EV Compensation -- I should know... but

cwgrizz

Senior Member
Challenge Team
Just about the time I think I am getting a grasp on the EV +/- compensation concept, I seem to develop a fog in the brain. Ha! I have read and watched videos to explain how the camera works with the exposure and the gray/grey figure, etc. For me common sense seems that if I have a very bright scene ie washed out bright sky, I would want to shift the exposure to the negative, or if I have a dark forest scene that I would want to brighten it up with a plus compensation. I know that I read that the camera sees the bright scene a compensates by moving what it thinks the gray point would be up on the scale and thus underexposing the shot so the rule is to go plus with the EV.

For me, I have not seen that work out. For the sake of illustration the bright sky scenario, when in Shutter Priority mode, 0 EV compensation the aperture is f9.0. Put in a +1 EV and the aperture opens (fstop decreases in number) which blows the sky scene out more. This is where I can't wrap my head around the written things I have read ie "Bright, go brighter" and "Dark go darker". Bright is the white sand or snow example I see most.

Saying all of this, I do seem to have better results with BIF by setting the EV +0.7 or so. The sky ends up blown out, but the bird is not just a black bird shaped blot.

I have been leaning toward the idea of ............... I don't know how I am leaning on this now. Ha! Please help me shape this in my mind with examples. Something that you may use for a rule on particular types of shots ie small dark bird in birght sky, light object in a dark woods, all dark, all bright...

Thanks, I really think I just have a mental block (happens when you get old, no wait, it happened when I was young too.) :shame:
 

cwgrizz

Senior Member
Challenge Team
Yes @FredKingston that would be OK if the shooting scenario was always the same, but with what I seem to be shooting most (BIF) it can be in many different directions and conditions. Clouds, bright sky, trees etc for backgrounds thus creating different lighting. I usually shoot "S" priority for BIF with a shutter speed of 1250 or 1600. The sky can vary extremely in the brightness, but it is still too bright for the dark birds. ISO is fixed, Shutter speed is fixed, so fStop is all that changes. The EV biases the aperture, but still lets it change for brightness. It is not a situation where I can shoot, look at results, adjust and shoot again. If I could do that then Manual would be the way to go.

And then there is the question, why have EV compensation on the camera if you don't use it. Ha! Again, I am just trying to comprehend how to use it because it is there. :rolleyes:
 

John!

Senior Member
It can be confusing I know, Maybe I can help.
Your camera meter does not know whether you are shooting a snow scene or a pile of coal. therefor it will try to expose every scene to an average of 18% grey.
Lets say you are shooting a snowy owl on a bright day with snow covered ground. This scene would be a lot brighter than than the average scene. To compensate for the bright scene you tell your camera that to overexpose by at least 1 stop, maybe even 1 2/3. Thats where the EV +1 comes from. Of course with the dark pile of coal every thing is just reversed.
By default the cameras meter will try to expose both scenes to be the same bright.

Hope this helps..

John
 

cwgrizz

Senior Member
Challenge Team
@John! Thanks, I know what you are saying. That is what I have read and watched someone in videos explain. In words and on paper it makes perfect sense. I completely understand what is being said, but........ where I am having problems is that I cannot seem to put it to practice. In other words, it doesn't seem to work as is being stated. Of course, I don't have a snow covered scene (So AZ doesn't get many snow storms. Ha!)

Let me put it another way. I can take a picture of the extra bright sky with the exposure as the camera decides it should be (no EV compensation) Shutter priority, ISO fixed, and the camera sets the aperture as an example of f9. The shot is not underexposed as stated it will be in all of the tutorials on EV compensation (because the 18% grey is guessed by the camera to be averaged), but in my estimation quite the opposite and overexposed. Of course in this situation if you add +1,2 or anything + it just exacerbates the overexposure.

Maybe I am still missing when to use or compensate. I know I can take three photos of the same scene using EV 0, +1, -1 and see the results as expected. +1 brighter, -1 darker from what 0 showed. If using something similar to the black coal (a line of thick pine trees) the exposure at 0 is dark (shadowed) so if I add -1 it just gets darker, but contrary to the 18% grey concept +1 pulls out the detail.

I hope this helps to illustrate my confusion and maybe give someone something that I am missing and bring my brain exposure to the correct value. Ha!

Thanks to all.
 
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cwgrizz

Senior Member
Challenge Team
I see people using it, but the photographed scenes (for me) are hard to determine why they put in -0.33 or something. Post processing can throw the "look at the picture and determine why EV compensation was used" out the window.
 

Michael J.

Senior Member
I need for my 55-300 -3 for my other lenses only on bright days, sunset I go for -7 or higher, Night photography too. Makes the scene more how I see it
 

Horoscope Fish

Senior Member
Let me put it another way. I can take a picture of the extra bright sky with the exposure as the camera decides it should be (no EV compensation) Shutter priority, ISO fixed, and the camera sets the aperture as an example of f9. The shot is not underexposed as stated it will be in all of the tutorials on EV compensation (because the 18% grey is guessed by the camera to be averaged), but in my estimation quite the opposite and overexposed. Of course in this situation if you add +1,2 or anything + it just exacerbates the overexposure.
Okay so let me use an example to make sure I understand what's going on. You are using Shutter Priority so your shutter speed is dialed in to something like 1/500 (just as an example). Your preferred ISO is also dialed in to, say, ISO 200 (or whatever). Exposure Compensation is at "0". You point your camera at a very bright sky, the camera selects f/9 as the aperture and you take the shot. You review the shot and it's over-exposed. If that's what's happening then I'd have to say something is not adding up.

