Getting grain on photos part 2

[bunkieboy]

I'm the same guy who earlier posted about getting grain and a pigment look on some photos after enlarging a picture using the F button in Libary in windows 5. I could not figure out how to respond to Jim Hess's post and include a photo, so I started a new post. The picture attached was shot at iso 1600 using raw and upping the exposure considerably in library. I can't figureout  why my horizontal shots, using the same iso, come out okay. Obviously, when you use a bounce flash in a relatively high ceiling that isn't white, your vertical shots are going to get a lot less light. Any ideas on what went wrong and whether with RAW you're advised to shoot around 400iso since you can up the exposure in LR?

Thanks, Al.

[GoldingD]

What was the ambient lighting?

Flourecent? Including LCD

Incandansant? Not including LCD

From outside?

[bunkieboy]

Thanks for your response, David. The lighting was very low light incandescent from the ceiling. I'm going to be shooting something soon in a country club function room with not bright lighting and I wanted to test out if it is true that in RAW you can underexpose but get a good picture by increasing exposure in LR.

[Conrad_C]

You should look up whether your camera has an "ISO invariant" sensor, because that will answer the question of whether it's better to shoot at the correct exposure at high ISO, or to set a low ISO, underexpose, and boost it later in software. The sensor type determines that.

Raw works better than JPEG when increasing exposure for a different reason: Because the raw image has cleaner, less processed data that's easier to process for noise reduction. Part of the problem with JPEG compression is that to make the file size so much smaller, shadow detail is one of the places where severe compromises are made, and if you increase exposure of a dark JPEG you'll see those compromises right away and it won't be just noise.

JPEG or raw, the problem is that the bits in a digital image are not distributed evenly from dark to light; it's a nonlinear response. And the inconvenient thing about that is most of the bits are devoted to the lightest tones, and the fewest bits are in the shadow tones. So, if you have to shoot in a situation where you can only underexpose, the camera ends up putting most of the tones you want down in the shadows where the digital file uses the least amount of bits (the least amount of tonal detail or resolution) and is noisiest.

When you increase exposure in any photo editor including Lightroom, you don't actually increase the noise. You only make the same existing shadow noise more prominent. If you shoot slightly over correct exposure so that you have to reduce exposure in software, you push the existing noise down and make it harder to see. (It works the same way in audio, when you set recording levels to get the signal as far up away from the noise floor as you can. You want to optimize your signal-to-noise ratio.)

If there is any way for you to work out a lighting technique that puts the right amount of light on the subject consistently, like perfecting a bounce technique with a powerful enough flash, then you won't have to raise exposure in software, and the noise won't become more obvious.

[GoldingD]

Just how much sharpening was applied and what sort of masking. That noise could be by aggressive global sharpening. Have you treated all photos the same?

But, rethinking, you applied a lot of exposure increase (a misnomer in lightroom, that slider is better called brightness) could have added lots of noise. Abut why different? Do you have to apply as much of an increase to the other photos?

[bunkieboy]

I have no idea what sharpening is. Thanks for mentioning it, I see a listing of it in my LR help book. I'll read it, but you might save my ass by telling me how to set an average default setting for sharpening. Colud you just tell me how high you dare going with your ISO without getting noticeable grain? I'm thinking 800 is high enough.

[Tony_See]

Maybe you aren't throwing enough light at this in the first instance? You might need more than one light source to pull this off.

I disagree that you get more light on the sensor in Landscape vs Portrait format BTW

Have you used a diffuser on your flash?

I can see the sharp bright reflection in the subjects glasses that to me indicate you might not have . . .

[bunkieboy]

Thanks for responding, Tony. As I've said up above, I'm trying to see if you really can birghten underexposed RAW shots and make them look "normal". I plan to do documentary shooting so my flash will have to be my light source. If you know of some innovative way to shoot verticals beside twisting your flashing and having the flash bounce off the ceiling, I pray you will tell me. I do have one of those devices where you can shift your camera without moving the flash, but those "in the know" say only amateurs use them (they're also awkward). I don't get "landscape vs. portrait". Is that some setting on my camera I should be concerned with.? I don't use a diffuser, just an index card reflector held to the flash with a rubber band. I have a "cap" diffuser (it's like putting a lid on the flash top. Maybe I'd do better with verticals with a bubble diffuser? Would I still get the non-flat quality I get on horizontals with my index card?

