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Noise in back-lit shots
  
 
rek101
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p.1 #1 · p.1 #1 · Noise in back-lit shots


I take a lot of backlit shots with windows behind my subject and I notice that photos look a lot noisier than a photo taken at the same shutter speed and aperture of non backlit subjects. The noise isn't just in the shadows or any one area...it's across the board.

Are there certain conditions that produce cleaner or noisier images at comparable ISOs? I use a 5d mark III and it's a tiny bit worse with this camera than my old 6d, but very similar.



Nov 07, 2017 at 01:47 PM
dhphoto
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p.1 #2 · p.1 #2 · Noise in back-lit shots


Are you using flash or reflectors to fill-in? If not then the overall contrast of the scene may be beyond the ability of the sensor to record without introducing noise.

In addition if you pull or push the files a lot in processing it increases the noise. A sample would be helpful.



Nov 07, 2017 at 02:45 PM
rek101
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p.1 #3 · p.1 #3 · Noise in back-lit shots


dhphoto wrote:
Are you using flash or reflectors to fill-in? If not then the overall contrast of the scene may be beyond the ability of the sensor to record without introducing noise.

In addition if you pull or push the files a lot in processing it increases the noise. A sample would be helpful.


Thanks for the response. These are shots without flash or any kind of fill in. The only way I've found to avoid it is to use flash.

What I don't quite understand is how noise works in these kinds of situations. If I'm at ISO 800 for example which is usually pretty clean, why does backlighting create noise? Assuming I want to take a few shots with the window blown out and my subject correctly exposed, is there a way to produce a shot without excessive noise with natural light? What settings would you suggest?



Nov 08, 2017 at 04:58 AM
dhphoto
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p.1 #4 · p.1 #4 · Noise in back-lit shots


rek101 wrote:
Thanks for the response. These are shots without flash or any kind of fill in. The only way I've found to avoid it is to use flash.

What I don't quite understand is how noise works in these kinds of situations. If I'm at ISO 800 for example which is usually pretty clean, why does backlighting create noise? Assuming I want to take a few shots with the window blown out and my subject correctly exposed, is there a way to produce a shot without excessive noise with natural light? What settings would you suggest?


Somebody technical will tell you the electronics of it but it's just the same as with film, you have a limited amount of contrast a sensor can resolve comfortably, be outside that and you will pay a penalty with noise and image quality.

Digital is usually acknowledged as having similar contrast limitations to slide film, which was always less tolerant than negative film.

The only way to deal with this that I know of is to somehow lower the overall contrast and the two usual methods are fill-in flash and/or reflectors to put some light into the darker areas. For static subjects you can bracket and combine images too

Digital is a wonderful medium for photography but it's still not perfect and Canons generally have a bit less flexibility than some other makes. I know how to deal with this so it doesn't matter all to me but many will disagree

Really it's just a case of learning, trial and error



Nov 08, 2017 at 07:47 AM
melcat
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p.1 #5 · p.1 #5 · Noise in back-lit shots


rek101 wrote:
What I don't quite understand is how noise works in these kinds of situations. If I'm at ISO 800 for example which is usually pretty clean, why does backlighting create noise?


My guess would be that the image is grossly underexposed, so the raw converter is adjusting the exposure. If the background is blown out it will also end up posterized (i.e. visible bands in the gradients), and one way tio make that less obvious to humans is to add noise; a really smart raw converter might do that.

Starting with "Process 2012", Adobe's raw converter silenty tries to fix bad exposure and contrast problems. Try selecting "Process 2010" or earlier to really see what's going on with your raw image. (There is also at least one specialist software tool you can get.) It suits Adobe's commercial aims not to always tell the user when an image has problems.

Assuming I want to take a few shots with the window blown out and my subject correctly exposed, is there a way to produce a shot without excessive noise with natural light? What settings would you suggest?

Spot or partial meter on the subject. You can also meter the background, count stops (the 1-series camera can display it graphically in the finder) and thereby determine whether it will be blown out.

