Depth of View preview

[AlwaysOnAuto]

Merry Christmas all!

[dem]

Interesting that it does not work like that on my Panasonic GX7; it shows the same area, regardless of what aperture I select. It looks like different manufacturers have implemented focus peaking differently.

There might be a menu option to stop the aperture down while focusing instead of always using the widest aperture:

https://www.dpreview.com/forums/thread/3616375

Also, how about manual lenses? If aperture is controlled by the aperture ring on the lens rather than electronically by the camera, it should work.

[Manfred M]

There might be a menu option to stop the aperture down while focusing instead of always using the widest aperture:

https://www.dpreview.com/forums/thread/3616375

Also, how about manual lenses? If aperture is controlled by the aperture ring on the lens rather than electronically by the camera, it should work.

I got the same results with a manual lens. The peaking showed the same in-focus area when stopped down to f/16 as when all the way open at f/2. I could definitely see the viewfinder darken when I stopped down.

With respect to the menu controls, I can turn the peaking off and on, I can change the peaking colour and I can change the sensitivity of peaking to high or low.

Frankly, this is the way I would expect focus assist to work as what is critical to me is identifying the in-focus areas as defined by the focus plane. Giving me a DoF overlay is less useful because I still want to ensure that my focus is where I want it.

[xpatUSA]

This is what you said:



If we use these subject-camera distances for the respective focal lengths and calculate DoF at f/5.6 on a full frame camera (CoC =0.03mm) using

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

we get 81.7mm for a 50 mm lens and 93.1mm for a 105mm lens.

There is a 11.4 mm difference which is there because I used your value of 1792mm which presumably was calculated from the sensor plane. If we calculate the camera-subject distance for a 105mm lens as 800 / 50 * 105 = 1680 mm (i.e. all distances are measured from the lens's optical centre), DOF calculator gives 81.5mm. Close enough to 81.7mm?


That is exactly the regime where the DOF is a function of framing alone. Once the focusing distance gets close to the hyperfocal, then this rule doesn't quite work anymore.

EDIT. Ted, have you tried comparing your spreadsheet data to

https://www.photopills.com/calculators/dof-macro

To obtain the target magnification of 1:15 with a 50 mm lens, this calculator requires a sensor-subject distance of about 853mm (DoF = 81.39mm) and for a 105 mm lens it requires a sensor-subject distance of about 1792mm (DoF = 81.46mm). This is at f/5.6 and default values for full frame CoC and pupil magnification of 1. There is a few mm uncertainty in the sensor-subject distance due to the round up error for the magnification.

So for fixed framing/magnification two different websites predict the same DoF of about 81.5mm for either a 50mm or a 105mm lens.

Thanks Dem, out of town at relatives, so I'll have to dig later into my spreadsheets - one for magnification - one for distance. Both are based on an interesting paper by Richard F Lyon:

http://kronometric.org/phot/iq/DepthOfField-Lyon.pdf

Maybe there is a fundamental error in both spreadsheets because my numbers work both ways betwixt the two.

I'll get back to you later this week (today is Sunday here).

[miatab]

Where is Catherine in all this? What of her original post? I get the impression you people don't care. Why do I get that impression?

[Stagecoach]

Where is Catherine in all this?

Catherine has reacted to all relevant posts and personally I believe her knowledge and understanding shown in both previous threads and this one demonstrate she is learning well and participating fully.

What of her original post?

I just read about the DOV preview feature. My camera doesn’t have it, maybe because it is a bridge camera but I’m not sure. Do most cameras have this?

It seems a big advantage to mirrorless cameras that what you see in the viewfinder is what you will get.

I believe there have been a number of helpful answers/tips in response to these and as always a couple of off track ones that I'm sure Catherine is knowledgeable enough to recognise they are not applicable to her situation/camera.

I get the impression you people don't care.

Personally I did my utmost to assist with advice as well as some others with specific reference to her thread and questions.

Why do I get that impression?

I have absolutely no idea other than it could be because you have not been able to find the "answers" within all that has been written.

[Manfred M]

Where is Catherine in all this? What of her original post? I get the impression you people don't care. Why do I get that impression?

If you look through the history of the posts, Catherine has been very much involved in a two way conversation on the value and use of this functionality. I can't read her thoughts, but get the impression she feels that her question was answered.

