Finally, I Understand Everything. Again

A while back, I wrote a piece in which I revealed that I had learned everything there was to know about ISO and noise reduction. Now, of course, I have to retract all that.

I guess I should start out by saying the biggest obstacles I have faced in photography have been noise and dynamic range.

What is dynamic range? More or less (probably less), it’s the difference between the brightest and darkest parts of a photo. If you shoot a photo of a pile of coal with the sun peeking out behind it, your photo will have a high dynamic range. Because cameras can’t handle this as well as eyes can, you are likely to end up with a black, featureless pile of coal or a huge, completely white area near the sun.

Dynamic range often presents problems when you shoot outdoors, because the sun is incredibly bright. It may not be obvious to you how bright it is, because your eyes can see a huge dynamic range, and they adjust when you move from bright surroundings to dark ones, but it is extremely bright. That’s why you can’t be outside on the planet where your species was created without taking measures to avoid injury from the light.

Imagine you are shooting your child, and there is a wall behind him next to a lamp. if you adjust your camera to pick up your child’s features, the texture of the wall may be completely lost.

As for noise, it is caused by insufficient light. Pretty simple.

Your camera uses ISO to deal with noise. Forget what ISO stands for. Not helpful. It means “amplification.” At ISO 100, your camera doesn’t amplify anything. At 200, it applies a factor of two, and so on. Amplification is not magic, so the amplified version of your photo will be grainy where the camera has to fill things in. Grain can be so bad it ruins a photo.

A high ISO does not make your camera more sensitive. It just amplifies whatever signal the sensor captures.

Because of noise, fast lenses are better than slow ones. They let more light in, so you get more signal per unit of noise. They let you get better pictures than slow lenses take in poor light.

Not long ago, I concluded that fast lenses were very important, and I still believe that. I shoot mostly indoors, and there have been many times when slow lenses held me back.

Later on, I became more familiar with editing software, and I learned that Photolab is the unrivaled king. It can take a noisy photo Lightroom can’t help and make it look so good, it will look like it was never noisy. This allows you to use slower lenses, shoot in worse light, use tighter f-stops, or use lower ISO’s. Very useful. You get shots you would otherwise lose.

After learning all this, my strategy was to use fast lenses when possible, let the ISO run wild, and count on Photolab. I should also add that IBIS is very helpful when you need a high shutter speed to slow something down so your photo isn’t blurry.

This works pretty well most of the time, but there are some issues with it. For one thing, using a lot of noise reduction on photos of people can produce creepy results that look like plastic dolls. It doesn’t seem to be as much of a problem with other creatures, perhaps because it’s easier for us to spot abnormalities in people. For another thing, if you let your ISO soar, the bright areas in your shots will often go completely white, and your software will never be able to restore the details. You lose dynamic range.

Lately, I have been listening to a guy who has a different approach: shooting for editing. It means you forget all about trying to make your images look good at the start; instead, you try to gather as much data as you need to get the best final product.

There is a lot of web photography advice that is useless for people who edit. Most advice is aimed at people who buy expensive gear and then shoot JPG’s because they are too lazy to learn to edit. A JPG can’t be manipulated nearly as much as a raw photo because in making a JPG, a camera throws out a lot of information. Many people are fine with this. They just want images that look good on a tiny phone. Also, some people have legitimate reasons for preferring JPG’s. But if you’re serious about quality and getting the most from priceless, once-in-a-lifetime shots, you want raw and editing software.

At first, shot raw because I made so many mistakes, I needed raw and editing to save me. That is still true, but later I also wanted raw because it gave me broad creative control I could never get from JPG. Now I want it because it can prevent noise from existing and save my highlights (the brighter parts of my photos).

According to the guy I learned it from, when you shoot to edit, you don’t just shoot raw; you deliberately underexpose. This prevents you from blowing out your highlights. It also makes your dark areas too dark. That’s fine, because raw images contain enough information to let you brighten your images on your desktop with little or no harm.

You shoot a dark image. You open it in a program. You brighten it to taste. Then you apply your other changes. The theory is that you will save your highlights and also get less noise than your camera’s relatively primitive amplifier would create.

I tried this yesterday with my OM1II. I set it at ISO 200 (the base) and ISO 3200, and I took shots in poor light. Believe it or not, 3200 was, for me, a new, low value. I had been shooting with a limit of 12800.

The ISO 200 shots brightened up with no noise that I could see. The 3200 shots needed noise reduction, but they worked. I think the 200 shots have some little artifacts, however, so I am thinking of going to 400 to see if the camera can do better at preventing them.

There is a problem with this approach. You may not be able to see your images on your camera’s screen or on your PC. You may get row after row of black rectangles you have to light up later. This makes it hard to review and cull. But you may be able to force your camera to create bright preview JPG’s to help you. Every raw file also contains a little JPG; when you look at the back of your camera, this is what you see. You will also see it in PC-based viewers unless you tell them to show you raw files.

Another problem: editing programs may limit how much you can increase exposure. I tried Lightroom and Photolab, and I found that Photolab would not brighten my shots enough. It turns out this is just how the programs were written. Adobe’s exposure slider goes to 11. The solution, I am told, is to use Photolab’s slider and then mask the photo and brighten the mask a little. I haven’t tried it yet. I would rather not go back and forth between programs over and over, brightening and editing. It would be great to get it all done in Photolab. It would also be great to be able to use Lightroom by itself in spite of its weak denoising. Different tools for different photos.

I haven’t tried the shoot-to-edit approach with high dynamic range yet, but it has to work, simply because it does away with overexposed highlights.

So now, once again, I know everything there is to know about exposure. What a comfort. I wonder how long it will last.