Cameras should display DOF in viewfinder IMHO

[Scott Stephen]

Wouldn't it be helpful, and also educational, if the camera were to display the DOF in the viewfinder when you lock focus? The camera knows the focal length, and the aperture, and the distance at which it has locked focus, so it should be able to pull that trick off for you using a simple calculation.

I still forget the huge difference it makes to DOF when you zoom in. I know i have had hundreds of OOF shots over the years due to forgetting this factor. I think a lot of folks would pick that up more quickly if the camera was constantly reminding them.

I know the camera has a depth of field preview button, but 1.). It is dark and hard to see the image if stopped down, and 2.) this is (for me) easy to forget as mentioned above.

Is it just me?

[Mike Buckley]

The camera knows...the distance at which it has locked focus

Is that really true? I'm asking because I've never seen or heard anything about that.

[PhotomanJohn]

Mike - The statement is true. In the case of Nikon, this began with their "D" (for distance) series lenses in the 90's.

John

[Mike Buckley]

In the case of Nikon, this began with their "D" (for distance) series lenses in the 90's.

Ahhhhhhhhhh, yes. I had completely forgotten about that.

[kris]

IMHO I do not think that seeing the DOF expressed as length in the viewfinder is really useful, as it is not so useful to see the distance at which the camera has locked focus expressed as length. This is only useful for in studio photography, where you can measure distances.

I make a large use of the DOF preview button of my camera, and I find it generally useful. For large f numbers the preview can be quite dark, that's true. When I cannot judge the DOF with the preview button, I just bracket varying the f/number. Playing with DOF means you have time to compose the shots, so bracketing it is generally not a problem.

Cheers
A.

[Mark Treen]

It is very unfortunate. I think it brings up some neat concepts that may be cool to read about to some.

We are up against plain old physics here. You will never get a DSLR that shows actual DOF in the view finder and not be dark when stepped down. The Aperture is getting smaller then your pupil and you're retina can't take a 1/2 second shot. It's also dark because roughly 2/3's of light is lost (depending on the color of the subject). Some being right at the sensor when collecting it in RGB "buckets" (photoreceptors).

A few other issues exist. The wide open aperture in your lens before shooting the picture is used by the AF system to get focus. If the lens was stuck at f/8 it would have a tremendously harder time to get focus, all other things held constant.

The other is that the DOF preview button is not super accurate. This is because photons converging on the image plane (focuses picture) have a different path to get t the view finder. It's a different plane that tries to simulate the Image Plane.

Another reason is the concept behind how we define focus, Circle of Confusion.


Most non-SLR cameras have this licked because they don't depend on viewing the actual photons from the lens.

[William W]

Wouldn't it be helpful, and also educational, if the camera were to display the DOF in the viewfinder when you lock focus?

I assume you mean a display of two figures representing distance?

Very Good Idea. Patent it and make some money
Should be relatively easy to implement – but not all lenses will be recognized apropos Focal length, but that’s really no big deal.

It would be one of those functions that I personally would use rarely, but when I did use it, it would be valuable.
I’ve learnt the DoF for the key Framings for Portraiture (i.e. Full Length; ½ Shot; Head shot) for the three key Apertures (F/2.8; F/5.6 and F/11) at both Orientations – and they’re quite easy to remember - and enough information for 99.99% of my shooting – but where I would use such an application is for Groups Shots.
It would be easy to have User selection for the CoC (Circle of Confusion)

Very good idea, well done. - much more useful than "wifi"

WW

[William W]

We are up against plain old physics here. You will never get a DSLR that shows actual DOF in the view finder and not be dark when stepped down.

I assumed the OP meant a numerical display in the LED viewfinder - that was implied by the Header Title of the thread.

WW

[Stagecoach]

Scott,

If we consider that lens manufacturers used to make this information, although perhaps rather crudely, available on the lens as assistance to the photographer it's surprising that this has not been adopted as available 'data' within the modern DSLR.

As Bill said it would not be a requirement for many most of the time, but, there are also numerous options on my camera that I rarely use but when I do need them they are valuable.

[pnodrog]

Just be aware that to prevent hunting the autofocus system only looks for an acceptable focus and the focal distance indicated by the lens may not be exactly the same as the distance to the object being focused on. The faster and longer the lens due to it's shallower DOF the smaller the discrepancy will be. If you are auto-focusing using a slow very wide-angle lens the difference between exact focus and an acceptable focus may be significant. A camera could only give the DOF based on the distance indicated by the lens which may not be the DOF achieved by very accurately manually focusing on the object(subject). Camera manufactures are probably very cautious about displaying a DOF value as it could on occasions be misleading.


I have not checked to see if any of the live view or electronic view finders offer a “bright” DOF preview but it should be possible. With practice it is surprising how good you can get at peering at a SLR viewfinder with the DOF preview button pressed but under low lighting levels it can be a waste of time.