As with many other threads, it did wander off the original question a bit, but these questions and answers were still more or less on topic and people responded to follow up questions in a courteous manner. That seems to be the nature of many of the threads and as long as the responses are related to the topic and don't go too far off the rails, I see no issue at all with these developments. After all CiC is primarily about learning about photography.

[CatherineA]

Good morning Ken, Grahame and Manfred! And, if you celebrate it, Merry Christmas too!

Ken- It is true that I stopped responding to individual posts and I think that has ended up giving a misleading impression and i am sorry about that.

I am so grateful and appreciative of advice that I receive here. I am a beginner and my questions are basic and yet people who are incredibly talented and knowledgeable about the science of this wonderful art give their time and encouragement and respect to me. I’m embarrassed by some of my posts (such as the time I posted that we were going to have a super moon here in Ottawa. I mean, what the heck did I think the moon was up to in the rest of the world?) but I’ve always been treated with consideration no matter what I’ve said or asked.

I felt that my post had been answered and then the conversation went on to a level that I can’t fully benefit from at this stage. That’s ok: I‘m glad to have all the posts and I am glad that I will be able to easily access this thread in the future when I can benefit from all of it. Perhaps I should have posted that.

Grahame - You have done your utmost to assist me with advice so many times now. I used to tell my family that the ‘very nice person from Fiji’ answered my question again and now they say, “you mean Grahame with an ‘e’ .”

[William W]

Oh dear, Bill...

I've just posted quite the opposite here: . . etc . . . Clearly my spreadsheet mentioned therein is badly at odds with your statement and I'm not sure why that is. . . .

(From Link)

I have a spread-sheet for macro work that takes an input of magnification, based on object size and how much of the sensor it occupies. For instance, it tells me for 300mm, 20mm at f/5.6:\
f-length: distance, DOF
50mm: 800mm, 75mm
105mm: 1792mm, 157mm

Maybe because the object in the shots was at much less than the hyperfocal distance?

Hello Ted, Merry Christmas to you, too.

(There seems error in your calcs, please firstly refer to Dem's Post #34)

*

However you did sort of nailed it.

The Axiom of DoF to which I referred, I believe does not apply to Macro (1:1) and Micro (greater than 1:1) Photography or ("really close") Close-Up Photography, with for example CU Filters.

*

The Axiom is MOST applicable at typically common Shooting Distances for most general photography and usually this is where DoF may be considered as a relevant Artistic Factor, for example Portraiture; but the Axiom still hold reasonably for the Subject Distances that Catherine would be using for her Wildlife Photography; although as Dem mentioned it does fall off a bit at and beyond the Hyperfocal Distance

I have mentioned this Axiom a few times here at CiC - I found it very useful in a practical application for most of my Professional Shooting for Weddings and Candid Portraiture; which resulted many years ago me making this type of Cheat Sheet (this one is applicable only to 135 Format: an individual CS is required for each different camera format):



One element to notice is the Pattern of Numbers - which makes this type of CH easy to commit to memory

***

Incidentally the relationship of the Front and Rear Distances of Acceptable Focus is NOT always the 1/3 :: 2/3 relationship which is often mentioned as a “Rule”. Those who are mathematically interested can play with the formulae (or in line DoF Programs) and they will see that the factors: Subject Distance and Focal Length are of main relevance – however within my passion of wanting to make generalized practical application from my love of the Mathematics – it is safe as a generalization to assume that as we FRAME tighter the relationship of the Front and Rear Distances of Acceptable Focus becomes ½ and ½.

A useful example of this is when shooting a Group Portrait 1/3 :: 2/3 is a good guide, but for the range of Portraits from a Tight Head Shot to an Half Body Shot it is better to reckon ½ :: ½

> so for the Group Portrait of four rows of people – I’d generally reckon I would focus on Row 2 and thus the two rows behind and the one row in front of the row of people on which I focus, will be acceptable

> but for a Bust Shot of one person, I will reckon that equal distances in front of and behind the front eye on which I nail focus will be acceptable.

WW

[Dale2000]

All my SLR and DSLR cameras have this feature. However I have used it very seldom because of how dark the viewfinder appears when viewing stopped down.

Agreed! My Nikon has it, and it's only been used a couple of times in the last year and a half. With the image being shown on the rear screen after the shot has been taken, I don't find using it helps all that much, especially, as you say it's so dark.

