The Long Wait

[Tangled-Universe]

Exactly Richard!
On top of that, with true depth of field you can subtly see blurred versions of background elements which would otherwise be obscured by foreground elements. In fields with grasses/flowers etc this is most prominent.
Using depth maps is broadly accepted though and when used with care or with its limitations in mind -like you just explained- it can give good results. In this render I could not tell immediately the dof was not natively rendered.

@WAS Your photo looks hyperfocal to me pretty much from foreground to background, except for the little veggy on the very left- and right-foreground. Could also be movement, if you say this was shot on a windy day.
It's also just not tack sharp anyway all across the image which may give the impression that the background is slightly softer.

The default dof settings in TG are...well...they make no real sense from a photographers perspective.
The default fov is set to 60 degrees, which is a kind of but not widely accepted equivalent of human sight's fov.
The resulting focal lengt of 31 something mm does not exist as a prime lens. A zoom lens could do it, but it's definitely not a standard focal length.
The focus distance of 100m is just a value I think. I see no intent there and frankly neither with the aperture size of 5 mm.The resulting f-stop of 6.2 is a bit funny. "Classical" f-stops would be something like f/2 f/2.8 f/4 f/5.6 f/8 f/11 for obvious reasons.All in all TG's default camera settings are merely placeholders I think.Getting back to your photo...the file does not contain EXIF data unfortunately, so I can only make some educated guesses.The fov looks pretty standard to me, so I guess this is something like a 35mm lens, definitely not wider and if it's more tele then it perhaps could be 50 or 55mm.Perspective is not flattened, so definitely no focal length >55mm I would say.Lenses ranging 35-55mm with small apertures like f/8 have hyperfocal distances of 5-10 meters.That fits perfectly with my observation.Say aperture is f/2.8 then hyperfocal distance would be 15-30 meters, which would also result in a hyperfocal horizon for sure.The smaller the aperture the more nearby the hyperfocal distance is.
(actually and factually, if you focus AT the hyperfocal distance then everything is in focus at half that distance already)

TG's default camera has it's hyperfocal distance at around ~5 meters as well. The online charts have no 31mm @ f/6.2 (what I meant before), so I had to guess a bit.
So with default settings you will have some slightly blurred foreground elements, given they are close enough and the rest will be in focus.
That's all the intent I can distill from TG's default camera.

[WAS]

Exactly Richard!
On top of that, with true depth of field you can subtly see blurred versions of background elements which would otherwise be obscured by foreground elements. In fields with grasses/flowers etc this is most prominent.
Using depth maps is broadly accepted though and when used with care or with its limitations in mind -like you just explained- it can give good results. In this render I could not tell immediately the dof was not natively rendered.

@WAS Your photo looks hyperfocal to me pretty much from foreground to background, except for the little veggy on the very left- and right-foreground. Could also be movement, if you say this was shot on a windy day.
It's also just not tack sharp anyway all across the image which may give the impression that the background is slightly softer.

The default dof settings in TG are...well...they make no real sense from a photographers perspective.
The default fov is set to 60 degrees, which is a kind of but not widely accepted equivalent of human sight's fov.
The resulting focal lengt of 31 something mm does not exist as a prime lens. A zoom lens could do it, but it's definitely not a standard focal length.
The focus distance of 100m is just a value I think. I see no intent there and frankly neither with the aperture size of 5 mm.The resulting f-stop of 6.2 is a bit funny. "Classical" f-stops would be something like f/2 f/2.8 f/4 f/5.6 f/8 f/11 for obvious reasons.All in all TG's default camera settings are merely placeholders I think.Getting back to your photo...the file does not contain EXIF data unfortunately, so I can only make some educated guesses.The fov looks pretty standard to me, so I guess this is something like a 35mm lens, definitely not wider and if it's more tele then it perhaps could be 50 or 55mm.Perspective is not flattened, so definitely no focal length >55mm I would say.Lenses ranging 35-55mm with small apertures like f/8 have hyperfocal distances of 5-10 meters.That fits perfectly with my observation.Say aperture is f/2.8 then hyperfocal distance would be 15-30 meters, which would also result in a hyperfocal horizon for sure.The smaller the aperture the more nearby the hyperfocal distance is.
(actually and factually, if you focus AT the hyperfocal distance then everything is in focus at half that distance already)

