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My High ISO Secret

The Craft of Clean
by Mark Ritson Juni 17 2018
 

A good few people have asked me how I am getting clean sharp images from high ISO files, “what is your secret, you must be doing something”, even if levelled as a sort of an accusation, I’m flattered.

It is fair to say that in part, the answer is perception, the trick is to enhance the perception of sharpness and low noise. The techniques I use create a result greater than the sum of the parts. All the images presented here were taken between ISO 3200 and ISO 5000, and the Kingfisher and Osprey between ISO 1000 and 1600. This is high even with modern cameras and especially so with my crop sensors. It is certainly high enough to impact the overall image quality in a negative way. I’d be delighted if I could stay below ISO 800 when shooting wildlife.

Jay, ISO 5000

Kingfisher, ISO 1250

I have previously talked about my Benro Mach 3 tripod being the ultimate noise reduction system due to enabling a lower ISO to be set (which will often mean a slow shutter speed), allowing both sharp and noise free images to be captured even in strong winds, such is the stability offered by this brilliant tripod. Of course, this is only perfect if the subject is still, such as a mountain or building, or indeed with desired motion blur from water and clouds. But what about a squirrel? A Jay? A Woodpecker? A Sparrowhawk? Then it becomes a little tricky, even when perched on a post, seemingly still or feeding wildlife is making constant erratic and fast movements of the head, as they continually monitor the safety of their position. If there is one thing wildlife is perpetually concerned with, it is avoiding becoming lunch!

I was in Scotland recently and had the good fortune to see wild Red Squirrel, Jay, Greater Spotted Woodpecker and Sparrowhawk, but alas it was raining, the light was very low, and the subjects were, as ever, twitchy. What to do?

Red Squirrel, ISO 3200

First, and regardless of the tripod and gimbal being in use I needed a fast-enough shutter speed to ensure a sharp image of these twitchy subjects, but this, of course, forces the ISO up, creating unwanted noise. I do not know that my approach to the problem is the best, but it is my theory that the most crucial factor in creating a great image in these circumstances, accepting that shutter speed needs to be high enough to freeze the subject, is exposure, exposure, exposure. Absolute nailed, correct exposure.

One massive caveat here, what is correct exposure? Quite simply the one that gives the look you want! The point is to nail exposure in camera and not while editing, why? Because the one slider in post I do not want to touch (when the ISO is high) is the exposure slider. I know! I know!

Expose to the right as noise should not be exacerbated when taking exposure down is, of course, an accepted mantra, but this does not help with blown white feathers or fur, hence I have an alternative approach. With high ISO images, I find even minor adjustments using the exposure slider very quickly crumbles the image into a mess of noise and this applies to raw files too, I find that the images can look like they are made of shortbread biscuit crumbs! Don’t forget I am strictly talking about the exposure that gives me the look I want, not the exposure that attempts to render 18% grey. My goal is to avoid moving the exposure slider in post, which in turn gives me the best chance of dealing with noise in post without losing detail or sharpness, which is key in wildlife images since I want to reveal as much as possible the glorious detail and texture in our wildlife. Sharpness is also perceptive and this technique of nailing the exposure to provide me with the look I want helps greatly with perceptive sharpness as I can retain more detail and texture.

Male Sparrowhawk, ISO 3200

So, to determine “my” correct exposure, I start by using my Sekonic light meter (yes 18% grey) and ideally will aim the spot meter at a white feather or white fur or maybe light green foliage. Of course, if a Red Squirrel walks by giving a baby elephant a piggyback while a robin sits nearby juggling balls I’m dropping the light meter and firing shots. But in planning, on arrival, where possible I’m taking readings and firing shots using those readings as a start point. I will then make minor adjustments, monitoring the results until I have the detail and look that I want, which may be quite different from the original meter reading or technically correct exposure, but will be close enough to render detail in the dominant feather or fur colour while giving me my desired look.

A case in point is the white face of the woodpecker below, really good detail here could easily be lost if using the exposure to the right regardless method. Keep in mind, my objective is to avoid adjusting exposure in post. In a scene with plenty of good light, I will not be so twitchy about exposure, I can rely on the camera to meter confident that a well saturated raw image has latitude. But a raw file in bad light and high ISO does not have this luxury, especially with a crop sensor, and there are many reasons I use crop sensor cameras for wildlife. Technology is brilliant, but we can ask too much.

Greater Spotted Woodpecker and Lashing Rain, ISO 3200

Once I have determined the correct exposure for the look I want I will then decide how to achieve that same exposure with the fastest shutter speed. I will increase the shutter speed and open the aperture to achieve the same value and look of the desired exposure, but aperture can only go so wide. F2.8 or f4 might be typical for wildlife prime lenses (or higher with big zooms) but I may need greater depth of field and as such, I am restricted on how much I can open the aperture and thereafter the ISO must go up. So, I want a shutter speed that is just fast enough for a sharp image and accepts the ISO that this dictates, but I will try to keep it on the edge of just fast enough in order to moderate the ISO, it isn’t camera movement that I’m concerned with, remember it is the subject movement in this instance that I am trying to freeze. In the cases of the images here, shutter speeds were around 1/640th and one was 1/1000th but with a 600mm lens, this is on the edge because the tiniest micro-movements with that focal length can be dramatically disappointing.

The use of my Benro Mach 3 and Gimbal assists greatly with this stability issue and with that of more considered framing. Another great advantage of having the camera and lens rig on my Benro Mach 3 and Gimbal is not having to bear the weight of the gear myself all day long! This gives me hands-free use of the considerable time between action for further exposure checks with my light meter and compositional changes along with the odd coffee.

Kingfisher, ISO 1600

These images were shot over a single session of 13 hours, I would not have handheld for this duration. My exercise with exposure will continue throughout the day as both the light and my desired intention changes. I think this process has been important in helping me take control of the image I want to create, I want to be certain of the look and feel of what I am creating rather than what the camera created, especially so with high ISO files because they are rarely flexible in post.

Once I have my images loaded into my computer for editing I will hopefully make zero adjustments to exposure, instead, I will concentrate on my holy trinity of perceptive sharpness which is detail, tone and contrast. I say the holy trinity with the condition that my exposure needs no adjustment. Together this holy trinity (plus one) gives me the results I intend. I find the features in Skylum Luminar 2018 to be excellent, especially the tone filters. I use Skylum Luminar as a plugin to Lightroom. Once I’m satisfied with this aspect of the edit, I will then pay attention to saturation and vibrancy as high ISO depletes colours and of course raw files are flat, to begin with. I’m now ready to apply noise reduction, using masking in order ensure as much detail as possible is retained in the subject.

My method is not as easy as “expose to the right”, but if it really was that easy, all images would be just as we wanted, and our main concern would be finding wall space for the final print. But it isn’t like that, it is effort and intent that is rewarded in photography.

Male Sparrowhawk, ISO 3200


All images shot with Micro Four Thirds and APS-C crop sensor cameras.



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