Exposure settings



  • I realise that Superfly is supposed to provide physically correct lighting and fall off, but how can I simulate exposure time? My scene lights are casting too far, and with a camera flash I would resolve that with a faster shutter speed. Thoughts please?


  • Poser Ambassadors

    Gotta ask you confirm the basics. Did you set point lights to inverse square falloff?

    If not, start there.

    Also, you describe falloff ("casting too far") but ask for exposure control. These have nothing to do with each other.

    Exposure control is equivalent to simply increasing or decreasing all light sources (including glowing props) by the same ratio. I have done this with scripts.

    Note: Exposure is easily accomplished in postwork. Simply export your render in an HDR or EXR format, not JPG or PNG. Then you have literally the ability to control exposure in lots of other tools, in real time.



  • Poser neither knows nor cares what 'power' you think your lights are at. It simply generates light at whatever value you set the light (so another way to phrase BB's comment is that the light value you set IS your exposure control). Of course, that means all of your lights need to be set relative to each other in the scene first (again, as BB said, then ALL lights are adjusted the same to hit your target). The issue then is deciding how strong your lights need to be to properly illuminate the target object in your scene.
    0_1516745186233_apartment 1.jpg
    This scene has 12 spotlights pointing down at the floor. This render required one small area render to get a light reading, then I ran it through a calculator of mine and got a multiplier. All lights increased the same amount, rendered.
    How I did this is here: https://www.sharecg.com/v/90383/browse/3/Text-Entry-Tutorial/Lighting-Relationships-in-Poser-Second-Edition
    The calculators are here: https://www.sharecg.com/v/90382/browse/3/Text-Entry-Tutorial/Poser-lighting-calculator-spreadsheet
    I only published the second edition and calculators yesterday.



  • Thank you gentlemen. I think I misspoke. My understanding is that when you decrease shutter speed, the amount of light entering the scene decreases, and thus reaches less distance, so for instance, as in nature photography when a subject is photographed on a bright sunny day but by using a very fast shutter speed the back ground is black. I'm attaching an example of what I'm trying to accomplish, and I understand that this specific photo may have been done using post but there are some near identical ones that were simply photographed this way. And yes, I am using inverse square on my lighting.

    Thank you baggins for your suggestion about exporting in HDR. Does Poser always render in HDR regardless of your export format or do you need to have the HDRI optimised output selected BEFORE render?

    Thank your Piers for your tutorials. Regardless of whether they will address this particular issue, I look forwards to reading them. Your comments are noted, but I am only using a single point light. I want the head of a figure to be illuminated but not his feet.


  • Poser Ambassadors

    @matb said in Exposure settings:

    when you decrease shutter speed, the amount of light entering the scene decreases

    Hmmm. Since we have to use words to communicate regarding possible misunderstood concepts, I mean no insult but you're wrong there.

    Decreasing shutter speed in no way decreases the amount of light entering THE SCENE.


  • Poser Ambassadors

    @matb said in Exposure settings:

    and thus reaches less distance

    Also preposterous. The distance that light reaches is always infinite.

    Perhaps you mean to say, as I mentioned in my first response, falloff.


  • Poser Ambassadors

    @matb said in Exposure settings:

    when a subject is photographed on a bright sunny day but by using a very fast shutter speed the back ground is black

    I don't know what you're describing here. The background on a sunny day is bright as hell. (Generally speaking.) Your distance from it won't make it darker, and adjusting exposure only alters the brightness of ALL recordings in every direction and distance by equal ratios.



  • 0_1516803134805_lion-hd-wallpaper_015820727_22.jpg

    0_1516803451588_flash.jpg



  • Photons may have infinite travel, but they don't have the same effect at all distances. I already acknowledged that I WAS using inverse square fall off. The body builder image shows the concept I am trying to achieve - a very well lit foreground subject with parts not far away in near darkness. This is accomplished here with a flash and a fast shutter speed. What is the mechanism in Poser that you would use to accomplish this?


  • Poser Ambassadors

    @matb
    The lion image is clearly postworked and not at all the result of any lighting phenomenon.

    The bodybuilder is not flash from the camera. There is a spot light above and to the left - you can see the specular reflections from that light on everything and the shadow on the chair to the right.

    Your presumption that the background is lit by that light but somehow diminished is incorrect. The background equipment is actually in relative darkness.


  • Poser Ambassadors

    You should read the text that goes with the Marc Schultz image.

    http://marcschultz.com/blog/pros-cons-of-speedlight-photography/

    The whole article is about placing additional lights. Yes these are flash, but not pointed at the background.


  • Poser Ambassadors

    Marc wrote:

    "Despite all the pros and cons, all the photos you see in this post I shot very recently using only a group of three speedlights triggered remotely within a very dimly lit weightlifting gym in order to capture these images of a Thai bodybuilder."

    See? The background is dimly lit, not at all by the bright speedlight (flash) we see pointing at the person.


  • Poser Ambassadors

    0_1516812997896_Limited Range Light.png



  • Poser doesn't support the physical camera aspects of Cycles, much like it doesn't have an equivalent of Filmic to give a more realistic range of light and dark. If you want to work with exposure, I'd suggest downloading the latest Blender, the Real Camera add-on, and setting the Color Management (in the Properties: Scene panel) to View > Filmic. Blender's Cycles also has denoising, so you can us a lot fewer samples. Oh, and it has a Physical node to make setting up most non-procedural materials pretty easy.



  • To further BB's comments, if you want to emulate a flash, use a spot rather than a point light. It better represents the focused beam. Flash units are rarely isotropic.

    To Kobaltkween, Blender has filmic response as standard since 2.79. No need for the camera add on anymore.



  • @piersyf They're two different things. The physical camera add-on allows you set the scene's camera using real world camera settings, including f-stop and ISO/exposure. Sort of like you can do in DS/Iray.



  • I know, I have it. But your comment only mentioned filmic response, nothing about recreating a DSLR. Just addressing filmic response, default Blender has it. If you want extra emulation capabilities, get the add on.



  • @piersyf That is what it means to "work with exposure." It's only something relevant to cameras- how long the film or sensor is exposed to light. In other words, shutter speed, or ISO. And I was well aware of the inclusion in 2.79, which is why my instructions said how to turn it on, not how to download it.



  • I know the lion is post worked, I said that in my second post, and I'm not surprised that the bodybuilder image was lit with overhead lights - these were illustrative. I really appreciate you chipping in to educate me, but I am CERTAIN that I read in a digital photography magazine a few years ago, a technique for accomplishing the same LOOK using a combination of ultrafast shutter speeds and other settings. I don't know what those other setting were but low iso and wide aperture seem plausible candidates.

    I'm simply unsure how to accomplish this effect in Poser. You gents have pointed out how my vocabulary is wrong, and my understanding of the physics of light is wrong, but still nobody has offered a suggestion how TO achieve what I know is achievable.


  • Poser Ambassadors

    @matb said in Exposure settings:

    but still nobody has offered a suggestion how TO achieve what I know is achievable

    I really don't know what to do to move forward now. We've said in several different ways that you need to use spot lights to throw light on your subject but not on the background, and further that the rendered effect of dim vs. bright lighting can be enhanced through postwork with Poser. A suggestion was offered that you perhaps can get more what you want by NOT using Poser.


  • Poser Ambassadors

    @bagginsbill said in Exposure settings:

    0_1516812997896_Limited Range Light.png

    I also showed you this which shows a pointlight in a can prop, thus physically making the light NOT REACH the background objects.


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