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04-17-2016, 08:41 PM   #106
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QuoteOriginally posted by stevebrot Quote
One could only wish that the mods close this thread soon.

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04-18-2016, 09:31 AM   #107
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QuoteOriginally posted by reh321 Quote
Later posts indicated that DOF-related responses were exactly what was wanted:
agreed, it turned out that what he actually wanted all along was to use dof slop to try and cover up the inability to set accurate focus... sound familiar? hint: "f/8 and be there"

as for the "plane of focus" confusion and denial that's been expressed by multiple individuals in this thread:

"One of the key links in the chain of successful image rendering is the precision with which the lens focuses on the main subject. Generally speaking, a photographic lens only provides optimum rendering at maximum image quality of a two-dimensional plane. This plane runs exactly in parallel to the film or sensor in the camera.... The focusing region designated as the depth of field is the extent of the range in the object space of an imaging optical system. This region is rendered in acceptably sharp focus on the focal plane.

You can read about the effect that slight defocusing has on image quality in the article "Measuring lenses objectively" which appears in Camera Lens News Nr. 30 starting on page 24. This article shows how important precise focusing is whenever a photographer intends to produce big enlargements or requires optimum quality for any other reason, and not only when using wide apertures... Any small deviations in the focal plane could potentially diminish the technical achievement of the image or even completely alter the impact of the photo, whether deliberately or not." Manual Focusing | ZEISS United States

this is the full zeiss article mentioned above:

"Three-dimensional characteristics:
It is, of course, a truism that image
definition also depends on whether the
lens is focused correctly. It should thus
also be possible to describe this with MTF
curves; and therefore you are now being
introduced to a third type of MTF curve
which is not so commonly known.
Here the MTF values are not plotted as
functions of the spatial frequency or the
picture height, but of a focus parameter.
For this we measure how the MTF
changes in the longitudinal direction on
the image side of the lens and thus
obtain the following curves: http://lenspire.zeiss.com/en/wp-content/uploads/sites/2/2015/09/cln30_en_web_special_mtf_01.pdf

Last edited by osv; 04-18-2016 at 09:51 AM.
04-18-2016, 10:04 AM   #108
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QuoteOriginally posted by osv Quote
agreed, it turned out that what he actually wanted all along was to use dof slop to try and cover up the inability to set accurate focus... sound familiar? hint: "f/8 and be there"
No, No, No.

The OP wanted sufficient DOF against the case that the primary subject moved and the camera could not be moved:

added: Note use of the phrase "nail focus" {bold italics added by me}
QuoteOriginally posted by panonski Quote
I was just trying to find out, is nail focus begin more in the front, exactly front, or closer to the middle of, what we called acceptable sharpness.

If I nail singer, from 3,4 m away, and he move after focusing 30 cm to me, with his body, will he be in focus if I choose for example f8 or even f11?
Or on the opposite side, If he move away 30 cm from me, after focusing.

Last edited by reh321; 04-18-2016 at 10:21 AM. Reason: added note
04-18-2016, 12:03 PM   #109
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QuoteOriginally posted by osv Quote
... as for the "plane of focus" confusion and denial that's been expressed by multiple individuals in this thread:

"One of the key links in the chain of successful image rendering is the precision with which the lens focuses on the main subject. Generally speaking, a photographic lens only provides optimum rendering at maximum image quality of a two-dimensional plane. This plane runs exactly in parallel to the film or sensor in the camera.... "
Did you actually read this article before you extracted it?? Look at the part I rendered in red! The reason you got "denial" over your use of the term "focus plane" is that you routinely seem to use it as a superior replacement for DOF; that is, you try to use the term to cover the region that is in perfect focus ... but as the words that you yourself copied say, the focus plane is an actual plane - it has only two dimensions {and no depth} so no actual object can be in the "focus plane", they are in some part of the DOF {assuming they are in focus}

04-18-2016, 12:10 PM - 1 Like   #110
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Ultimately it comes down to, not absolute accuracy or precision, but the PRACTICAL value of understanding DOF/HFD and how to use it to best advantage among all the other fine photographic tools available today.

If those 'sloppy' range scales with DOF markings had no inherent value I doubt if every lens maker in the game would still be marketing and manufacturing very expensive lenses with range scales. Follow the money!

Nor would every wanna-be photography author still be addressing the topic instead of declaring it as antiquated and useless as dial phones and buggy whips; manual focusing clutches wouldn't be included on high-end lenses; and the quest for the perfect VF screen wouldn't be a popular topic of discussion.

Somewhere out there, there's an optics designer/engineer LHAO over this thread and more than a few of us still have "Check DOF - Set HFD" high on our personal pre-flight checklists.
Attached Images
 

Last edited by pacerr; 04-18-2016 at 12:15 PM.
04-18-2016, 12:50 PM   #111
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QuoteOriginally posted by reh321 Quote
No, No, No.