TG's default camera has it's hyperfocal distance at around ~5 meters as well. The online charts have no 31mm @ f/6.2 (what I meant before), so I had to guess a bit.
So with default settings you will have some slightly blurred foreground elements, given they are close enough and the rest will be in focus.
That's all the intent I can distill from TG's default camera.

 I don't think the actual camera specifics were mentioned besides a small aperture and foreground and background in focus. The common look for those dreamy vistas where only really the horizon or very-very distant structures in haze seem to lack focus.

I assumed it's wind because the blurry only happens on what would move in wind. Weeping willow, bushes, gras. Everything that would be still despite wind is in focus. Common in over-exposure for dreamy light.

Additionally, photography is heavily digital now, where FOV, focal length, aperture, etc, are all on sliders and customizable within fractal ranges. Although on some devices this may be just simulated like on my LG G8. Can't imagine all those settings are "realistic". Sure don't look like it.

[KyL]

Interesting talk about DoF, and you guys pretty much explained why I choose to go the 2D-based approach.
I like how you can set up the dof in Terragen and adjust the f-stop number, it gives an interesting photographic approach to it. The thing is that indeed we do not really know how accurate this compares to a real camera.

Ideally one would need lens profile with correct lens deformation, defocus and aberrations, and this would be rendered by the renderer through a lens shader. This would be quite overkill and I don't even know where you could get this data from. (probably the lens manufacturer?).

But this takes away a lot of the flexibility and artistic decision from the compositing step.
There are some really awesome lens plugin for nuke and it is still, to my knowledge, the favorite way to do the dof in VFX.
Back to Terragen, this (and mostly the artifacts) made me use it only as a reference. There is also much more control in comp such as the shape of the blur, the number of blades of the aperture and so on...

I also bought his most recent model, the orange one, looks really great and I have some ideas for it. Also needs rigging *shrugs and sighs* haha

Nice! My thought exactly on rigging... So this is why you should try mixamo. I was surprised to see how good their auto rig worked. It's far from perfect but this gives you access to many poses and animation! I'll drop you a MP regarding the rest

Dropping this down to a far clip that is just touching the horizon (maybe 10000) or even closer gives the grey scale depth pass much more detail.

Interesting. Does this gives any benefit over rendering the default clipping at 32bit?

[Matt]

I often find that Terragens default set up for outputting a Depth render layer is not that good.

This is down to it's far clipping distance being at 1e+016.
...
Dropping this down to a far clip that is just touching the horizon (maybe 10000) or even closer gives the grey scale depth pass much more detail.

Do you mean the clipping distance in the Render Layer? This shouldn't change the output of the depth elements. Does it? As far as I'm aware, the depth element values are 1/z, measure in metres. Something 1 metre away from the camera has a value of 1. Something 10 metres away has a value of 0.1, etc. If you take this into Nuke (for example), you might be using a node that remaps these values to something else, but the output from Terragen uses a fixed mapping so that there aren't any unknown variables.

[Matt]

Terragen's built-in DOF has two options: One is purely ray traced and doesn't use the depth buffer at all, and the second option "DOF with noise reduction" is a hybrid approach that uses both ray tracing and post process using depth information in the subpixel depth buffer (which has more information than the output depth element). There is a bug in this, and artefacts can occur at points close to the focus distance.

[cyphyr]

I often find that Terragens default set up for outputting a Depth render layer is not that good.

This is down to it's far clipping distance being at 1e+016.
...
Dropping this down to a far clip that is just touching the horizon (maybe 10000) or even closer gives the grey scale depth pass much more detail.