To help people remember how to use Exposure Compensation, I tell them, "If it's too bright, go brighter (use +EV). If it's too dark, go darker (use -EV).

The only thing I can think of that might be fouling up this equation is Matrix Metering. Is that what you use primarily? If so, try doing some test shots using other metering modes and see if your experience with Exposure Compensation is the same. Simply put, +EV should be doing just that, giving you a a brighter exposure; while -EV should be giving you a darker exposure. From what you are describing however, this is not the case and we need to figure out why.
....
 

nickt

Senior Member
I'm getting confused here, just on the wording of the tip. I do understand how the compensation works. I've never really heard it put like that, but let me see if I follow the logic... This tip works out if the scene is generally bright AND the subject will get 'lost in the sauce'. That is, because of the generally bright scene, the main subject will get darkened up by the meter, possibly too much. So for bright scene, go + works. Or maybe a snow scene. Snow will certainly look gray, so + would whiten it up. That fits the tip too.

But I always thought of exposure compensation this way:
Positive compensation gives more exposure than the meter suggests. Negative compensation gives less exposure than the meter suggests. With that in mind, how will my main subject meter? Will he end up too dark because of bright surroundings fooling my meter? If so + compensation added. The tip is confusing because we have bright scene, but dark main subject. Example would be a bird in the sky or kids on the beach with sun behind them. Bright sky - dark bird, therefore + compensation.
Example 2 is a white cat cat sitting in a shady tree. White cat will get blown out when the meter balances the scene and brightens up the tree. So minus compensation added in for the bright cat.

In the two examples above, the 'important' things could reverse by personal choice. Maybe we want the clouds exposed, not the bird flying by. Maybe we want the tree leaves shown at their best, not the white cat.

Then there is another possibility that doesn't fit the tip... Do we simply want to lighten or darken the whole scene? For an extreme instance do we want to make a day scene look darker or a night scene look brighter? Simply add compensation for a dark scene to make it brighter or subtract exposure from a bright scene to make it look darker.

The bottom line question for my brain is "do I want the area of the scene that I am most interested in to have more exposure or less exposure?" Then I will just add or subtract compensation accordingly. The tip just doesn't work for me, but sometimes my brain is stubborn to follow the conventional path even though I end up in the right place. I'm more good with saying dark subject then add compensation. Bright/blown subject, remove compensation.

I hope I didn't confuse more.
 

gustafson

Senior Member
As a newbie, I have an even more basic question about when to use EC and what does the camera actually do when you apply EC. Arguably, one could control exposure by independently tweaking aperture, shutter speed, or ISO, or combinations thereof, so what are common situations when one needs to use EC? Also, what does the camera actually do when you use EC? Does it override the user-specified or auto ISO? (I can't imagine it overriding the user-specified aperture or shutter speed).


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cwgrizz

Senior Member
Challenge Team
As a newbie, I have an even more basic question about when to use EC and what does the camera actually do when you apply EC. Arguably, one could control exposure by independently tweaking aperture, shutter speed, or ISO, or combinations thereof, so what are common situations when one needs to use EC? Also, what does the camera actually do when you use EC? Does it override the user-specified or auto ISO? (I can't imagine it overriding the user-specified aperture or shutter speed).


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What it does can vary depending on what mode you are shooting in. For example, if shooting with "S" (shutter priority) the EC will change the aperture setting (OPEN or CLOSE it) depending on whether you add a + or - EC. IF ISO is set to AUTO, the ISO can change. If you are shooting "A" (aperture priority), the shutter speed will be changed up or down depending on whether you add a + or - EC. (Also ISO if in AUTO as stated before). If shooting in "M" (manual mode), EC will not do anything to your settings.

As to your question as to when to use it, I think it depends on your shooting style, camera being used, etc. Keep following this thread as I think we are going to get some of it sorted out. Ha! (Hoping so, in my case anyway.)
 

cwgrizz

Senior Member
Challenge Team
@nickt You have, in your post, pretty much mirrored my thoughts (confusion) and understanding perfectly. Thanks.

Today the weather is not cooperating to shoot any good examples because of the cloudy, rainy weather, but here are a few to try to illustrate. All shots are straight out of the camera (all neutral settings except Auto WB). The only adjustments were to resize and reduce resolution for posting here.

The first three shots are EV 0, EV +1.3, and EV -1.3 . They were shot hand held, but were pretty close to the same shot conditions.
EV0-DSC_2589x.jpg


This is shot as the camera decided it should be exposed. (Center Weighted Exposure)

EV+1-DSC_2590x.jpg

This was shot with the +1.3 EV. It is more washed out, which seems contradictory to the "Bright add +EV" rule of thumb. Ha!