The OP wanted sufficient DOF against the case that the primary subject moved and the camera could not be moved:
when you can't move the camera you move the focus ring, not the aperture ring

good grief!

---------- Post added 04-18-16 at 01:09 PM ----------

QuoteOriginally posted by reh321 Quote
they are in some part of the DOF {assuming they are in focus}
i got "denial" because people in this thread don't know as much about cameras as they think they do you certainly keep proving that, by constantly contradicting yourself.

of course the theoretically perfect plane of focus has no depth; light rays are essentially radiation, that has no depth... you obviously never bothered to read the link, because you still think that focusing can be done with the aperture ring.

the claim was, that there is no such thing as a "plane of focus", and i proved that wrong with the zeiss link.
04-18-2016, 01:18 PM   #112
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QuoteOriginally posted by osv Quote
. . . when you can't move the camera you move the focus ring,
Unless, of course, you're anticipating not being able to refine focus for some reason when a critical moment occurs and you want to hedge your solution with the best pre-set ISO, shutter speed and aperture compromise that lighting, circumstances and your choice of gear allows.

And I suspect that's what @Panonski was originally referring to also. Just asking for practical, pragmatic information to help overcome one potentially uncontrollable variable in the enjoyable pursuit of photographic images when AF isn't available. Just for the fun of it, ya know!
04-18-2016, 01:23 PM   #113
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QuoteOriginally posted by pacerr Quote
If those 'sloppy' range scales with DOF markings had no inherent value I doubt if every lens maker in the game would still be marketing and manufacturing very expensive lenses with range scales. Follow the money!
fa31 is your idea of a modern lens? you need to get out more

the last lens that i bought is the tamron 150-600, it doesn't have any dof scale; that's where the future is, and it's here now with modern lenses.

as i understand it, canon has responded to the situation by putting a feature in the camera body that automatically sets the dof for you; just point the lens at each limit of where you want the dof to start and end, hit the af button, and wala! the camera body has picked the aperture.

04-18-2016, 02:37 PM   #114
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QuoteOriginally posted by osv Quote
the last lens that i bought is the tamron 150-600, it doesn't have any dof scale; that's where the future is, and it's here now with modern lenses.
No wonder, that there is no dof scale, it's because it is a zoom. Only with sliding zooms is a chance for a DOF-scale.
04-18-2016, 02:43 PM   #115
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QuoteOriginally posted by osv Quote
when you can't move the camera you move the focus ring, not the aperture ring
You obviously live in a world different from ours, and just don't understand our world. In your world, cars come down a track very fast, but nature penalizes them if they vary from their chosen path. The rest of us have much less certainty in our lives.

For example, some years ago my daughter played basketball; all the adults loved to watch her because she put so much of herself into the game. Over time her knees starting bothering her, and the trainer, who was one of those adults who enjoyed watching her play, knew what the problem was without actually examining her knees. He gave her what she called "dorky volleyball kneepads", because he knew that whenever the officials sorted through a pile of players looking for the ball, they would find her at the bottom of it, and that constantly hitting the floor following the ball was her problem. When I took pictures of her, I zoomed back a bit because I wanted to show her in the context of her opposition, but if I had tried to photograph her tight up, I would have used a smallish aperture because I knew that when I took a picture of her, she would be nowhere close to where she had been when I focused the camera {and chimped to check on focus??}. That is exactly the problem the OP was asking about, and what most of us have been talking about all along. You have been in your own Sony world where "chimping" solves problems. Please write this down so you can remember it for a few seconds: aperture ring does not change focus; it changes the amount of area seen by observers as being in focus, and thus protects from last second unexpected movement.

QuoteOriginally posted by osv Quote
i got "denial" because people in this thread don't know as much about cameras as they think they do; you certainly keep proving that, by constantly contradicting yourself.
Of course the theoretically perfect plane of focus has no depth; light rays are essentially radiation, that has no depth...
No! No! No!
You got denial because you insisted on using words indicating that "focus plane" has depth, that the area of perfect focus is more than a molecule thick. Even the words you quoted contradict you.
I have not contradicted myself - you have constantly misrepresented what I said.

The plane of focus having no depth has nothing to do with radiation or light waves; science takes its vocabulary, words and their meanings, from math, and the definition of plane says that a point has zero dimensions, a line has one dimension, a plane has two dimensions, and a solid has three dimensions. That is why any plane, including a focus plane, has two dimensions.

I have taught at the college level off-and-on over the years. In teaching introductory courses, I have become more and more focused on vocabulary - can my students use a word correctly and do they understand correctly when someone else says something. You're not doing very well in either category.