[Jao vdL]

Landscape=horizontal, Portrait=vertical

[Jao vdL]

Yeah you have to rotate the flash head when you switch horizontal to vertical or you won't get any ceiling bounce if you are relying on that. There is no simple solution to that but for rotating it if your flash is attached to your camera.

[Jao vdL]

What you are seeing is cmpletely expected for the exposure you used and the older crop sensor camera (a Canon Rebel T5i). You used ISO 1600 and applied an exposure adjustment of +1.65. Effectively this means you used an ISO of around 5000. You will see a lot of noise with this sensor at that sort of ISO. You also did not really work the noise reduction as the luminance noise reduction is still at zero. You need to zoom in to 1:1 and work the noise reduction and sharpening sliders to get optimal results from this original that simply received too little light.

Ultimately, you simply need more light (it looks like your flash did nothing to light up your subject in this case), a better sensor, or better lenses in these circumstances. You could also open up your aperture more. You were using f/8 and the lens you were using can go to f/3.5, which is a 2.5 stops improvement and would allow you to lower your ISO and your flash to be more effective. You loose depth of field but with this image that wouldn't have mattered much. Lastly what likely happened in this case is that you are  bouncing of a far wall (the shadow to the right of the person suggests that the bounce is somewhere far to the left) instead of the ceiling. You need to play with the flash intensity more (set it manually and experiment) and make sure you rotate the flash head up when switching between portrait and landscape. Or also use a small diffuser card affixed to the back of the flash so that you also bounce some light directly to the subject and not just bounce it. A business card and a rubber band can do wonders for this if your flash doesn't have this built-in.

In the sort of circumstance you are showing I am usually more around f/4, ISO 400 or 800 and 1/60s and make sure flash intensity is enough and I generally use some TTL mode for the flash intensity. If you can't bounce anywhere, let the ISO creep up but know you'll have to work the noise reduction to make the images look good.

Lastly, you should always aim to expose your images right in camera. Most cameras nowadays have ISO invariant noise. This means that shooting at ISO 400, and increasing the exposure in post by 3 stops will give exactly the same results as shooting the same image with the same shutter and aperture at ISO 3200. With the difference that in the first case the image will look completely black on the back of your camera while in the second it will look normal. That's a significant advantage in the field. So if you have to shoot high ISO because you don't have the light, low enough f/stop lenses, or powerful enough flash, do it. There is no point in lowering the ISO. You will not get less noise.

[JP Hess]

Others will probably disagree with me. But I don't think the flash is really benefiting here. I would not use it. I would push the ISO harder and use existing lighting. Open the f-stop and then use the noise reduction features in Lightroom. It would eliminate the reflection in the eyeglasses. And I really think if you work with the images you would be able to achieve just as good of results as trying to work with a single underpowered flash. My granddaughter is a wedding photographer, and is a proponent of the existing light photography. I have been able to get good existing light images with my D7100 set at ISO 6400. Yes, there is a little grain, but it isn't all that distracting. Not as distracting as glaring reflections in eyeglasses.

[Jao vdL]

I actually completely agree. If you don’t have enough flash power you’re better off just using available light using fast lenses and working the noise reduction. Flash can be done well but you need to have enough and be able to bounce to diffuse it or diffuse in other ways that are usually not practical in an open setting. I routinely go 6400 and higher but it takes some attention in post processing.

[JP Hess]

For example, here is a photo of my granddaughter taken at ISO 6400, no flash, existing light. I thought that, as far as the noise was concerned, it was more than acceptable.

 

[bunkieboy]

The picture looks good. I would like to thank all you helpful people with your wonderful posts. I learned a lot. I think I have solved the problem of the grain and strange patina I got (if that is the word). The problem was, I was increasing my exposure using Library. Oce I got into Develop and raised the exposure with the slider, the problem ended. Again, the problem was the grain and pigmentation I got when I hit F to enlarge a picture on my screen. The picture looked fine until the "loading" ended. Thanks again for the help---you must know what it is like to have an important shoot come up and suddenly you get this problem. Al Marotta