Usability of Zone Focusing

Started Oct 22, 2020 | Questions
Mark S Abeln
Mark S Abeln Forum Pro • Posts: 18,900
Re: Usability of Zone Focusing
2

Gurusathiy wrote:

Hope all are doing good and life's back to almost normal while still in midst of pandemic...

So after spending an year more on research on this topic, I've still not found an exact answer to my conundrum;-) so I've few more questions to all those experts here to help me further in my quest for focus-less pic taking...

What I recommend last year is what I still recommend today: "I think it is important that someone doesn’t let their theoretical understanding outpace their practical experience by too much."

If you are still having great difficulties understanding depth of field, I would suggest that you directly focus on the most important object in your scene, and not worry about depth of field. Only worry about it if you don't have sufficient sharpness on some objects within your photograph. Please ask yourself these questions:

  • Are your results good enough?
  • Or are you seeing problems with focus and sharpness in your photos?

I also recall that you were having difficulties when photographing with friends, because they would instantly snap a photo with their smartphones while you were still struggling with focus and depth of field. Depth of field really shouldn't be that difficult.

Pardon me for the long post:

My friend has got a Zeiss 25mm Biogon ZM lens and I'm trying it on my A6000 with K&F concept pro adapter.

OK, so that adapter has no optics and so won't change the optical formula of the lens. You will get a narrower angle of view on your camera than you would if that lens is mounted on a full frame camera, which will affect the depth of field.

I came across this thread on hyperfocal focusing for FF lens on APS-C:

https://www.dpreview.com/forums/thread/3970117

As per Jim's advise, if I use f/8 aperture and keep the focusing ring to two f/4 markings (2 stops wider than taking aperture), will the image have depth of field of f/4 or taking aperture f/8?

Those old lenses are designed to be used on a full frame camera, and the depth of field markings are valid only for that format, and they make certain assumptions about the viewing conditions for the final image.

If you set the lens to f/8, your exposure setting will still be f/8, but your depth of field will be smaller. If you want to get the same depth of field on that lens that you would get on a full frame camera, then you have to multiply the f/stop by the crop factor of your camera, which is 1.5, or f/12.

This will give a pretty deep depth of field. But do you really need everything from about seven feet away to infinity to look sharp? Is there anything at all in your photograph that is actually that close? Is the air clean and clear enough that distant objects actually won't be obscured by haze?

Or is there only one object in the scene which really catches your eye, which is really important for your composition? If so, just focus on that, and don't worry too much about depth of field.

As an experiment, try using that lens wide open at f/2.8, and just focus on the most important object in the scene, and see if your resulting photos are adequate.

Also, every research gave me this as the method to set the lens focus ring for indicating range of distance that will be in focus:

This is from dofmaster site.

But, as per Zeiss website, the below setting contradicts that and says infinity mark be aligned to the center focus index and aperture setting be read accordingly:

As per Zeiss

If HFD is as simple as aligning the markings as per these methods, I'm hard pressed to understand the discussions around CoC and having low CoC value for digital sensors and adjusting focus ring as per HFD charts with CoC in the math.

So what is the right method? DOF or Zeiss?

The hyperfocal focus distance itself depends on the circle of confusion. The lens markings are dependent on the circle of confusion, which may not always be adequate for you.

There are two methods of hyperfocal focus distance: one is that you focus on the hyperfocal distance, and then everything from half the hyperfocal distance to infinity will be adequately sharp, and the other method is to focus to infinity, and then everything from the hyperfocal focus distance to infinity will be adequately sharp.

In the first method, only objects at the HFD will be sharp, and objects before and after will be slightly out of focus. In the second method, only infinity will be sharp, and closer objects will be slightly out of focus.

It goes back to my earlier advice: focus on the most important thing in your scene, and then only worry about depth of field if your results aren't good enough.

Any support on this is highly appreciated!!

 Mark S Abeln's gear list:Mark S Abeln's gear list
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alcelc
alcelc Forum Pro • Posts: 17,556
Re: Usability of Zone Focusing

One more thing you might have overlooked when comparing to the DoF scale marking on the 2 lenses:

1 lens is 50mm and the other is 35mm?

DoF is determined by:

  • The focal length,
  • The aperture, and
  • The shooting distance.

Mind you, crop factor will also play a role on comparing cross sensor size system.

Since the focal length is different, the DoF is different

Might try to play on the following to know the approximate DoF condition on the combination of above 3 factors:

https://www.dofmaster.com/dofjs.html

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Albert
** Please forgive my typo error.
** Please feel free to download my image and edit it as you like **

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OP Gurusathiy Junior Member • Posts: 25
Re: Usability of Zone Focusing

Hi Mark,

Thanks for the patience & time to help again. I'll use the below tip for sure.