[MarshallG]

How would the viewfinder indicate DoF? Just the number of in-focus feet/inches of focus from the focus point?

For me, that would be just one more bit of viewfinder clutter, but I can see how some might find it useful. I find my viewfinder overwhelming as it is, although the info is necessary. DoF calculation is something I can do without.

[pnodrog]

How would the viewfinder indicate DoF? Just the number of in-focus feet/inches of focus from the focus point?

For me, that would be just one more bit of viewfinder clutter, but I can see how some might find it useful. I find my viewfinder overwhelming as it is, although the info is necessary. DoF calculation is something I can do without.

Sorry I was meaning that the actual DOF could be observed within the scene as viewed in the view finder not a displayed value.

[William W]

I have not checked to see if any of the live view or electronic view finders offer a “bright” DOF preview but it should be possible. With practice it is surprising how good you can get at peering at a SLR viewfinder with the DOF preview button pressed but under low lighting levels it can be a waste of time.

I am quite confident that all Canon DSLR’s with Live View allow the DoF to be seen in it.
I expect, though I have not checked, Nikon would be the same.

Taking the functionality of my 5DMkII as the example:

As already mentioned, when one presses the DOF Preview the Optical Viewfinder becomes darker often, making it difficult to assess DOF.

However, Live View automatically adjusts the display brightness when the DOF Preview Button is depressed. Also, one can use the x5 or x10 on a particular section of the scene, to check focus of that area, with greater accuracy.

WW

[NorthernFocus]

Great idea. Heck even if it simply displayed focus distance I'd be happy.

[Tringa]

Viewfinders tend to be a bit full, but I think camera makers could find a way of making a useful DoF display as you suggested Scott.

Perhaps instead of the viewfinder going dark as the lens stops down when the DoF preview button is pressed the viewfinder could display three numbers. The centre one would be the distance to the the object in focus, the other two show the distance of acceptable focus in front of and behind the subject. So you would see, for example, 4.6, 5.0, 5.5 indicating the object in focus is 5 feet away and the DoF is from 4.6 feet to 5.5.

Dave

[Stagecoach]

With software in cameras today there is no end to options that could be given as a means of indicating DOF as long as the 'distance' is fed back from the focused position. It would also be able to cater for zoom lenses as the lens focal length is also fed back to the camera.

Indication of the figures in the viewfinder is not the only option and the LCD could be used for this in the same way that on my camera I can select to view camera settings on it. It would be quite easy to have three vertical bars, the centre being distance, with figures above them as Dave mentions.

[Andrew1]

The DOF markers on my older lenses were at best, an estimate however I used them all the time and they are a great help when I shoot film. Stopping down gives a much closer idea of what the resultant photograph would look like and I use that very effectively as well.

A problem I see of building it in to a digital camera as a standard is who is to say at what level of distortion, which some reference as the circle of confusion, is to be established as the standard? Is it to be a measurement within the camera or is it simply a calculation? If it's a measurement within the camera, the software to distinguish edges would need many more focus points to analyze the sensor data and try to determine if the lack of detail is caused by distance or is it just a petal on a rose? At best, I think it would resemble an unsharp mask filter which again, is subject to personal control.

If it's simply a table then accuracy would be suspect with each lens. Standard lenses aren't all exactly the same and can be subject to small variations. Acuity within the range of a single zoom would be even worse to build tables for.

In either case, measured or calculated, I can only see problems for the camera manufacturer. There are a number of factors that contribute to the level of visual acuity of a photograph. How big are you going to blow it up? Is it on screen or a print? What camera model did you use? What lens did you use? What light are you viewing it in? How far away from the print are you? etc.

Sometimes we can be a picky bunch and this I think is not worth the headaches it would cause the builders.

[Stagecoach]

Andrew,

You make valid points but as an 'aid' to the photographer it could offer exactly the same info as what we get when inputting the same figures into a DOF calculator or chart. Calculator input = aperture, lens focal length, distance. Output = DOF with near and far figures.

An electronic version of the markings we used to have on the lens barrel.

[William W]

The DOF markers on my older lenses were at best, an estimate. . .
In either case, measured or calculated, I can only see problems for the camera manufacturer. There are a number of factors that contribute to the level of visual acuity of a photograph. . . etc.

I don’t see these matters as problems.

***

An electronic version of the markings we used to have on the lens barrel.

Absolutely.
An electronic function would also be an indication only.
And at times, for some, a very useful indication.

A visual (numerals indicating distance) would be more accurate, than establishing where on the Focus turret to align the Distance Numeral with the engraving of the F/number on the lens barrel.

As mentioned previously the CoC could be User Selected. Photographers who would opt to use that feature, could select the CoC to reasonably account for Enlargement, etcetera; as well as their own Subjective Limits for DoF.

WW

[Andrew1]

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

An earlier on-camera version.