Camera Headlamp vs. No Head Lamp
Maybe it's my untrained eye but I don't really see a difference for rendering in Perspective View vs. A Camera but I do use a camera sometimes when I think of it. Last night I was doing a render and realized I hadn't turned the headlamp off. So just for fun, I did an on and off render and didn't really see a difference. I hear you should always use a camera with the lamp off and not Perspective view but can someone explain why in laymans terms?
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The headlamp is a light that sits right on top of the camera. By default, it will switch off when you have any other light that isn't HDR or mesh, in the scene.
It has the same effect any light has. Too much light will bleach out colours and sometimes create other unwanted effects.
You can test it easily by switching to "Scene only" in the render settings. Try your test render again, with no other light in the scene, and you'll see just how strong the headlamp is.
To add a comment about two other issues you raised:
1. The views (Perspective, etc.) aren't cameras, and while each has a headlamp, it's not controllable. These views also lack some of the other features found in an actual D|S camera, which is why you want to create a new camera and use it for rendering, rather than render from any of the views.
2. The advice sometimes given about *never* using a headlamp is bunk. Use it when it lights the scene the way you want. The headlamp provides a kind of hard fill that's useful in certain situations. The quality (tonal appearance) of the headlamp depends on the renderer you are using. In Iray, the headlamp more closely resembles the light quality of a directional point light.
Be aware that you can change the offset and intensity of the headlamp using the related controls in the camera panel. Like a fill light attached to a real camera, you can use this feature to alter the axis of the light related to the lens.
Tobor gave some good advice regarding the headlamp.
The "headlamp off" advice stems from the fact that many a user has set up a mesh & light-hdri setting and suddenly finds the scene flooded with light.
Here are some render examples with and without headlamp for the camera:
Headlight on:
No Headlamp, HDRI only:
As you can see, the default headlight washes out the shadows. As Tobor pointed out, you can use the headlamp as a fill light, but the default usually ruins the setting when you are using pre-made sets.
In the closeup, you can see the difference even better, and the skin loses a lot of details due to too much light.
No headlamp:
All good info! Thanks everyone. One more question...
As someone that enjoys doing picture series and frets render times...is it the more light you have, the easier for Iray to render or the more light you have makes it harder? Or did I make all that up and it's not even a thing? I pretty much use an Iray interior light right that I bought maybe a few spot and point lights to eliminate shadows when need be and then a distant light to make sunlight through the windows. I have tried HDRI before but am pretty confused by it and didn't want to go over board on lighting and blow my render times into the ionoshpere.
Sort of, and it depends. The speed and efficiency a render cleans up at can be affected by many things, including exactly what's in your scene, the lighting, and what kind of materials you use.
Note that Iray renders never actually complete, they hit stop conditions — render time, number of render iterations, and "convergence", which is a sort of measure of completeness. These have default values (7200 seconds or 2 hours, 5000 iterations, and 95% convergence) and can be adjusted in the Render Settings tab, Progressive Rendering section. A couple of things to watch out for; most of the adjustments that improve your render will increase render time, and the Convergence value should never be set at 100%, although you can get very very very close to 100%.
I think of the headlamp as a flashbulb attachment on top of the camera. It produces a similar effect, and, as with a camera, sometimes that's just what you want.
Another reason to create a camera when you first start a scene and use that is because the placement of the Perspective camera does not get saved with the document. You can put the Perspective where you want, but if you save and close, the Perspective camera will be back at its default when you reopen.
Laurie
Sorry, dumb question, but is the perspective camera the one called default camera in the scene tab?
No, Perspective Camera is a view of the scene but the position isn't saved with the scene. The Default Camera is a fixed camera and is saved with the scene and opens with the last view it was showing when the scene was made.
Thanks Fishtales
It's called Perspective View in the list of cameras/views.
I was going to mention this as well. Until I figured this one out, the most frustrating aspect of Daz Studio when I first started was the scene not retaining the "camera" position when I saved.
Another difference is if you are viewing the scene from a camera and move the camera, you can use Undo to step back to the original position. Because Perspective View, isn't a real camera, if you move it and then want to move back, Undo won't help you. You can also lock a camera into position so you can't accidentally move it. (It's not a one button operation. Just ask, if you want a step-by-step how-to.)
I like to use Perspective View to frame the scene initially, and then create a Camera, using the options to apply the same view to the Camera. Then I can continue to zoom in and out, rotate and so, to work on the details of the scene.
You can also have multiple cameras. One trick I use ocassionally is to create a camera that frames a close up of the character's face. Then I parent that camera to the character's head, so regardless of the pose, the camera is still showing me the face. This can be really helpful with posing an interaction with something else, whether the face of another character, or a hard object like a stone, (or a fist!)
If you have a completed scene with a camera used for the final render, you can create another camera to do a closeup render of another area of the scene without losing the camera angle/position of the main render.
In fact, It's not unusual for me to have several cameras saved with a scene, even if I only ever use the primary camera for renders.
I rely on the headlamp a lot, for posing, and sometimes for rendering. It's very frustrating when the cameras are all dark simply because there's one actual light in the scene. IMHO, the Perspective Camera headlamp should never turn off, or else they should give the option like other cameras. Since the headlamp can't be controlled on the Perspective cam, would be nice to have an option for "normal" cams to not be part of the undo set.
What I typically do is setup three cameras with a new scene:
1. Posing cam. Headlamp on so I can see what I'm looking at regardless of the lights in the scene. I setup the render view with this camera and render with one of the cameras below.
2. Render cam. Parented to the Posing cam. I lock all the rotate and trans parameters, so you can't accidentally move it. Headlamp is usually off, or set to low intensity.
3. DOF cam. Also parented to the Posing cam and locked. Also with headlmp off or low intensity.
While I was typing this, I finally setup a preset with the above three cams so I can easily add them to a new scene. Should have done it a long time ago, but just never got around to it.
One thing to keep in mind is that the headlamp can create an artifact in your rendered scene. It will show up as a rectangle, either bright (especially on glossy surfaces), or as a shadow under certain conditions. This drove me nuts for some time until I finally figured out what it was.
"the Convergence value should never be set at 100%"
I don't agree. I always set mine to 100 percent. I rarely ever get there, but I'd rather it be at 100% in case a render gets to 95 and stops and isn't as good as I want.
I almost always cancel a render in the high 80s to 90s anyway, then save it. But it doesn't hurt anything, doesn't slow your render time, to have it at 100%.