Distance and Depth of Focus numbers while shooting

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

I got nuthin’ … I just tried every playback setting on my Z8 and it doesn’t show either distance or DOF.

Remember though that DOF is somewhat subjective… it is the area of “acceptable focus.” Define “acceptable.”

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

The best approach to getting an indication of depth of field is to use focus peaking. Sensitivity of 2 (the middle setting) provides a good indication of DoF.

JA_Johnson said:

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

The best approach to getting an indication of depth of field is to use focus peaking. Sensitivity of 2 (the middle setting) provides a good indication of DoF.

Click to expand...

Focus Peaking accuracy is dependent on the lens focal length.

And it depends on the target area contrast/texture for how wide the range of red is showing.

I find it difficult to get the red band depth to match with very good sharpness areas. It's often lighting up areas that aren't in acceptable focus.

It does work very well for centering the band of focus where I want it -- the center of the band is a stronger red. I do usually leave it at Peak 2.

Z6 iii, 24-120 at f/4. Focusing on a ruler at a 30 degree angle, from arm's length:

Peak 1 Low Sensitivity (the narrowest band of red -- it's high accuracy, via low sensitivity.)

at 24mm: A lot of red peaking, even including outside of the sharpest range when zoomed in on image review.

at 120mm: it's difficult to see the red peaking, there's often just a few red dots. This 120mm view does have a quite narrow depth of focus.

~~~

Peak 3 High sensitivity (the widest band of red)

at 24mm: the red band includes some obviously not-in-focus areas, even when viewed on the rear screen while composing the shot.

at 120mm: the red band is pretty close to the reasonable focus areas. In image review, zoomed to 100%, the red band is still wider than the excellent focus areas.

~~~

Switching peaking 1,2,3 is easy with the i-menu. the rear command dial controls peaking on/off, and the front command dial controls level 1,2,3.

jthomas39 said:

JA_Johnson said:

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

The best approach to getting an indication of depth of field is to use focus peaking. Sensitivity of 2 (the middle setting) provides a good indication of DoF.

Click to expand...

Focus Peaking accuracy is dependent on the lens focal length.

And it depends on the target area contrast/texture for how wide the range of red is showing.

I find it difficult to get the red band depth to match with very good sharpness areas. It's often lighting up areas that aren't in acceptable focus.

It does work very well for centering the band of focus where I want it -- the center of the band is a stronger red. I do usually leave it at Peak 2.

Click to expand...

I have focus peaking set to use blue instead of red because blue colors are more easily detected to my eye. Focus peaking isn’t perfect but set to 2 it offers a good approximation of depth of field, in my experience.

A monochrome picture profile can improve the perception of peaking, especially with a shallow DOF.

Otherwise, it's simply a matter of gaining experience.

In other words, frequent use of the Z 85/1.8 S.

Apart from that, there are various DoF, hyperfocal distance, and bokeh size calculator apps for mobile phones if you want specific figures/reference values.

Otherwise, you can also visit websites to get an basic idea of how DoF works/scales for certain focal length/aperture combinations and how the distance to the subject affects it.

https://dofsimulator.net/en/

A minor detail with focus peaking – it detects only detail parallel to the short dimension of the frame – and does not detect detail parallel to the long dimension of the frame.

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

I don' think you can when you're shooting. That being said, on some of the premium lenses that have the top LED, you can get some DOF info from digital scale on the LED if I remember correctly, but it's only on those lenses that have an LED window (so the Z 70-200, Z 24-70 2.8 S, among others with the little window, but for every other lens, I don't think you can).

In manual focus mode, there is a scale that shows up but I found this to not be very useful.

Clearly, the lenses are able to help communicate this info to the body (if we look at the ones I mentioned above like the 70-200) so I don't know why Nikon cannot have an option to display this info in the LCD at least when focusing (could be added via firmware). I also wish they would add the ability to see the focal length in the EVF/LCD as well.