If there simply is not enough dynamic range for both subject and background, there are two common remedies:

1. More light on the subject.
2. Use two exposures and combine them in post.

If you've ever seen a TV journalist doing a piece to camera outdoors, e.g. in front of a parliament building, you'll notice that on a bright day they have a portable light on a stand. And, talking heads on news shows often appear in front of a videoscape of the city, which is edited in in real time: they're actually sitting in front of a "green screen".




Nov 08, 2017 at 08:29 AM
rek101
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p.1 #6 · p.1 #6 · Noise in back-lit shots


Well if I spot meter on the face and expose it correctly, the window is of course blown out which is what I wanted. What I didn't understand is why the face is still very grainy. I was hoping to understand the rules I should follow to avoid this effect.

To check exposure on the face, I usually crop just the face in lightroom and without any adjustments in post, the face is correctly exposed. There is still so much noise in the face that it looks like it was taken at ISO 20,000.

It sounds like if you have this kind of extreme contrast in an image, there is another reason noise is introduced that isn't strictly because you needed to increase the ISO to create a proper exposure. My goal isn't to start some kind of Nikon V. Canon discussion. I'd just like to know what settings I can use to minimize the effect.

Would ISO 100 even help enough to make it worth using? Would trying to block the window a bit solve the problem or would I need flash? I can do all these experiments myself, but I thought maybe someone more experienced might be able to chime in.



Nov 08, 2017 at 02:22 PM
Pixel Perfect
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p.1 #7 · p.1 #7 · Noise in back-lit shots


This strange, what camera are you using. I have never seen such noise on the subject if I expose for the face. The noise came with all but the most recent sensors, when you exposed for the background and the subject was underexposed and you lifted the exposure for the subject. For the older sensors earlier than 80D, 5D4, 1DXII, you could really only lift shadows by 2 stops before noise and banding became intolerable.

Can you post and example with EXIF data shown?

Edited on Nov 09, 2017 at 11:28 AM · View previous versions



Nov 09, 2017 at 04:26 AM
melcat
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p.1 #8 · p.1 #8 · Noise in back-lit shots


rek101 wrote:
To check exposure on the face, I usually crop just the face in lightroom and without any adjustments in post, the face is correctly exposed
(my bolding)

The thing is, by default Lightroom does adjust with recent Process Versions, even if you don't move the slider. Assuming the histogram works the same way as Camera Raw's, it shows the distributiiion after adjustment, but only of the pixels within the crop. I had a play with one of my images, for which I had used Process 2010, that had a similar blown-out background. Moving the crop between background and subject did not alter the global exposure adjustment, but it did change the histogram. Then I changed the Process Version to the current one (2017) and it brought the background down so that it no longer clipped, and it also substantially raised the midtones in the subject.

If my subject had been underexposed then the adjustment would have been more.

There is still so much noise in the face that it looks like it was taken at ISO 20,000.

As Pixel Perfect says, this does seem very odd. If you shot at ISO 400, that's around 6 stops.

Would ISO 100 even help enough to make it worth using?

ISO 100 will give you the largest dynamic range on (most?) Canon cameras. Increasing the ISO causes more amplification to be done in the camera, which increases noise, which reduces dynamic range. The rule is: use the lowest native ISO you can which does not underexpose the subject.

Would trying to block the window a bit solve the problem or would I need flash?

Your first remedy as a stills photographer should be fill flash. You are correct in that doing something about the window would also work in theory, but in practice it's physically a pain and I'd never do it for stills. When film crews rent a house for location shooting they will often attach big sheets of neutral density filter plastic to the windows to do exactly that.


Edited on Nov 09, 2017 at 09:31 AM · View previous versions



Nov 09, 2017 at 08:16 AM
dhphoto
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p.1 #9 · p.1 #9 · Noise in back-lit shots


An example picture would really help


Nov 09, 2017 at 08:23 AM
rek101
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p.1 #10 · p.1 #10 · Noise in back-lit shots


Thanks. When I ahoot in this location, I use flash most of the time. But I also like to turn it off sometimes and in situations where there’s someone in front of a large sindow, I meter with spot just on their face or off the floor or a nearby wall. I’m usually about four stops above what I would have been had I just pointed and shot. The photo has a lot more noise in the face than it otherwise would have had. I think the gentleman who shared the film slide comparison helped me understand what I’m dealing with. Thanks again.


