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Author Topic: Practical Depth of Field in the field  (Read 6698 times)

bobtrlin

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Practical Depth of Field in the field
« on: July 18, 2016, 05:43:51 am »

If this has been dealt with before, please steer me in the right direction, I'm a newbie to the site.  DOF is the bane of my life.  Like most on this site, I understand the principles.  I understand that DOF is subjective and I understand the concept of circle of confusion.  What I would like to know is what goes on in the experts' heads in the field when thinking of getting the DOF right.
The techniques I'm aware of are:
 1. Practice practice till you get it right or as a pro would say, practice till you can't get it wrong - time consuming
 2. Use DOF tables - complex particular for zooms
 3. Use a smartphone app - difficult to read in bright sun
 4. Use a DOF calculator - same a 2 above
 5. DOF preview button - too dark on SLR's, better but still difficult to see with EVF's

With the wealth of information presented in the modern viewfinder, it beats me why they can't give some guidance to DOF either numerically or perhaps with some form of peaking display.
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razrblck

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Re: Practical Depth of Field in the field
« Reply #1 on: July 18, 2016, 05:55:24 am »

If I try to maximize depth of field (like in landscapes) I always focus either on some feature I want to have perfectly sharp, or focus at infinite and dial it back manually a tiny bit (usually to get it in the 30m range). The stuff that is very very far won't be in focus anyway unless you have a very clear day without humidity (which is rare) so it's better to keep the things that matter inside the sharpest area.

For everything else I choose aperture more based on how much light I need and how much background I want to blur rather than thinking about DOF. There are instances you need to take it into account, like a portrait with a very fast tele as you'll have to stop down to make sure the face is not a blurry mess. That also depends on more aesthetic factors as if you close the aperture too much you might get a distracting background, so it's always better to play around and actually see the result.

Calculations can only get you that far, experience will definitely help you the most especially if you can visualize everything else that goes with changing DOF in your scene.
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graeme

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Re: Practical Depth of Field in the field
« Reply #2 on: July 18, 2016, 06:27:48 am »

Using magnified Live View I focus on the part of the image I feel is most important, then press the DOF preview button & scroll around the magnified image checking what's acceptably in or out of focus then adjust focus or aperture accordingly. ( But I'm not sure I'd describe myself as an expert ).

The Infinity Focus method described here may also be of interest:

https://luminous-landscape.com/digital-focusing-part-two/?s=Gary+Ferguson
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ErikKaffehr

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Re: Practical Depth of Field in the field
« Reply #3 on: July 18, 2016, 01:51:36 pm »

Hi,

My approach is a bit:
  • Focus at the essentials
  • Don't care about the rest
  • Stop down as needed
  • Use focus stacking (works sometimes) or Scheimpflug (works sometimes)
  • Forget about DoF tables

Best regards
Erik

If this has been dealt with before, please steer me in the right direction, I'm a newbie to the site.  DOF is the bane of my life.  Like most on this site, I understand the principles.  I understand that DOF is subjective and I understand the concept of circle of confusion.  What I would like to know is what goes on in the experts' heads in the field when thinking of getting the DOF right.
The techniques I'm aware of are:
 1. Practice practice till you get it right or as a pro would say, practice till you can't get it wrong - time consuming
 2. Use DOF tables - complex particular for zooms
 3. Use a smartphone app - difficult to read in bright sun
 4. Use a DOF calculator - same a 2 above
 5. DOF preview button - too dark on SLR's, better but still difficult to see with EVF's

With the wealth of information presented in the modern viewfinder, it beats me why they can't give some guidance to DOF either numerically or perhaps with some form of peaking display.
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Erik Kaffehr
 

bobtrlin

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Re: Practical Depth of Field in the field
« Reply #4 on: July 18, 2016, 08:03:09 pm »

This site does not appear to have a "thanks" button so to razrblck, Graeme and ErikKaffehr above, thanks.  You have given me some great ideas to go on with.  This is exactly what I wanted.
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armand

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Re: Practical Depth of Field in the field
« Reply #5 on: July 18, 2016, 09:36:52 pm »

Fujifilm has this, you can see the DOF on the bottom of the screen:

bobtrlin

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Re: Practical Depth of Field in the field
« Reply #6 on: July 19, 2016, 04:50:23 am »

Fujifilm has this, you can see the DOF on the bottom of the screen:
Excellent!  I lament the disappearance of DOF scales on so many modern prime lenses.  I used to use them all the time.
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dwswager

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Re: Practical Depth of Field in the field
« Reply #7 on: July 19, 2016, 09:31:04 am »

As an engineer, I revisit this topic regularly.  It does not help that I am now older and require reading glasses for close in.