--
* PLEASE NOTE: I generally unsubscribe from forums/comments after a period of time has passed, so if I do not respond, that is likely the reason. *

sirhawkeye64 said:

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

I don' think you can when you're shooting. That being said, on some of the premium lenses that have the top LED, you can get some DOF info from digital scale on the LED if I remember correctly, but it's only on those lenses that have an LED window (so the Z 70-200, Z 24-70 2.8 S, among others with the little window, but for every other lens, I don't think you can).

In manual focus mode, there is a scale that shows up but I found this to not be very useful.

Clearly, the lenses are able to help communicate this info to the body (if we look at the ones I mentioned above like the 70-200) so I don't know why Nikon cannot have an option to display this info in the LCD at least when focusing (could be added via firmware). I also wish they would add the ability to see the focal length in the EVF/LCD as well.

Click to expand...

The 105 MC has this display, but the DOF indication is almost useless. DOF is tiny anyway in the macro range. It is better to inspect the generated image.

The 85mm f/1.8 has a small DOF too in almost any setting. It's the purpose of this lens to isolate subjects. I too think experience is a better guide than any scale.

That's how I see it too, you develop a feeling all by yourself over time if you use a 85mm f/1.8 extensively.

If a focal length/speed combination is completely new, it can be very helpful in the beginning to photograph the same scene consistently with different aperture settings.

This helps you to get a feel for the lens and the appropriate DoF/aperture settings for different scenarios and distances much more quickly.

But it is also clear that the DoF at f/1.8 and 85mm can be very thin, especially if you are shooting portraits, headshots, half body shots, close distances where stopping down is often more.

For full body portraits, f/1.8 is much more suitable.

But of course it's a question of taste and personal style.

In very special cases, as already mentioned, there are apps that spit out details, for example if you want to work with hyperfocal distance or want to determine the optimum DOF range for a particular shot very precisely.

In everyday practice, it is experience that makes the choice of the most suitable aperture for the situation intuitive.

Rene Gr said:

sirhawkeye64 said:

Carpetrunner said:

Hi All,

The 85f1.8s is my first real portrait lens, on a mirrorless body (Zf). I've been shooting wide open, loving it, and wanting to better understand and control the DoF.

I can see the EXIF data (exiftool-13.17) has focus distance and DoF;

Focus Distance : 1.38 m
Depth Of Field : 0.03 m (1.37 - 1.40 m)

I can fudge the subject distance by nudging the focus ring after it has autofocused.

Does anyone know a way to get the Dof information in the display while shooting?

thanks,

Carpetrunner

Click to expand...

I don' think you can when you're shooting. That being said, on some of the premium lenses that have the top LED, you can get some DOF info from digital scale on the LED if I remember correctly, but it's only on those lenses that have an LED window (so the Z 70-200, Z 24-70 2.8 S, among others with the little window, but for every other lens, I don't think you can).

In manual focus mode, there is a scale that shows up but I found this to not be very useful.

Clearly, the lenses are able to help communicate this info to the body (if we look at the ones I mentioned above like the 70-200) so I don't know why Nikon cannot have an option to display this info in the LCD at least when focusing (could be added via firmware). I also wish they would add the ability to see the focal length in the EVF/LCD as well.

Click to expand...

The 105 MC has this display, but the DOF indication is almost useless. DOF is tiny anyway in the macro range. It is better to inspect the generated image.

The 85mm f/1.8 has a small DOF too in almost any setting. It's the purpose of this lens to isolate subjects. I too think experience is a better guide than any scale.

Click to expand...

Yes I'd agree, OR using a program like PhotoPills to calculate it. I've also found on some lenses (older lenses) that the DOF scales and focus distance scales can be off slightly and not entirely accurate (particularly the infinity markings). I mainly use PhotoPills these days for calculating DOF when I'm not sure or to double check.

This is one taken with f/1.8 on the 85mm. My feeling is that the DOF is too thin. I prefer f/2.8. But we are digressing from the topic.

Thanks everyone, maybe I just miss the AI-S lens markings. I would have thought that the Zf would be a golden opportunity to reproduce some retro lens markings in the viewfinder ;-)

Anyway, I will use the lens more and play with focus peaking - agreed experience is the best teacher.

