Christmas set up with lights and help with AF

Discussion in 'Beyond the Basics' started by CherylL, Dec 5, 2017 at 3:33 PM.

  1. Derrel

    Derrel Mr. Rain Cloud

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    I would immediately hang the background so it is "wide", not "tall". The issue with a narrow background is that it can be difficult to get the background to fill the width of a horizontal camera shot. Making the lighted background W_I_D_E_R will immediately give you a much easier set to work with, and will allow you to use different lens focal lengths with much more ease and fluidity.

    The lens focal length determines the angle of view behind the subject; a 24mm lens could fill the frame with the dog and sled, but the entire back wall would show! A 50mm to 100mm lens.

    ADDING more light by upping the flash power is the wrong approach, I think.

    Shutter speed and ISO are the easiest ways to regulate how bright the LED lights will be shown; the FLASH is regulated by the ISO used, and the f/stop, but the shutter speed has zero effect on the flash exposure. You can make the background lights as dim or as bright as you want, by changing the shutter's "open time duration"; adding more flash can actually be counterproductive.

    If you ADD flash lighting on the subject, it will tend to make the background LED's register as dimmer...

    Shutter speeds of from 1/40 to 1/8 second could be useful, for getting the LED lights to register at different brightness levels, when using say one speedlight, ISO 200, and f/8-ish. Thse LED's do NOT look all that bright to me, based on your f/2.8 exposure setting.

    Lens aperture size, in both f/stop (focal ratio number) AND the actual, physical width of the hole in the lens (which determines background blur, and also, depth of field. Ergo...with a small lens, like a 50mm lens at f/2.8 you get smallish bokeh balls; with a 200mm lens at f/2.8 (same focal ratio), the p_h_y_s_i_c_a_l_l_y w_i_d_e_r hole in the lens will create LARGER bokeh balls.

    So...if you want larger out of focus bokeh balls on the background LED's, you will want to use a larger f/stop with a physically longer lens.

    Moving the tripod as far back as you can, and using the absolute longest focal length lens you have (135mm,180mm,200mm,300mm) will make the background blur circles (the bokeh balls) BIGGER. This is physics...depth of field is discussed a lot, but not so the topic of background blur.

    The issue with longer focal lengths is that you can get the dog to be say 1/3 the width of the entire frame, but the longer the focal length used, the narrower the angle of view _behind_ the subject. So...it's always a balancing act....camera-to-subject distance, and focal length used, and the amount of physical background width shown in the picture. Wide-angles will show lots of backdrop width; extreme telephotos will show a narrow slice of the backdrop.
    **********

    Looking at the basic exposure info you gave: ISO 200, f2.8 and the speedlight at 1/8 power. Whatever the shutter speed you used, it looks GOOD. There's absolutely nothing wrong with the speedlight at 1/8 power for f/2.8 and ISO 200 and your shutter speed: you have a VERY nice balance of the exposure triangle!!!

    But, you could get bigger bokeh balls with a longer lens, at f/2.8 or even f/4 or f/5.6, from much,much farther back than with the 50mm lens.


     
    Last edited: Dec 5, 2017 at 10:49 PM
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  2. smoke665

    smoke665 TPF Supporters Supporting Member

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    @Derrel I agree with most everything you say with some slight differences. In the OP's first post the DOF is so shallow that when you look it enlarged the point of focus appears to be at or just past the nose, the eyes are not sharp and the ears are going OOF. Given the length of the dogs nose, I'm guessing she was less than 7-8 feet from the subject. In looking at her setup, and the room, it appears she may not have much room to backup, putting a longer focal length out of the equation for anything other than a head shot.

    As of late I've logged a few toddlers, and the first thing that comes to mind is they don't stand still, and the second thing is they move around (alot). While her exposure may be correct, it's not necessarily the right one for the subjects. By raising the aperture up to f/8 you increase the DOF sufficiently that you don't have to worry about a slight miss on focal point. I've been taught (and use from experience) that the key should be slightly above eye level. In the OP's post her setup has the key way up high, then she reduced the power level. I've had better success with adjusting the light to cover a zone (allowing some movement), adjusting the power to give me the aperture required, and moving the lights in closer or increasing the size of the light to give a softer light that will wrap around (again within the zone). What shutter speed or ISO to me is a matter of preference, I'm just more comfortable with ISO 100 and 1/100 or 1/125.

    I agree with you on the bokeh, except that given the subjects, I would eliminate a needless problem, by coming back and shooting the background sans subject and props, to get the look I wanted, then add back to the image post.
     
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  3. Derrel

    Derrel Mr. Rain Cloud

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    I would shoot is all in-camera, and not add anything in post.

    ISO and shutter speed when combining an actual ambient light source is more than preference; it's a matter of requirements, because the flash-to-ambient ratio is set, and the flash is one exposure, the ambient is another.

    The height of the key is not too critical on the dog, since the floor's white rug gives huge fill bounce. But it does determine catchlights.

    Wish I had more time, gotta run.
     
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  4. Designer

    Designer Been spending a lot of time on here!

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    We did the nom. for POTM, December, 2017
     
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  5. Designer

    Designer Been spending a lot of time on here!

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    To be filed under "mostly useless information" is this little tidbit: LED lights actually are pulsing at about 60Hz. Our perception is that they seem to be a steady glow, but when you hit the shutter opening just right, they will appear to be off. This is why you need a longer shutter speed to see the LED lights reliably in the photo.

    As for your other settings, to increase the DOF, use a smaller aperture. Yes, that means you will need MORE light, so turn up the power on the speedlight. Since you can figure the DOF with the DOF calculator, do the figuring before the gang shows up, so you will be ready. Draw some imaginary lines (or use the beads, or whatever) in which to pose the children. inform mother that they should be positioned within your imaginary posing box, and the DOF should be deep enough to get everything in focus (yes, including your props). If the DOF is deep enough to get the sled and the beads in focus, then any child within that area should be in focus as well.

    Good luck!
     
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  6. smoke665

    smoke665 TPF Supporters Supporting Member

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    I use duct tape X's stands up to the most persistent child. LOL Clone out what shows post
     
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  7. CherylL

    CherylL No longer a newbie, moving up!

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    Wow, lots of info I need to digest. Agree the BG should be wide and not tall. It is the width of the projector screen and I'll need to improvise. I had planned on getting adult photos sitting on a stool or bench too.

    I'll work practice the next few days with the 85 and various settings. Thank you for all of the info, much appreciated!
     
  8. CherylL

    CherylL No longer a newbie, moving up!

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    Thank you! I am humbled :)
     
  9. CherylL

    CherylL No longer a newbie, moving up!

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    For the kids I am using a red furry stool, small chairs and a rocking horse. The end of the pool table serves me as a guide, but will think about something on the floor if the kids are sitting or standing ground level.

    Thanks for the help!
     
  10. CherylL

    CherylL No longer a newbie, moving up!

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    I did notice that the lights would all appear at random. If I had a constant light instead of flash I could then up my shutter speed and spray a rapid fire of photos. Good idea on using beads as the box of focus. Thank you!
     
  11. Designer

    Designer Been spending a lot of time on here!

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    I don't understand. From what I understand about constant lighting is that it is usually not enough light to allow for a fast shutter speed. Maybe if you used constant tree lights instead of LED lights that might be better. (?)
     
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  12. Braineack

    Braineack Been spending a lot of time on here!

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    I really think you should reconsider using duct tape for the kids :p
     
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