EV-1-DSC_2591x.jpg

This was shot with the -1.3 EV. It for me looks much better and is contrary to the "EV rule of thumb."

After rolling this around in the empty space between my skull and my brain, I "think" I am beginning to see something come to light (pun intended. Ha!) The 0 EV shot is what the camera sees (probably off because of the 18% grey factor). The + EV is adjusting the camera so it sees what I am actually seeing (more or less, even if I don't like it). The - EV is adjusting the camera so it sees "what I want it to see." (More pleasing). I hope that makes sense to others, because I am still trying to convince myself of that. Ha!

Then to illustrate NickT's thoughts here is another shot using a -/+ EV adjustments.

EV+1-DSC_2597x.jpg

If it would have been shot with 0 EV the bird and post would have been a dark almost silhouette. The + EV washed out the sky more, but brought out the darker subject so it could be distinguished.
 

nickt

Senior Member
@cwgrizz I agree your -1.3 looks the best. I don't think we can put a good rule on this. It comes down to do you want more or less exposure than what your meter says.
@gustafson Think of the +/- compensation as an offset to your camera's meter. Plus compensation makes your meter need more light to be satisfied. Minus makes it need less light to be satisfied. Its just a convenience feature, you could do this manually. It works differently in different modes. In aperture mode, +1 compensation will give you one slower shutter speed for more exposure. In shutter mode, +1 compensation will give you one step wider aperture (if it can). In manual, it will just change when you reach the happy spot on the viewfinder meter, just a reference to look at. In manual with auto iso, it will change the iso up/down to suit your request. In A or S with auto iso, it should work similarly, basically fudging your meter up or down to get you more or less exposure and auto iso will kick in depending on how it is set.
 

gustafson

Senior Member
Thanks for your replies, @cwgrizz and @nickt. Follow up question: does auto ISO work in M mode with vintage manual lenses that cannot meter? I didn't think so, but would be thrilled to hear otherwise.


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nickt

Senior Member
Thanks for your replies, @cwgrizz and @nickt. Follow up question: does auto ISO work in M mode with vintage manual lenses that cannot meter? I didn't think so, but would be thrilled to hear otherwise.


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Just on general principals I want to say no, but I dont know how it behaves.

Edit: It might work. I just took my lens off the d7100. With auto iso, I pointed the body with no lens at the ceiling light. I got a nicely exposed blur at iso 100. I pointed at a darker area and took another shot and got a nicely exposed blur at iso 6400.
 
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Horoscope Fish

Senior Member
The first three shots are EV 0, EV +1.3, and EV -1.3 . They were shot hand held, but were pretty close to the same shot conditions.

View attachment 184934

This is shot as the camera decided it should be exposed. (Center Weighted Exposure)

View attachment 184933

This was shot with the +1.3 EV. It is more washed out, which seems contradictory to the "Bright add +EV" rule of thumb. Ha!

View attachment 184935

This was shot with the -1.3 EV. It for me looks much better and is contrary to the "EV rule of thumb."
Okay, let me see if I can help clarify...

Your first shot is not particularly bright; really it's a pretty average scene if a little on the "high key" side (more lights than darks but nothing that's particularly light or dark), so it exposed correctly. Using Exposure Compensation "brightened" the already properly exposed photo. You might find the shot more pleasing with an exposure adjustment but when I open your first shot, without any compensation applied, the histogram confirms the shot is properly exposed.

So now, let's switch gears for a moment and imagine you are shooting a polar bear on a pristine bank of white snow under a full, bright sun. The camera meters the scene and you take the shot. Chances are all that snow, and your white polar bear, are going to look a bit grey. Maybe not 18% grey card grey, but you're probably not going to see pristine whites like you are seeing with the naked eye. So... What to do? Well, to get a nice white polar bear and nice white snow in this very bright scene, you need to INCREASE your exposure. When I say, "If it's too bright, go brighter!", what I mean to say is, if the scene looks "too bright" to your eye, INCREASE your exposure so it will not look too dark on your camera. How much you need to increase the exposure so it will match up with what you are seeing with the naked eye will vary with the particulars of each shot but the concept is the same: The brighter the scene is, the more the camera will want to bring down the exposure to more closely match middle grey. You compensate for this by INCREASING the exposure/brightening the photo.

I think we also need to be clear that correct exposure is often different from aesthetically pleasing exposure. By correct I mean that there are no blown out pixels, neither in the highlights, nor the shadows; only that the entire range of luminosity has been captured. Technically correct exposure may not be what we want, that's a matter of personal preference for each shot, but the meter's job, really, is to be consistent. Since it can't read our artistic mind it's up to us to understand how the meter behaves and too adjust for that so the exposure we get is the exposure we want. And we can only do that if the meter gives us a consistent platform from which we can base our calculations.
.....
 
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gustafson

Senior Member
As regards @cwgrizz's shot of the bird in an earlier post, not sure what type of metering was being used, but seems like that would be a good case to use spot or center-weighted metering (as opposed to using matrix metering and then applying EC).


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