I just need to remember DoF is squared for distance and doubled for aperture and I'll be OK. Starting at 1m, f1.8 is a DoF of 1cm for an 85mm.

As a rule of thumb I'll try to remember;



This probably means no closer than 2 meters/yards when wide open unless I'm attempting art.

- carpetrunner

Rene Gr said:

This is one taken with f/1.8 on the 85mm. My feeling is that the DOF is too thin. I prefer f/2.8. But we are digressing from the topic.

Click to expand...

Hi Rene, Thanks,

Can you remember the distance that this was taken at? The focus distance isn't in the EXIF. I'm guessing the DoF is around 5cm that would put the subject distance just less than 2m?

- carpetrunner

Around 1.6 m distance. My son took that with my camera. Single person shots look good at f/2.8 or f/4. It is almost impossible to make bad portraits with the 85mm. The problems start with two persons. If you want to have both in focus, the 50mm is the safer lens at f/5.6.

PLShutterbug said:

[snip]

Remember though that DOF is somewhat subjective… it is the area of “acceptable focus.” Define “acceptable.”

Click to expand...

You've hit the nail on the head!

Unfortunately, any DoF or Hyperfocal Distance calculator (E.g.: PhotoPills) that relies on your camera make and model (sensor dimensions), has a high probability of producing disappointing results, because three huge assumptions are made:

1. Everyone using that size sensor will routinely apply the exact same Enlargement Factor...
2. ... for the exact same Viewing Distance...
3. ... with an identical expectation of "acceptable sharpness" at the Near and Far limits of DoF.

That's ridiculous, but there are web apps and mobile apps designed to calculate DoF or Hyperfocal Distance or even the f-Number at which Diffraction will become an issue, while making those assumptions, asking only for your camera make and model (or sensor size) - as if all users of a given sensor size have the same needs and expectations.

These apps have all APS-C shooters calculating DoF with a CoC diameter of 0.02mm, all fullframe shooters using a 0.03mm CoC (just like the DoF scales engraved on 20th-century, manual-focus lenses of 35mm format SLRs ), etc. This broad stroke of one-size-size-fits-all ambiguity, combined with a lack of accuracy in the field, when measuring the Near distance (an input to the very trustworthy equation used for calculating DoF) and a lack of accuracy with focusing at the calculated distance (an output), are why so many people do not trust such calculations.

And this begs the question, "What CoC Diameters are being applied when any camera manufacturer's focus peaking settings are adjusted?" They don't document this. The effect shown in the EVF varies with trustworthy FL, as expected, but focus peaking becomes no more relevant to an individual photographer's expectations than the DoF scales engraved on manual-focus lenses. We're forced to do a lot of backyard testing to determine which focus peaking setting comes closest to delivering a personally relevant simulation of what any one photographer will see when examining the final image at the anticipated enlargement factor and viewing distance - the only place where the very subjective assessment of "acceptable sharpness" can be made.

These problems are easily fixed:

1) Calculate a personalized Maximum Permissible Circle of Confusion Diameter that incorporates your anticipated Maximum Enlargement Factor, your anticipated Minimum Viewing Distance, and YOUR well-quantified, Desired Final Image Resolution.

See the Max. CoC equation in this article:
https://en.m.wikipedia.org/wiki/Circle_of_confusion

2) Use a DoF or Hyperfocal Distance calculator that permits direct user entry of the customized Maximum Permissible CoC Diameter. (This will eliminate all of the aforementioned assumptions that come with using default CoC values, that are based solely on sensor dimensions).

3) Buy and use a small and lightweight laser distance measure for Near and Focus Distances. I strongly recommend the Bosch GLM165-40 Blaze™ (under $100 at Amazon and elsewhere). It's actually fun to use, allowing quick and accurate measurements.

4) Learn how to setup and use Back Button Auto-Focus on your camera, which allows you to quickly and accurately focus on a subject that resides at the DoF app calculated and laser measured focus distance, for the FL and f-Number indicated by those calculations, LOCKING the focus at that distance, prior to reframing your composition.