Mark Scott Abeln wrote:

Please ask yourself these questions:

  • Are your results good enough?
  • Or are you seeing problems with focus and sharpness in your photos?

There are two methods of hyperfocal focus distance: one is that you focus on the hyperfocal distance, and then everything from half the hyperfocal distance to infinity will be adequately sharp, and the other method is to focus to infinity, and then everything from the hyperfocal focus distance to infinity will be adequately sharp.

In the first method, only objects at the HFD will be sharp, and objects before and after will be slightly out of focus. In the second method, only infinity will be sharp, and closer objects will be slightly out of focus.

It goes back to my earlier advice: focus on the most important thing in your scene, and then only worry about depth of field if your results aren't good enough.

Any support on this is highly appreciated!!

This is much helpful to understand on HFD!! will use it as per my requirements.

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Thanks
Guru raj

OP Gurusathiy Junior Member • Posts: 25
Re: Usability of Zone Focusing

hi Albert,

Thanks for pointing it out, yes both are different lenses but I was more interested in understanding how to position the distance scale of any lens for HFD focusing!!

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Thanks
Guru raj

alcelc
alcelc Forum Pro • Posts: 17,556
Re: Usability of Zone Focusing

I hate MF, not sure whether I could help.

But from your correspondence here it seems you can actually look at it ina more simple way.

1. since you are using a 1.5x crop factor system, any reading you read, if based on FF (1.0X crop factor), must be multiplied by 1.5 on Angle of View (i.e. a 50mm FF lens on APSC offers an equivalent view of 75mm @ the same shooting distance) as well as DoF (i.e. the DoF scale of f/8 of the lens has to use the marking of f/12 of that lens).

It is never a problem for FF system shooter, but not easy for other crop factor system user. I suppose we could calculate the DoF by DoF calculator in advance and put them on a chat sheet might be more useful than using the DoF scale directly on lens.

2. If focusing by zone focus (hyperfocal distances), just set the f/stop and keep the target within the expected DoF range (avoid to use the both ends of DoF range), by theory you can capture an image with reasonable sharpness ( never as sharp as you lock focus on it) of that intended target.

In practice, when you find a target:

  • set the f/stop and move close to the target until it falls within the DoF of your set f/stop, or
  • estimate the distance of the target from you, set the f/stop that can provide an DoF to cover that distance.

I learnt those back from the full manual SLR day when my poor eyesight did not happy to work with those split focusing glass.

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Albert
** Please forgive my typo error.
** Please feel free to download my image and edit it as you like **

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Jessica M Regular Member • Posts: 244
Solving the wrong problem

I’ve never encountered a photography enthusiast who didn’t want to be bothered with focusing the camera.

OP Gurusathiy Junior Member • Posts: 25
Re: Solving the wrong problem

May be I'm not an expert on how to focus quickly, as I said earlier, autofocus is not something that suits me nor I'm enjoying the need to magnify each time in MF to see if things are sharp in landscapes.. That's the reason for the post, to get some advise from experts on zone/hyperfocal...

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Thanks
Guru raj

Klaus dk
Klaus dk Veteran Member • Posts: 8,942
Re: Usability of Zone Focusing

Gurusathiy wrote:

Hello All,

Hope all are doing good and life's back to almost normal while still in midst of pandemic...

So after spending an year more on research on this topic, I've still not found an exact answer to my conundrum;-) so I've few more questions to all those experts here to help me further in my quest for focus-less pic taking...

Pardon me for the long post:

My friend has got a Zeiss 25mm Biogon ZM lens and I'm trying it on my A6000 with K&F concept pro adapter.

I came across this thread on hyperfocal focusing for FF lens on APS-C:

https://www.dpreview.com/forums/thread/3970117

As per Jim's advise, if I use f/8 aperture and keep the focusing ring to two f/4 markings (2 stops wider than taking aperture), will the image have depth of field of f/4 or taking aperture f/8?

Also, every research gave me this as the method to set the lens focus ring for indicating range of distance that will be in focus:

This is from dofmaster site.

But, as per Zeiss website, the below setting contradicts that and says infinity mark be aligned to the center focus index and aperture setting be read accordingly:

As per Zeiss

If HFD is as simple as aligning the markings as per these methods, I'm hard pressed to understand the discussions around CoC and having low CoC value for digital sensors and adjusting focus ring as per HFD charts with CoC in the math.

So what is the right method? DOF or Zeiss?

Any support on this is highly appreciated!!