Do you mean the clipping distance in the Render Layer? This shouldn't change the output of the depth elements. Does it? As far as I'm aware, the depth element values are 1/z, measure in metres. Something 1 metre away from the camera has a value of 1. Something 10 metres away has a value of 0.1, etc. If you take this into Nuke (for example), you might be using a node that remaps these values to something else, but the output from Terragen uses a fixed mapping so that there aren't any unknown variables.

Yes you're right.
I did a quick check to confirm.
I think I must have been using 16bit depth passes in the past but definitely 32 bit passes show no difference by changing the clipping distance.

[Matt]

Good to know that's working. Thanks for checking, Richard.

[Matt]

The default dof settings in TG are...well...they make no real sense from a photographers perspective.
The default fov is set to 60 degrees, which is a kind of but not widely accepted equivalent of human sight's fov.
The resulting focal lengt of 31 something mm does not exist as a prime lens. A zoom lens could do it, but it's definitely not a standard focal length.

We could change the default camera to use a more common focal length. What would you like the default to be? I think 28 mm might be a good choice. It's quite close to the current default. I feel that 35 mm is a bit too zoomed in for the default for a landscape application. What do you think?

The current default of 31.18 is calculated automatically from the default FOV of 60 degrees (horizontal), as that was always the default FOV before focal length controls were added. That choice of FOV is arbitrary, and you can change the focal length to any thing you like and it will change the FOV accordingly; it should all be calculated correctly. If you set the focal length to something "standard" like 28 mm or 50 mm you should get a good simulation of a full frame camera using a lens of that focal length. The default sensor size is 36 x 24 which I believe is standard for a full frame camera (but also editable if you want).

The focus distance of 100m is just a value I think. I see no intent there and frankly neither with the aperture size of 5 mm.The resulting f-stop of 6.2 is a bit funny. "Classical" f-stops would be something like f/2 f/2.8 f/4 f/5.6 f/8 f/11 for obvious reasons.

True, the resulting f-stop with the default aperture size is not something you'd normally see on a camera because it doesn't sit exactly in one of the usual slots. The text will show you whatever the equivalent f-stop would be for the chosen aperture and the current focal length, even if the combination isn't possible in a real camera. But you can adjust the aperture to make it fall into one of the limited slots available on a real camera.

Interestingly, if the default focal length were 28 mm then a 5 mm aperture diameter would result in f/5.6. So that's quite nice. But, again, the 5 mm is arbitrary and can be changed to almost anything you want to closely match a real camera.

[Tangled-Universe]

Sorry Matt, I did not mean to make you defend those choices.
Whoever wants to do something kind of realistic with it should know a bit of basic photography principles and it's nice that you explain the relation between some settings for those not very familiar with photography.
I meant to say that whoever is not very well versed with photography principles that the default TG camera is by no means a 'photographic one' and that most values are perhaps better to be considered placeholders.

Therefore I don't think the default is bad, it never bothered me and I can make a default scene myself.

But, if I'm asked to choose, well then 24 or 28mm would be my default. Depth of field is usually pretty big with these focal lengths, so to make it noticeable when someones enables depth of field in the renderer then default focus distance should only be a couple of meters and aperture around f/1.4 to f/2.8. Sigma ART

If you feel like it, could you tell us a bit about whether if TG would benefit from physical camera shaders, like in VRay? Those also have shutter speed and ISO, but conceptually these seem to me just like a few extra buttons/sliders to give people the idea they are handling a real camera.
Perhaps increasing ISO would add a nice grain, but else shutter speed/aperture/ISO are part of the exposure triangle and TG is easier by just offering 'exposure'.
Are we missing out or are there true benefits to physical cameras like in VRay/other renderers?
Would they be combined with a nice photographic film response? Your tonemapping is already nice, so I'm just curious what could be improved in TG when it comes to the camera node. Sorry if this is a bit messy, just oozing out my thoughts here.

[KyL]

Interestingly, if the default focal length were 28 mm then a 5 mm aperture diameter would result in f/5.6

I'm 100% done for this default settings. Usually I always change to 28mm anyway and 5.6 is a nice start for a good dof.