I sometimes have to remove the camera from the tripod to place it at the laser measured distance from a suitable object that was not in the frame (as when shooting at the shore of a body of water, where the hyperfocal distance is out on the surface of the water, somewhere. LOL) Having locked the auto-focus at the calculated focus distance, you can return the camera to the tripod and go.

This approach will secure your well-quantified definition of "acceptable sharpness," to record nominally sufficient DoF while also using the widest possible apertures for the shortest possible exposures and lowest possible ISO settings, for any given subject space, until that range of distances would force the use of an f-Number that induces visible diffraction across the entire frame - at which point, you can move the camera farther away from the Nearest subject, go to a shorter focal length, or willfully decide to reduce your intended enlargement factor, so that you don't have to compromise your (subjective) Desired Final Image Resolution - or some combination of those three options - which require remeasuring and recalculating your DoF, to obtain a new f-Number and Focus distance.

This method requires doing a little bit of homework with a four-function calculator and some discipline in the field. Note that it takes less than a minute to accurately measure your Near distance, then set your aperture and lock your focus at the correct distance, using the laser distance measure and Back Button Auto-Focus - extending to perhaps two minutes if you have to find a suitable target on which to lock the focus, that resides outside your framed composition. I've been doing this for almost twenty years, beginning with Mamiya 7ii medium format bodies, shooting 3D image pairs.

If anyone has questions about coming up with a personalized Maximum Permissible CoC Diameter (as covered in the Wikipedia article, linked above), that can be used with the very few applications that permit direct entry of a CoC value (E.g. DoFMaster), feel free to ask.

Mike Davis said:

1. ... for the exact same Viewing Distance...
2. ... with an identical expectation of "acceptable sharpness" at the Near and Far limits of DoF

Click to expand...

On the assumption the subject is about depth of field rather than depth of focus; Historically using Kodak in the late 1970's as a starting point depth of field has been based on what is considered just acceptably sharp on the assumption that a 10x8 inch print made from the whole of the image area and viewed at a comfortable viewing distance of about 15 inches with normal eyesight is a reasonable standard.

How precisely this equates to the .03 mm CoC often used by camera manufacturers, often in depth of field tables, or the old Kodak standard of 1/100 an inch edge blur being just acceptable is rarely clarified.

Any photographer is free to choose whether or not .03 mm reasonably identifies for them the boundary between sharp and unsharp based on viewing a 10x8 inch print from the whole of the image area, or at a proportionately greater distance for larger print sizes. I consider the 0.03mm standard to be a reasonable starting point.

EDIT - prior to about year 2,000 Nikon generally provided depth of field tables for most focal lengths based on 0.03 or 0.033mm END OF EDIT.

When images are likely to be particularly closely inspected as when used for police/court evidence it is common to work to stricter Depth of Field standards than 0.03mm.

Technically depth of focus - the permissible deviation either side of the film or sensor surface before taking a picture - is different to the zone of acceptable sharpness as in depth of field when viewing an image after taking a picture.

--
Leonard Shepherd
In lots of ways good photography is similar to learning to play a piano - it takes practice to develop skill in either activity.

Leonard Shepherd said:

[snip]

Any photographer is free to choose whether or not .03 mm reasonably identifies for them the boundary between sharp and unsharp based on viewing a 10x8 inch print from the whole of the image area, or at a proportionately greater distance for larger print sizes. I consider the 0.03mm standard to be a reasonable starting point.

[snip]

Click to expand...

Thanks for your reply!

I agree with everything you've said, but would like to add that, even though photographers are "free to choose whether or not 0.03mm" is satisfactory for their needs and expectations, most DoF applications deprive users of that freedom and offer no apologies or explanation for often disappointing results.


Most of today's DoF apps (E.g. PhotoPills) do not allow direct entry of a personally relevant Maximum Permissible CoC Diameter. Instead, they require users to select a camera make and model, which the apps translate into an ambiguous, default CoC Diameter, that's based solely on their camera's sensor size - as if all photographers using that size sensor have identical needs and expectations for Enlargement Factor, Viewing Distance and... Desired Final Image Resolution.