[pschlute]

Agreed! My Nikon has it, and it's only been used a couple of times in the last year and a half. With the image being shown on the rear screen after the shot has been taken, I don't find using it helps all that much, especially, as you say it's so dark.

Are we talking about the same thing here ?

Some DSLR cameras have an option to use what is called "digital preview" as opposed to "optical preview".

Optical preview is the same preview that has been on SLR cameras since the film days: the DOF preview lever is pressed, and the aperture gets stopped down so one can see the DOF in the viewfinder. Depending on your chosen aperture the view can be very dark.

Digital preview is usually accomplished by using the same button/lever as above but instead of the aperture stopping down so one can look through the viewfinder, the camera actually takes a picture and displays it on the LCD screen as a preview. This preview should not be dark however as it is captured using normal exposure controls.

[xpatUSA]

Thanks Dem, out of town at relatives, so I'll have to dig later into my spreadsheets - one for magnification - one for distance. Both are based on an interesting paper by Richard F Lyon:

http://kronometric.org/phot/iq/DepthOfField-Lyon.pdf

Maybe there is a fundamental error in both spreadsheets because my numbers work both ways betwixt the two.

I'll get back to you later this week (today is Sunday here).

Well, I re-entered Lyon's formulae exactly as he wrote them in his paper and the numbers came out the same as before. I am at a loss to explain how he gains DOF for increasing distance at constant framing while all the on-line calculators stay about the same, as has been pointed out.

Probably best to drop the subject from this thread. I'll need to study his paper for quite a while . . . duh.

[xpatUSA]

Well, I re-entered Lyon's [DOF] formulae exactly as he wrote them in his paper and the numbers came out the same as before. I am at a loss to explain how he gains DOF for increasing distance at constant framing while all the on-line calculators stay about the same, as has been pointed out.

Probably best to drop the subject from this thread. I'll need to study his paper for quite a while . . . duh.

Done studying and it was indeed my error. I misunderstood the factor 'e' in Lyon's paper. Now the spreadsheets both work exactly as folks here say they should! Thanks, y'all . .

[pnodrog]

Done studying and it was indeed my error. I misunderstood a factor in Lyon's paper. Now the spreadsheets both work exactly as folks here say they should! Thanks, y'all . .

Always satisfying when the bugs etc are ironed out and everything works as intended.

[JBW]

This is interesting to me for several reasons. As a mirrorless shooter, I use the focus peaking color to tell me where the DoF is going to be in a given scene. Since I don't wear my reading glasses when shooting, I can't preview using the LCD or afterwards as in 'chimping'. The focus peaking will actually 'walk' the DoF forwards and backwards as I focus the lens, when using a manual focus lens, and thus I can see exactly what the camera considers to be 'in focus'. I've lately found that I get even better results using the focus magnification feature on my cameras that have it.

That's how I get my better shots. And it is a fast technique.

[Manfred M]

I first heard about chimping -and not to do it - in Lynda.com. It might not be right for some photographers but it is very useful for me.

Chimping is when you check out virtually every shot after it has been taken. Looking at the screen as you are setting up the shot to ensure that you are getting what you want is just good workflow. Doing so after changing camera settings or some other major way in your shoot, for instance camera position, lighting, etc. also makes sense. The screen on the back of your camera is far more than a replay feature. I often shoot with a histogram display to ensure my exposure is correct.

[Adzman808]

Mirrorless cameras typically perform all their metering etc with the lens set the widest aperture regardless of what aperture the user has set (as long as the camera is able to communicate with the lens of course)

So for example.

On my Fuji XF56 f1.2 lens

I set f8

The camera leaves the aperture on 1.2 to keep the evf bright and to aid focus acquisition and metering

Then when I 1/2 press the shutter, the lens stops down to the working aperture (in this case f8)

(Nb this is not so in continuous shooting)

If I engage DOF preview, this means I can see the dof without 1/2 pressing the shutter and also the shutter lag is an awful lot less

There’s a few posts here about dof

Nothing quite controls dof like subject distance! Dof on my 56 at f8 and min focus distance is inches, at f1.2 and infinity it could be miles (obviously f1.2 and infinity wont be the sharpest picture ever, but the focus will be there!)