It's scary and probably even stupid to disagree with Zeiss on anything optics, but I'd say the first direction is correct: Set the infinity mark at the rightmost f-stop mark to set the lens to hyperfocal distance for that f-stop.

As everybody else have pointed out, these are FF lenses, and your camera is APS-C, so you have a deeper DoF.

There are some caveats, though. First, the CoC depends on the medium and the expected usage. A high resolution APS-C sensor would have a smaller CoC than a fast negative film, for instance, and a wall sized print viewed close up demands a very small CoC, if you want it "pin sharp".

And I'll also repeate what others have written: There Is No Set And Forget Focus Setting. If you want phone functionality, use a phone.

I support the suggestion for a solid tripod. I've found reading Thom Hogan's considerations worth while.

Good luck and good light.

 Klaus dk's gear list:Klaus dk's gear list
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OP Gurusathiy Junior Member • Posts: 25
Re: Usability of Zone Focusing

Klaus dk wrote:

It's scary and probably even stupid to disagree with Zeiss on anything optics, but I'd say the first direction is correct: Set the infinity mark at the rightmost f-stop mark to set the lens to hyperfocal distance for that f-stop.

As everybody else have pointed out, these are FF lenses, and your camera is APS-C, so you have a deeper DoF.

There are some caveats, though. First, the CoC depends on the medium and the expected usage. A high resolution APS-C sensor would have a smaller CoC than a fast negative film, for instance, and a wall sized print viewed close up demands a very small CoC, if you want it "pin sharp".

And I'll also repeate what others have written: There Is No Set And Forget Focus Setting. If you want phone functionality, use a phone.

I support the suggestion for a solid tripod. I've found reading Thom Hogan's considerations worth while.

Good luck and good light.

hi Klaus,

Thanks for the inputs, I've to convince myself that there is no shortcut to my conundrum.. One thing I want to understand is on CoC.. if as per hyperfocal I set infinity to f/8.0 mark for taking aperture (we'll keep aside crop factor for now), where does this CoC will come into play? Is that subject distance changes or focus distance changes (in case if its just a scenery) as per math on CoC to ensure sharp images?

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Thanks
Guru raj

Jessica M Regular Member • Posts: 244
Re: Solving the wrong problem
1

Gurusathiy wrote:

May be I'm not an expert on how to focus quickly, as I said earlier, autofocus is not something that suits me nor I'm enjoying the need to magnify each time in MF to see if things are sharp in landscapes.. That's the reason for the post, to get some advise from experts on zone/hyperfocal...

Okay - now I understand, thank you for explaining.

Perhaps this might help your understanding and answer your question.

There are several levels of  ‘focus’ or ‘sharpness - at least this is how I think of it.

  1. The first is ‘critical sharp’.  I need critical sharp when the image will be printed very large (greater than 20”) and people are likely to view this image at a close distance and study its details. This is typically how I shoot landscapes.  I go through the effort of using a solid tripod, locking up the mirror, and (as you mentioned) magnifying in MF.  
  2. Next would be what I consider ‘sharp’.  I just use AF and make sure I have the correct AF settings that make sense given the scene.  That is matrix for a soccer game or the zoo.  Single point for portrait.  AF on modern cameras are darn fast and accurate.
  3. Lastly, there’s what I call ‘sharp enough’.  In this category, there are two techniques: zone focus and hyperfocal.  Both rely on depth-of-field but have different uses. I would say, IMHO, that the zone focus technique is only really useful for cameras which don’t have AF and where there’s no time to focus.  It’s good for situations where capturing the ‘moment’ is by far the priority, such as in street photography. Hyperfocal is a specific technique used to get the subject plus the entire scene (foreground to background) reasonably sharp.  Hyperfocal technique requires some calculations and distance estimates.  

One of the reasons I’m struggling with your question is that you want ‘critical sharp’ using techniques for ‘sharp enough’.  The thing you’re asking is not possible.

Mark S Abeln
Mark S Abeln Forum Pro • Posts: 18,900
Re: Usability of Zone Focusing
1

Klaus dk wrote:

It's scary and probably even stupid to disagree with Zeiss on anything optics, but I'd say the first direction is correct: Set the infinity mark at the rightmost f-stop mark to set the lens to hyperfocal distance for that f-stop.

The idea is to focus on the most important distance in the scene. Merklinger notes that stuff at infinity—if you are focused to hyperfocal distance—isn't sharp at close inspection, which makes sense

Really, you have to stand back from your print or image—at least one diagonal image width away—in order to *not* see the blur at infinity, and that's only if you have 20/20 vision, and plenty of people have better than that. And nowadays, with huge prints and pinch and zoom viewing of images on mobile devices, out of focus blur is likely more visible than in days past.