It is good practice to have a general idea of DoF for focal length and apertures before ever going in the field.  This is not for precision, but to quickly eliminate options.  For example, you can look at a scene and the light and the focal length and just say "it ain't gonna happen" and move away from trying to get everything in relatively sharp focus and position the DoF to where you want it.

Using the viewfinder:  I use a magnifying eyepiece on my Nikon D810 to help and I still have a dark cloth that I can shield my viewfinder/eye with in bright sunlight to use the DoF.  Takes a few seconds for your eye to adjust to the reduced light but it works.

Live View:  The magnification option of live view is fantastic for this.  However, you will still want the dark cloth or some purpose built shade/hood for the screen when in bright light.

And Armand hit on my biggest peave with camera manufacturers.  I won't generalize, but as I Nikon shooter, every single modern Nikon with a "D" model lens or newer on it knows the Focal Length, Aperture and current focus distance and could report to the user the Near Focus Point, Far Focus Point and the hyper focal distance.  There should be CoC setting in the camera for the user to choose.
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bobtrlin

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Re: Practical Depth of Field in the field
« Reply #8 on: July 20, 2016, 05:23:00 am »

I won't generalize, but as I Nikon shooter, every single modern Nikon with a "D" model lens or newer on it knows the Focal Length, Aperture and current focus distance and could report to the user the Near Focus Point, Far Focus Point and the hyper focal distance.  There should be CoC setting in the camera for the user to choose.
Totally agree!  BTW, I'm also an engineer, retired.  I don't have glasses anymore.  I now have intraocular lenses.  The left eye set for reading and the right for distance.  It takes a bit for the brain to work that out.  It works sort of but depth perception is not the best.  I have no trouble using my right eye for pics but I can't throw ball with my son anymore or risk getting beaned.
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AFairley

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Re: Practical Depth of Field in the field
« Reply #9 on: July 21, 2016, 12:38:26 pm »

Fujifilm has this, you can see the DOF on the bottom of the screen

But notoriously to somewhat inaccurate on my X-E2 with my 18mm f2, 27mm and the 18-55 zoom, so I would not rely on it without testing.
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Paulo Bizarro

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Re: Practical Depth of Field in the field
« Reply #10 on: July 25, 2016, 11:36:48 am »

This is why I like my Zeiss Batis 25 very much, with its electronic reading of the minimum and maximum focusing distances. I just dial in the aperture I want (say f11 or f16), and then slowly manually focus until the infinity symbol shows up on the right hand side of the reading. Works like a charm.

Canon used to have an "idiot" DOF mode on their film cameras, whereby you would focus on the closest and farthest points that you wanted to be "in focus". The camera would then select the aperture.

All of this stuff should be easy to do today. Of course it requires some testing to see what calibrations have been used, but we used to test also with the manual DOF scales in the past, for our lenses.

mbaginy

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Re: Practical Depth of Field in the field
« Reply #11 on: July 25, 2016, 03:38:47 pm »

For what it's worth, Rumor Control has it, that a Canon zoom will be produced with a digital DOF display shortly: cannonrumors
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dwswager

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Re: Practical Depth of Field in the field
« Reply #12 on: July 25, 2016, 09:13:07 pm »

All of this stuff should be easy to do today. Of course it requires some testing to see what calibrations have been used, but we used to test also with the manual DOF scales in the past, for our lenses.

Yes, it should.  And you always need to calibrate.  And a simple in camera setting for CoC would be nice.   Modern cameras could be "app" running machines.  Helicon Remote built in...
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BobShaw

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Re: Practical Depth of Field in the field
« Reply #13 on: July 25, 2016, 10:35:52 pm »

Hi,

My approach is a bit:
  • Focus at the essentials
  • Don't care about the rest
  • Stop down as needed
  • Use focus stacking (works sometimes) or Scheimpflug (works sometimes)
  • Forget about DoF tables

Best regards
Erik
+1. I have never used a depth of field table in the wild. If doing landscapes get a tilt shift lens.
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