QuoteOriginally posted by osv Quote
you obviously never bothered to read the link, because you still think that focusing can be done with the aperture ring.
No, No, No
I have never said that.
Aperture narrows or widens the area of "acceptable focus"; some people use that to "isolate" the subject, while the OP wanted to go in the other direction to widen possibilities/options.

QuoteOriginally posted by osv Quote
the claim was, that there is no such thing as a "plane of focus", and i proved that wrong with the zeiss link.
No! No! No!
The claim was that you were misusing the term, and your own article proved that you were.
Over and over you used words indicating confusion between "plane of focus" and DOF.

Last edited by reh321; 04-18-2016 at 03:41 PM.
04-18-2016, 03:06 PM   #116
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QuoteOriginally posted by osv Quote
. . . fa31 is your idea of a modern lens?
Modern? Nope. Still available new though. Just a good, useful, rather "expensive" example of an AF lens that didn't REALLY need a scale for AF bodies at the time but pros seem to appreciate the convenience. I suppose I could've found a similar Leica or Canikon example, but . . .

QuoteOriginally posted by osv Quote
. . . a feature in the camera body that automatically sets the dof for you; just point the lens at each limit of where you want the dof to start and end, hit the af button, and wala! the camera body has picked the aperture
WOW, neat-o! I gotta try that. Let's see now. It's twilight - exposure sez I'll need f 1.8 @ 1/30th - an' I just wave (um, point?) the lens at the horizon and then at MFD and push a button and . . ." wala!" (Wala? Is that some new kind'a bokeh or what?)

Wait, I'm confused - it "sets the dof" or . . . "picked the aperture" . . . or maybe re-wrote the physical laws of optics an' light and published 'em in 43 languages?
04-18-2016, 03:41 PM   #117
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QuoteOriginally posted by joergens.mi Quote
No wonder, that there is no dof scale, it's because it is a zoom. Only with sliding zooms is a chance for a DOF-scale.
a lot of modern primes don't have dof scales either... the new tamron 35/1.8 for example; if you get a distance scale on a modern lens, it'll usually have short rotation, so there isn't much precision... no infra-red marks, and often no fixed infinity hard stop either.

with a lens like that, people will have to learn how to set accurate focus with the focus ring.
04-18-2016, 03:45 PM   #118
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QuoteOriginally posted by osv Quote
a lot of modern primes don't have dof scales either... the new tamron 35/1.8 for example; if you get a distance scale on a modern lens, it'll usually have short rotation, so there isn't much precision... no infra-red marks, and often no fixed infinity hard stop either.

with a lens like that, people will have to learn how to set accurate focus with the focus ring.
People already set accurate focus with the focus ring.
They will have to learn to estimate DOF without help from the lens and without "chimping".
04-18-2016, 03:58 PM   #119
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QuoteOriginally posted by pacerr Quote
I suppose I could've found a similar Leica or Canikon example, but . . .
maybe like the canon 35/2 usm? yeah, it's got dof markings... f/11 and f/22 Canon EF 35mm f/2 IS USM Review | PhotographyBLOG

is that canon telling people that dof calculations are only accurate at diffraction-impacted apertures? hilarious!

QuoteOriginally posted by pacerr Quote
WOW, neat-o! I gotta try that. Let's see now. It's twilight - exposure sez I'll need f 1.8 @ 1/30th - an' I just wave (um, point?) the lens at the horizon and then at MFD and push a button and . . ." wala!" (Wala? Is that some new kind'a bokeh or what?)

Wait, I'm confused - it "sets the dof" or . . . "picked the aperture" . . . or maybe re-wrote the physical laws of optics an' light and published 'em in 43 languages?
well, how would you set dof without picking an aperture? i'd like to see that trick i have no idea how the exposure gets handled at twilight, maybe it throws iso10000 at the shot?? if a shooter was using that auto-dof trick, would he really be competent enough know any better??

---------- Post added 04-18-16 at 04:06 PM ----------

QuoteOriginally posted by reh321 Quote
People already set accurate focus with the focus ring.
only people who know how to use cameras, and people who have the right gear, set accurate focus with the focus ring.

i'm still waiting for you to tell us how to use hyperfocal calcs on a lens that doesn't have any dof markings, and a short distance rotation...
04-18-2016, 04:27 PM   #120
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QuoteOriginally posted by osv Quote
only people who know how to use cameras, and people who have the right gear, set accurate focus with the focus ring.

i'm still waiting for you to tell us how to use hyperfocal calcs on a lens that doesn't have any dof markings, and a short distance rotation...
It is harder. You can use one of the calculators that were mentioned in the early days of this thread, when more people were interested or
you can have a general understanding of them, perhaps from having used the older lenses or calculators. I'm still not convinced that "chimping" is
much of a solution other than perhaps for being a slower and less-exact version of the calculators to be used if you don't have an older lens.

In any case, that is why the OP asked the question in the first place.
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