If you want infinity to be sharp, then focus at infinity. Many landscape photos have nothing but details at infinity. I see a common problem with beginners shooting hyperfocal distance, where there is nothing whatsoever in the image that is in front of the hyperfocal distance, and their images look blurry.

 Mark S Abeln's gear list:Mark S Abeln's gear list
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Klaus dk
Klaus dk Veteran Member • Posts: 8,942
Re: Usability of Zone Focusing

Gurusathiy wrote:

Klaus dk wrote:

It's scary and probably even stupid to disagree with Zeiss on anything optics, but I'd say the first direction is correct: Set the infinity mark at the rightmost f-stop mark to set the lens to hyperfocal distance for that f-stop.

As everybody else have pointed out, these are FF lenses, and your camera is APS-C, so you have a deeper DoF.

There are some caveats, though. First, the CoC depends on the medium and the expected usage. A high resolution APS-C sensor would have a smaller CoC than a fast negative film, for instance, and a wall sized print viewed close up demands a very small CoC, if you want it "pin sharp".

And I'll also repeate what others have written: There Is No Set And Forget Focus Setting. If you want phone functionality, use a phone.

I support the suggestion for a solid tripod. I've found reading Thom Hogan's considerations worth while.

Good luck and good light.

hi Klaus,

Thanks for the inputs, I've to convince myself that there is no shortcut to my conundrum.. One thing I want to understand is on CoC.. if as per hyperfocal I set infinity to f/8.0 mark for taking aperture (we'll keep aside crop factor for now), where does this CoC will come into play? Is that subject distance changes or focus distance changes (in case if its just a scenery) as per math on CoC to ensure sharp images?

Helpful people have already explained about The Circle of Confusion as it relates to depth of field.

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Mark S Abeln
Mark S Abeln Forum Pro • Posts: 18,900
Show us photos

Gurusathiy wrote:

Thanks for the inputs, I've to convince myself that there is no shortcut to my conundrum.. One thing I want to understand is on CoC.. if as per hyperfocal I set infinity to f/8.0 mark for taking aperture (we'll keep aside crop factor for now), where does this CoC will come into play? Is that subject distance changes or focus distance changes (in case if its just a scenery) as per math on CoC to ensure sharp images?

As Klaus wrote, there is plenty of information online about the *definition* of CoC, and yes, it comes into play.

But the Circle of Confusion has plenty of non-objective factors: including the subjective factor of your eyesight—the equation *assumes* you have 20/20 vision—and the relative factors of your print size and your viewing distance, and the equation *assumes* you are viewing the image from a distance equal to the diagonal width of the image. If even one of these assumptions is incorrect, then the circle of confusion is also incorrect.

Instead of spending time trying to explain abstract reasoning, it would likely be better if you show us a few of your disappointing photos, unedited and straight out of the camera, along with your focus distance if you remember. Your problem may be completely unrelated to depth of field.

 Mark S Abeln's gear list:Mark S Abeln's gear list
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Bob
Bob Veteran Member • Posts: 3,997
Re: Solving the wrong problem

Do you use a tripod when you magnify for MF?

SmilerGrogan Senior Member • Posts: 1,329
empty post

.

OP Gurusathiy Junior Member • Posts: 25
Re: Show us photos

Mark Scott Abeln wrote:

Instead of spending time trying to explain abstract reasoning, it would likely be better if you show us a few of your disappointing photos, unedited and straight out of the camera, along with your focus distance if you remember. Your problem may be completely unrelated to depth of field.

hi Mark,

Appreciate your patience in taking time to reply and help me!! The lens is with my friend now, will grab it over the weekend and come back here with pics to learn more!!

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Thanks
Guru raj

OP Gurusathiy Junior Member • Posts: 25
Re: Solving the wrong problem

hi Bob,

It is handheld, mostly with speeds exceeding 1/250s.. Only for speeds requiring long exposure (aka waterfalls milky effect), I use tripod!!

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Thanks
Guru raj

OP Gurusathiy Junior Member • Posts: 25
Re: Usability of Zone Focusing

Thanks Klaus, will check more on CoC..

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Regards,
Guru raj

OP Gurusathiy Junior Member • Posts: 25
Re: Solving the wrong problem

Jessica M wrote

One of the reasons I’m struggling with your question is that you want ‘critical sharp’ using techniques for ‘sharp enough’. The thing you’re asking is not possible.

hi Jessica,

Thanks for the revert, exactly the problem I've at hand - something not possible.. I've understood that from all the expert inputs in this thread! Now on next steps - share pic and understand what I can do better to make taking pics more enjoyable and faster (importantly)!!

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Regards,
Guru raj

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