Help me understand the camera!
Those Things
Posts: 1,132
I should start by saying that I'm a pro photographer, and during my career I've been privileged to work with a lot of camera and lighting systems, so I know what I'm doing. But the camera in Daz studio baffles me. The result I should expect to see with, say, a 120mm focal length, at an aperture setting of f8, is not what I'm seeing in my render. The depth of field is much more shallow, and I need to dial the aperture to what in the real world would be an unreasonable setting, to get near the results I'm expecting. And the focal distance seems completely off as well.
I'm sure there's got to be something I'm missing. Some little thing I'm failing to take into account. If someone could point it out to me, I can save a lot of time wasted fiddling!
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Some camera setting like F/Stop, ISO, Shutter Speed, etc. are controlled via the "Tone Mapping" in your "Render Settings" tab. This is where you can apply these "sunny 16" settings etc. .
This is valid for all cameras in you scene than.
The F/Stop in the Camera setting controls the depth of field.
In the "Display" settings of you camera you can set the "DOF Plane Visibility" to on. When "DOF" is on in the Camera Settings you can see the DOF planes and move them with the "F/Stop" setting of the camera.
While in perspective view and selecting the camera with the universal tool (Alt-Shift-U) you will also see the focus (Focal Distance) as a little ball and small boxes that control the DOF, frame width and focal length. So you can move these around with the mouse as well.
When selected with the standard nodes selection you can still the the focus of the camera as a little red/green/blue (x/y/z) cross and move it with the Focal Distance slider of your camera.
Kind regards, Eagle99
Thanks, Eagle99. So, if I'm understanding correctly, the "f-stop" in tone mapping is for the exposure aspect of the aperture setting, and the "f-stop" in the camera settings is for the depth of field aspect. And these two f-stop settings can be changed independently, without affecting each other's results. Will the camera's f-stop setting do both if I turn off Tone Mapping?
Nevermind, just checked, and turning off tone mapping just means you have to adjust the lighting recorded by the camera by physically adjusting the amount of light emitting from your light sources.
I'm not complaining, mind you. What I wouldn't give for a magical camera with two f-stops in the real world. :D
I'm no expert in photography, but what I expierenced so far is, yes these two work totally independent.
I stepped over this when trying to learn how to properly set up cameras in DAZ Studio.
This tutorial by sickleyield was very helpful:
https://sickleyield.deviantart.com/journal/Tutorial-Lighting-and-Tone-Mapping-In-Iray-531864617
Kind regards, Eagle99
And you are right about the camera settings f-stops and focusing scale not giving real world results. My usual f-stops for indoor use with a little bit of fore-and-background blur in Studio are in the f50-f150 range, rather than the f5.6-f11 that would give the same results in real life. I just ignore the numbers and use the sliders with the wireframe field and focus indicators.
Yes, that's exactly it. And I've learned that scale has a lot to do with it too. I always assumed that the daz figure was the cornerstone for scale in a scene, but now I'm learning that changing the scale of the items in the scene affects camera behavior as well (which makes complete sense). Oddly enough, you can also change the physical scale of the camera, and I suspect that this will have an effect as well. I've got some experimenting to do to confirm.
If only all this was in a manual somewhere...
I didn't experiment with changing the physical scale of the cam so far.
But here is at least an overview of the basic camera functions with some further links.
http://docs.daz3d.com/doku.php/public/software/dazstudio/4/userguide/chapters/cameras_and_views/start
The DAZ Studio Documentation Center isn't that bad...
Kind regards, Eagle99
For the most part, I've stumbled on the solutions/techniques mentioned here, so far. There is one aspect of the Camera Parameters I'm still baffled by (and have ignored to this point), which is the Lens parameters. Is that a section that real-world camera knowledge applies to, or is it unique to Iray. I intend to do some experimenting with different Lens settings, but I'd love some tips and pointers if anyone has some to share.
I fiddled with the camera settings myself some time ago .. What I found out is that setting the iso doesn't seem to work as expected, so it's better to use the shutter speed instead. Also I have to set the camera sensor to 64mm in blender to match the 36mm frame in daz studio. Sure there's something odd with the camera ..