In other words, with most of today's DoF or Hyperfocal Distance apps, the freedom of which you write can only be had by "guessing" which camera make and model might be selected to deliver more suitable results - which is akin to how many photographers using manual-focus lenses equipped with engraved DoF scales, might conclude that they always have to stop down one more stop than indicated, for example.


And even if a photographer makes use of an app that permits direct entry of a CoC Diameter, if the photograher has not taken the time to calculate a personally relevant CoC Diameter, that takes into consideration the photographer's Anticipated Maximum Enlargement Factor, Anticipated Minimum Viewing Distance, and a very subjective, but easily quanitified value for Desired Final Image Resolution, whatever CoC value they arbitrarily pluck from thin air, will leave them performing lots of trial-and-error testing (fraught with error, if not accurately measuring your Near and Focus distances).


It's not hard to use a four-function calculator to come up with that personally relevant Maximum Permissible CoC Diameter, which takes those unique factors into consideration.

Equipped with a customized CoC Diameter, then using it in one of the rare DoF apps that actually permit user-specification of a custom CoC diameter (E.g. DoFMaster), the photographer must then exercise some discipline with accurately measuring the Near distance and the calculated Focus distance, with the nominally required f-Number, for the FL in use.


Hint: Using a laser distance measure, plus Back Button Auto-Focus readily facilitates this.

When examining the results (not in the camera's EVF, but at the originally intended Maximum Enlargement Factor and Minimum Viewing Distance (be that with a print, a backlit transparency, a 4K monitor, or whatever), the photographer can always modify the third personalization factor, Desired Final Image Resolution (expressed in lp/mm for a 25cm viewing distance, even if the anticipated viewing distance is greater than 25cm), to either increase or decrease their Desired Final Image Resolution, as they see fit.

Most fullframe shooters are not content with the seemingly universal, 0.03mm CoC diameter, except by happenstance, any more so than users of 35mm format SLRs were content with that hard-coded value.


I would like to see fewer DoF apps perpetuating the "acceptable sharpness" convention established long ago by lens manufacturers (0.03mm for fullframe, 0.06mm for MF, etc.) - a convention that has countless people today, expressing a lack of trust in DoF and Hyperfocal Distance calculations.

The physics haven't changed - only the understanding of what's necessary to make use of the very trustworthy equations.

https://en.wikipedia.org/wiki/Circle_of_confusion

--
Mike Davis
http://www.accessz.com

Mike Davis said:

Most of today's DoF apps (E.g. PhotoPills) do not allow direct entry of a personally relevant Maximum Permissible CoC Diameter.

Click to expand...

One "quick fix" is to use 1 stop wider than 0.03 predicts.

Another more demanding technique is to zoom to 200% (or 400% if available) on the rear monitor and, based on personal experience and personal standards, to use this as a basis for DoF sharpness boundaries.

A third option most commonly found in advanced video set-ups is to take decisions based on viewing using an around 6 inch display feeding directly from the image while shooting for a usefully larger display size than using a camera rear monitor or viewfinder.

Mike Davis said:

(snipped)

I would like to see fewer DoF apps perpetuating the "acceptable sharpness" convention established long ago by lens manufacturers (0.03mm for fullframe, 0.06mm for MF, etc.) - a convention that has countless people today, expressing a lack of trust in DoF and Hyperfocal Distance calculations.

The physics haven't changed -

Click to expand...

I agree the physics have not changed.

Few I hope dispute the quality and resolution achievable with current good quality digital equipment is dramatically higher than in the relatively early days of 50 years ago when Kodak was a pioneer in codifying what were at the time reasonable standards.

Clearly you set your own standard, just as I set mine.

Both of us seem conscious that a one size fits all "number" can be OK some of the time, though it is unlikely to be right in all shooting scenarios all of the time.

Which Plena effect (below) anyone prefers is personal choice.

Almost all PP software shows the aperture used.




Test of Plena at f5






Test of Plena at f1.8.





--
Leonard Shepherd
In lots of ways good photography is similar to learning to play a piano - it takes practice to develop skill in either activity.