.) is partially dependent on: How large (wide) the lens opening is. And it is also partially dependent on: How far from that scene: The camera & lens are.

 

As well as being partially dependent on: How far the camera & lens are from the nearest part of the scene that that the photographer wants to be in focus. 

 

As well as: How far away the camera & lens are from the furthest part of the scene that the photographer wants to be in focus.

 

If you look on the lens barrel you will see a series of numbers which represent the range of distances that, that individual lens focuses over.

 

You will also see a series of numbers such as:  2 - 2.8 - 4 - 5.6  and so on moving out from a central line, or mark, that represents the actual distance that the lens is then focused at. These numbers show how much of the scene in front of & behind this point of focus will be in acceptable focus: When that specific lens is focused at that given aperture.

 

These numbers represent acceptable "depth of field" at a certain standard which is: The theoretical distance from that current point of focus at which: That specific lens will produce acceptable images: At the given lens opening: That the numbers on the lens barrel represent. Both in front of & behind the point focused at.

 

This is a lot of information for a start.

 

There is more. Please ask.

 

Best Regards,

 

Michael

 

I have used this when trying out zone focusing for Street Photography.

[otto.f]

I smell a number of common misconceptions here:

 

1. DOF is not reality; it is an optical illusion created by the lack of resolution of the human eye.

 

Very strange statement. DOF is a concept typically defined for a range of sharpness in a two-dimensional image created with a camera with a lens. We’re not talking about how the naked eye sees reality here, that’s something which is irrelevant here. We are talking about the reality of the created image.

[Irakly Shanidze]

Very strange statement. DOF is a concept typically defined for a range of sharpness in a two-dimensional image created with a camera with a lens. We’re not talking about how the naked eye sees reality here, that’s something which is irrelevant here. We are talking about the reality of the created image.

 

As strange as it sounds, the statement is correct. . Only at one distance from the sensor the focus can be critically sharp, which happens to be at the plane of focus. DOF is what our eyes see as sharp in front of and behind the object in focus ON THE PICTURE, not in real life.

[otto.f]

As strange as it sounds, the statement is correct. . Only at one distance from the sensor the focus can be critically sharp, which happens to be at the plane of focus. DOF is what our eyes see as sharp in front of and behind the object in focus ON THE PICTURE, not in real life.

Which is in my opinion sheer humbug, would-be acting scientific/philosophic by playing with concepts. A picture is part of real life. Magritte illustrated this from the other side with his painting ‘ce n’est pas un pipe’. The picture and the reality depicted on the picture are two totally different parts of reality which you cannot share under DOF. DOF is a characteristic of a photograph. To call this an optical illusion is nonsense, it’s just mixing different parts of reality.

[jaapv]

Sorry, Lot. Unfortunately not a matter of opinion. If your eye had more resolution, you would see less DOF. The only reason the concept exists is because your eye cannot resolve beyond a certain limit.

[thighslapper]

Which is in my opinion sheer humbug, would-be acting scientific/philosophic by playing with concepts. A picture is part of real life. Magritte illustrated this from the other side with his painting ‘ce n’est pas un pipe’. The picture and the reality depicted on the picture are two totally different parts of reality which you cannot share under DOF. DOF is a characteristic of a photograph. To call this an optical illusion is nonsense, it’s just mixing different parts of reality.

 ....... errr...... what about using binoculars or a telescope ....... or for that matter viewing on the EVF/screen ??  ..... there is again a situation where there is only one point at which the subject is technically in focus from the viewpoint  of physics ....... but the resolution limitations of the eye give an zone before and beyond the point of focus that appears to be in focus as far as the discrimination of the humans optical system is concerned. 

 

Surely what is 'in focus' depends on the resolving power of the system that is viewing or recording the image produced by the optical system .... and where you set the limits of the zone of 'acceptable focus' for lenses and cameras is historical and based purely on a pragmatic set of criteria .....

 

(sorry .... Jaap beat me to it in a rather more succinct way)

Edited March 1, 2018 by thighslapper

[otto.f]

Sorry, Lot. Unfortunately not a matter of opinion. If your eye had more resolution, you would see less DOF. The only reason the concept exists is because your eye cannot resolve beyond a certain limit.

You’re not talking about a 2d picture here, but about seeing the 3d world with your eyes. You’re still comparing two different kinds of reality.

[pico]

The eye/brain is not a camera. A picture is not reality; not even close.

 

At distances of about nine feet or less the eye cannot see but a narrow area. The eye is always moving (scanning or vibrating if you prefer) and if it were not for persistence of vision (the brain) we would hardly resolve anything. The brain 'sees' the moment, the eye moves, persistence of vision maintains the previous 'look' long enough to merge the current image, and this continues. Persistence has a limit, too - if the eye does not move/scan for a few seconds the persistent image is not held - the focused part of the image will vanish.

Edited March 1, 2018 by pico

[FlashGordonPhotography]

Very strange statement. DOF is a concept typically defined for a range of sharpness in a two-dimensional image created with a camera with a lens. We’re not talking about how the naked eye sees reality here, that’s something which is irrelevant here. We are talking about the reality of the created image.

 

Actually DoF is described as a range of acceptable sharpness......

 

And the answer to the original question. "When do you normally shoot a summilux lens wide open and get everything in focus ?" 

 

Almost never. That's not the point of "wide open".

 

Gordon

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Hallo,

Look here: Leica L-Mount

[jaapv]

You’re not talking about a 2d picture here, but about seeing the 3d world with your eyes. You’re still comparing two different kinds of reality.

No, I am talking about the eye resolving details on a print.