Also iray doesn't support motion blur so if you're looking for photorealistic effects with moving objects you're out of luck.
https://www.daz3d.com/forums/discussion/206256/exposure-strange-behaviour
https://bitbucket.org/Diffeomorphic/import-daz/issues/99/camera-matching
Sensor size and frame size are two different things. The 36 mm size is the full frame size of a 35 mm film camera which digital cameras are based on. The sensor size, if that is what is used in blender, crops that depending on how much smaller it is than a full frame sensor which is equivalent to a 35 mm film camera.
http://photoseek.com/2013/compare-digital-camera-sensor-sizes-full-frame-35mm-aps-c-micro-four-thirds-1-inch-type/
Yes but the sensor should be smaller than the frame, not larger. In blender I have to use a 64mm sensor to match the 36mm frame in daz studio. That's why it's odd.
Frankly, I think cameras are pretty messed up in DS, nothing to do with the real world. DoF is seriously flawed. If you don't do adjustments to it using ridiculous values, everything looks like you're using some kind of macro objective shooting small scale models:( Rant over:) Hmm...should really contact DAZ about this
The "physical" size of the camera object won't matter. I've done some strange things like making really small cameras parented to eyes to make it easier to aim the character's view at what they should be looking at. It doesn't affect the render at all. From a rendering engine standpoint, your camera is an infinitely small point anyway. All the scaling does is change the size of the outline in the scene.
What you're seeing from a scaling of the items is that certain calculations are based on what's called the "bounding box" of an item. This is basically an invisible box that conforms to the very edges of an object. For example, a beachball (sphere) would still have a cube for it's bounding box. The bounding box may be used to decide if the object is going to be affected by a certain process (e.g. depth of field calculations). The actual effect is calculated at the specific points on the surface, but the bounding box could adjust which objects are considered by certain parts of the code during rendering.
This is done to accelarate the rendering process. For instance, if I have a mirror reflecting other objects, if the bounding box is completely outside the view of the mirror, I don't have to process that object at all. However, in some cases (like when you're trying to achieve very precise depth of field effects), you could run into some fringe cases where resizing the object (changning the bounding box) has an effect on your final outcome.
Hi, Avmorgan. Despite all my experience with Daz, I still have yet to fully understand the camera. But I can say this about the lens parameters; they will behave as you would expect them to in the real world, in terms of focal length, with a few caveats. So, if you use an 8mm lens, you will get a lot of distortion (like you would expect), but it isn't proper barrel distortion. It's something else entirely, a mere simulacrum. To achieve the "fisheye" distortion you'd expect at 8mm, would require some sort of in-scene prop. In fact, the store contains a prop like this for sale: https://www.daz3d.com/small-world-camera
But if you're not talking about extremely short focal lengths, you'll get fairly reliable results. Longer focal lengths will compress perspective, and shorter focal lengths will exaggerate it. And, there is even a switch to turn off perspective entirely, regardless of focal length. How great would it be to have that in the real world?
Because of a bug, Daz Studio at least when rendering in a landscape format it's extending the picture to the left and right instead of cropping top and bottom. Therefor the perspective is completely wrong. I noticed that the only perspective that's coming out right when using the 36mm (Full format DSLR sensor width) is 1:1.
As a little workaround you can change the frame width to the theoretical frame height (24mm for 3:2 format, or 20.25mm for 16:9 and so on) by shortening the width and Daz Studio extending it due to the bug, you end up with a correct render that now fits to every other render from Software like Blender, Cinema 4d, 3ds Max, Maya, Unreal Engine, Unity and of course to RL-Photos.
P.S.: Girls usually like shorter focal lengths because it makes their neck and waist thinner and things closer to the cam bigger. Boys on the other hand prefer their neck to appear thicker -> larger focal length. ;)
Thank you so much for this tip! I assumed I was doing it wrong in my DCC of choice (Houdini), but you're completely right, Daz's frame width value is off by the aspect ratio of the render. Much appreciated :D
– Dave
Well, that explains some of my experimental results. Good to know. I think I even have the Small World Camera. I'll have to double check that. Thank you.