Nov 09, 2017 at 01:50 PM
 

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TeamSpeed
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p.1 #11 · p.1 #11 · Noise in back-lit shots


A shared raw will help immensely with the ability to suggest settings and process alterations to make this type of situation a bit cleaner. There are alot of theories here, but an actual file would be great, raw preferred.


Nov 09, 2017 at 02:51 PM
AmbientMike
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p.1 #12 · p.1 #12 · Noise in back-lit shots


Noise is definitely more noticeable in some situations than others. More visible in a smooth oof area than textured area, in general.


Nov 09, 2017 at 07:36 PM
rek101
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p.1 #13 · p.1 #13 · Noise in back-lit shots


Why do people keep asking for samples. Pick up your camera, spot meter something and take a backlit shot in strong sunlight at ISO 800 and look at it. You'll see that such a scene will produce far more noise than a non backlit ISO shot. Then you'll be happy you read the post from the person who wrote the comment that referenced film. At least that was helpful.


Nov 10, 2017 at 03:54 AM
AJSJones
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p.1 #14 · p.1 #14 · Noise in back-lit shots


rek101 wrote:
Why do people keep asking for samples. Pick up your camera, spot meter something and take a backlit shot in strong sunlight at ISO 800 and look at it. You'll see that such a scene will produce far more noise than a non backlit ISO shot. Then you'll be happy you read the post from the person who wrote the comment that referenced film. At least that was helpful.


Because something does not add up. You say you meter correctly and use ISO 800 but it looks like the noise from ISO 20,000. Those statements are not compatible. That’s why “show and tell” is important. When I meter correctly and use ISO 800 I don’t get noise like 20,000 in the area I metered for, even when some other parts of the image are blown out.



Nov 10, 2017 at 05:26 AM
melcat
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p.1 #15 · p.1 #15 · Noise in back-lit shots


rek101 wrote:
Why do people keep asking for samples. Pick up your camera, spot meter something and take a backlit shot in strong sunlight at ISO 800 and look at it. You'll see that such a scene will produce far more noise than a non backlit ISO shot.


The example shot I used in my post about the Process Versions experiment above was shot at ISO 800. I don't see terrrible noise; it is about right for this camera (a now rather old !D Mk III, 10 year old technology).

It is very unlikely that the spot meter on your camera is broken, since on Canon cameras spot vs. the other metering patterns is just done in firmware and uses the same meter. (That was not the case on a camera from another brand I used to own, where indeed one meter could break, and I know of a case when it actually did.)

The thing you need to understand about spot metering is that, unlike for example evaluative metering, it doesn't take into account anything in the rest of the frame, If you thought it meant "I point the spot at the subject and the camera figures out an overall correct exposure for the image", you were wrong. If the thing you point it at is not 18% grey, you will get a wrong exposure. When working with spot, you need to be able to estimate the whiteness (or, in Ansel Adams's terminology, the "zone").

Ockham's Razor suggests you just aren't exposing correctly. My suggestion, if you can't diagnose it via the raw file, is to bracket. You will need to do so by more than the default 1 stop in each direction, since clearly you seem to be around 5 stops out.

And that's why people are suggesting you post a raw file.

Then you'll be happy you read the post from the person who wrote the comment that referenced film. At least that was helpful.

Ex-transparency shooter here. Like digital, if you didn't want highlights blown out, you would "expose for the highlights and let the shadows fall where they will". You could spot meter on white and then set exposure to +2⅔ stops—I even owned a camera with a dedicated button to do that. Spot metering always involved estimating the tonality as well as the actual metering, and that needed experience.

So, for example, if your spot meter catches a white bridal veil, you'll be around 3 stops underexposed if you don't adjust the exposure.



Nov 10, 2017 at 08:48 AM
dhphoto
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p.1 #16 · p.1 #16 · Noise in back-lit shots


melcat wrote:
The example shot I used in my post about the Process Versions experiment above was shot at ISO 800. I don't see terrrible noise; it is about right for this camera (a now rather old !D Mk III, 10 year old technology).

