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FORUMS Photography Talk by Genre General Photography Talk 
Thread started 25 Mar 2016 (Friday) 14:14
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Is it White Balance or Exposure fooling me?

 
Roxie2401
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Mar 25, 2016 14:14 |  #1

I've been give a project to document our local cemetery. I'm using a Canon 5d MK III with either my 24-105L or 100mm Macro L. I was shooting in Av mode, usually f/8 and with spot metering.

My images are consistently dark and I'm beginning to wonder if its because 90% of my subjects (Headstones) are gray granite and that's fooling the metering, which I think is calibrated to an 18% gray.

I'm going to switch to full manual, but wonder if I'm going to have to over expose or use an Exposure Compensation setting.

I keep thinking this is the 18% gray of the meter but could it also be the White Balance, which I think also uses a gray scale?

Seems like a pretty simple problem and I've forgotten the basics of how the camera is set up by Canon.

Who knew I'd be shooting all gray subjects!

Thanks




  
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Luckless
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Mar 25, 2016 15:26 |  #2

Sounds like you may want to go back and read up on using an in camera meter to better understand what is going on. (https://photography-on-the.net/forum/showthre​ad.php?t=89123 is the frequently suggested reading on this site I believe.)

Spot metering is useful when you want to pick a specific part of the image and then decide where on your 'exposure line' you want to place it. Your exposure line ranges from the darkest black to the brightest colour/white of the image. The meter expects a mid-tone somewhere between the two, because on average most photos will be roughly balanced between very black and very bright.

Of course, not all photos are actually the same, and frequently you need to account for a scene being brighter or darker than what the camera has to assume it actually is. (The camera meter is after all just a very very basic computer, it has no idea if it is pointing at coal or fresh snow, so YOU have to account for that and feed it the suitable adjustments.)

The spot meter makes it that much more critical for you to evaluate and adjust things correctly. Personally I tend to ignore the mid tones while using a spot meter, and instead focus on what parts of the photo are blowing out at either end. The mid tones are in the middle, and they'll be recorded one way or the other, but the shadows and highlights can get crushed very easily in digital, so instead I'll pick the points that I want to be my highlights, and make sure I'm using settings that place them near the far right, but not off the edge.


You can also fall back on using "Sunny 16" and manually setting things while totally ignoring your meter. With digital it works well if you combine Sunny 16 and learning to read the histogram. (Digital doesn't have the dynamic range between light and dark to give you as much of a safety net as most film will. And since you have a computer with a detailed signal analysis toolset in your hands... Well, you may as well take advantage of learning to read what a histogram of a photo tells you. I strongly suggest using the RGB rather than general histogram.)


Long story short: Don't 'chase the needle', 'Set the needle'.


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Roxie2401
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Mar 25, 2016 17:00 as a reply to  @ Luckless's post |  #3

Thanks. You mentioned "coal or snow." Isn't there a compensation needed for snow so it doesn't appear "gray" due to the meter being calibrated for that very same 18% gray?

Oh, and I did start out with Evaulated metering but switched to spot since I as more interested in the Cemetery Headstones and not the surrounding areas.

Really appreciate your input.




  
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MalVeauX
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Mar 25, 2016 17:13 |  #4

Heya,

So white balance has nothing to do with exposure. If you're saying your photos are too dark, they're just under-exposed. The grey stone is brighter than you think, the color of it doesn't matter.

I would not use spot meter.

I would use evaluative or partial. I typically use partial (to get an average of everything in the center of the composition basically).

But ultimately I would shoot manual and I would expose to the right by about +2/3rds of a stop in RAW. This gives you a lot more editing room later. Use Evaluative or Partial in manual mode, and adjust exposure values until you are at +2/3rds to the right of 0.

Very best,


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Luckless
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Mar 25, 2016 17:18 |  #5

The compensation is exactly what you need to consider. The camera meter is 'dumb'. You point it at something and it says "Assuming that is the gray midpoint I'm calibrated for, then this is the exposure you need" (Or, "you're above/below that point with these settings" if you're in manual settings mode.)

You however have to say "That's nice, now adjust the exposure to make it brighter or darker". The camera assumes that everything in the world is basically made of grey cards, and it needs you to hold its hand and tell it how to adjust to correct for things.

How you do these adjustments depends on how you want to shoot and what kind of lighting you're working in. If I were doing a documentation style series of photos for a grave yard then I would use manual mode and take my grey card to meter off for my base settings. Most of the stones are nicely aligned, and should be in the same light, which makes your settings from one stone to the next fairly reliable. Just watch out for changes in light, such as shadows or large light coloured items throwing more light into the scene. (Also if you go from a dark near black granite to a bright marble or limestone, then double check that you aren't clipping highlights or losing shadow detail.)

Good luck with your project.


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Wilt
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Post edited over 4 years ago by Wilt. (2 edits in all)
     
Mar 25, 2016 17:47 |  #6

Look at this Macbeth Colorchecker card, at the greyscale steps in the bottom row...

IMAGE: http://i69.photobucket.com/albums/i63/wiltonw/Principles/Neutral%20balanced%20density_zpsij3ulm4i.jpg


  1. A gravestone which is the tone of Square 3, if metered, the result will underexpose your shot by -0.9EV
  2. A gravestone which is the tone of Square 5, if metered, the result will overexpose your shot by +1.2EV
  3. Only if you metered a gravestone of the tone of Square 4 (the legendary 18% grey) will you be about right on your exposure.


Therein lies the problem, so the solution...
  • So you need to use EC +0.9EV (if such a setting were available on the camera) to meter square 3 and correctly expose your shot. Think "my target is +0.9EV brighter than midtone")
  • You would need to use EC-1.2EV (if such a setting were available on the camera) to meter square 5 and correctly expose your shot. Think "my target is -1.2.EV darker than midtone")

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PhotosGuy
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Mar 26, 2016 08:03 |  #7

I'm going to switch to full manual, but wonder if I'm going to have to over expose or use an Exposure Compensation setting.

Try this: Need an exposure crutch?

And for those who ask "Why?": Post #47


FrankC - 20D, RAW, Manual everything...
Classic Carz, Racing, Air Show, Flowers.
Find the light... A few Car Lighting Tips, and MOVE YOUR FEET!
Have you thought about making your own book? // Need an exposure crutch?
New Image Size Limits: Image must not exceed 1600 pixels on any side.

  
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Roxie2401
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Mar 26, 2016 12:01 |  #8

Hey Thanks so Very Much!

I had the feeling the gray granite headstones was probably a factor in what was going on - and the color checker discussion confirms that. Wilt, thanks. And the "Shooting to the Right" discussion and the thread was a big help, Photo Guy.

I knew that when I had to adjust all the shots in LR, I had better ask the question. Wasn't sure if White Balance was entering into this, too, but knew the exposure was being influenced by the gray stones, especially when the overall shots in the cemetery were looking correct.

Best place to get answers - thanks to everyone for the input (EC and Metering) as well.




  
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Is it White Balance or Exposure fooling me?
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