It is very unlikely that the spot meter on your camera is broken, since on Canon cameras spot vs. the other metering patterns is just done in firmware and uses the same meter. (That was not the case on a camera from another brand I used to own, where indeed one meter could break, and I know of a
...Show more

Quite. You're just restating what I said earlier, there are some ways you can sort this contrast issue but unless we see the actual shot the thread is just going round in circles



Nov 10, 2017 at 09:18 AM
rek101
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p.1 #17 · p.1 #17 · Noise in back-lit shots


The guy who understood film does not need a raw file. I took 100s of photos. Some have overexposed faces, some have underexposed faces, and not one of those faces looks even remotely as clean as as the faces in the flash images also taken at ISO 800. These aren't closeups of a back-lit face in front of diffusely lit window. This was a room full of people taken at 24 mm with the main subjects standing directly in front of a large window with bright sun pouring in. I exposed for the faces of the main subjects just to see what would happen. I liked a lot of what I saw, but I'd like to know about the noise issue so I can go back and try again with better results.

If you've actually experienced this yourself and have some tips or ideas, I'd love to know some settings or best practices to be able to shoot some of these types of shots without flash so I'd have more variety. I posted in Canon assuming that dynamic range is the thing I've heard is different about Nikon and Sony so I wanted settings and tips that would work for a 5d series camera or similar.



Nov 10, 2017 at 01:31 PM
TeamSpeed
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p.1 #18 · p.1 #18 · Noise in back-lit shots


rek101 wrote:
The guy who understood film does not need a raw file. I took 100s of photos. Some have overexposed faces, some have underexposed faces, and not one of those faces looks even remotely as clean as as the faces in the flash images also taken at ISO 800. These aren't closeups of a back-lit face in front of diffusely lit window. This was a room full of people taken at 24 mm with the main subjects standing directly in front of a large window with bright sun pouring in. I exposed for the faces of the main subjects just to
...Show more

It is not a film thing, but rather a settings thing, and that is why we need the raw file to see your exposure and settings. This also isn't a dynamic range thing either. The only time dynamic range comes into play here is if you want to lower the background to get back detail and raise the foreground to pull up detail, without blowing out highlights or have shadows in the deep recesses of black, or produce unsightly noise. What you want isn't this, but rather just an exposure for the people in the room so they are clear, and the backgrounds will blow out.

Of course these shots aren't going to look as clear as fill flash, because light creates detail. If light is coming from behind and you don't add more light to the front, your results won't match flash shots. That is to be expected.

Finally noise ONLY results from high ISO values, or from post processing where shadows are brought up afterwards, digitally enhancing any noise that is there from the sensor. It doesn't result from contrasty shots.

Why not supply a raw to really garner good input? It's not difficult to do so.

By the way, the guy that gave you the film/contrast thing did indeed ask for a file. Preferably one that was not altered from the camera and has the exif intact, or a raw which gives us the same thing.

dhphoto wrote:
An example picture would really help





Nov 10, 2017 at 01:53 PM
dhphoto
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p.1 #19 · p.1 #19 · Noise in back-lit shots


rek101 wrote:
The guy who understood film does not need a raw file. I took 100s of photos. Some have overexposed faces, some have underexposed faces, and not one of those faces looks even remotely as clean as as the faces in the flash images also taken at ISO 800. These aren't closeups of a back-lit face in front of diffusely lit window. This was a room full of people taken at 24 mm with the main subjects standing directly in front of a large window with bright sun pouring in. I exposed for the faces of the main subjects just to
...Show more

I used film professionally for over two decades and I have already answered your question as have several others, you are beginning to sound like a troll.



Nov 10, 2017 at 02:09 PM
rek101
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p.1 #20 · p.1 #20 · Noise in back-lit shots


dhphoto wrote:
I used film professionally for over two decades and I have already answered your question as have several others, you are beginning to sound like a troll.


No you babbled about something that didn't help me in any way. I wanted help, not someone's babbling.



Nov 10, 2017 at 02:38 PM
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