Dealing with very poor lighting (and very high ISO)

Singapore zoo runs nightly shows that are mainly a bit of marketing for the zoo and the environment - but you get to see a serval, a blond raccoon, some impressive birds of prey, snakes, a very smart otter and a hyena.
This shot was relatively easy to get as the man was standing under a spotlight (so much for not blinding the nocturnal animals).
Canon full frame EOS5D MkIII, 300mm focal length lens, f4 @ 1/125s,  ISO6400 (This pic by Natalie Hitchens.
All other images by Robin Nichols)

One of the (many) attractions in Singapore is to visit the night zoo. As the name suggests, you go there after dark which enables you to see a range of shy, nocturnal and semi-nocturnal critters that you'd never see in regular zoo times. If you are hoping to photograph some of the more interesting inhabitants you have to resort to using both a long telephoto lens and a very high ISO setting. These two factors present two very tricky problems for any photographer. To get an acceptable framing of, say a hyena, across the small paddock, you need a 200mm lens at least. On a regular APS-C sensor camera (i.e. most DSLRs) this means you might need a shutter speed of 1/200s, or higher, to avoid camera shake, tricky when the entire forest floor seems only to be illuminated by one or two high up (and weak) floodlights.

The beautiful Serval made an appearance in the spotlight but as you can see on the left, it was sort of daylight-balanced in the foreground but red in the background (the people who design these shows never consider photographers!).
Plus it appeared behind a fence.
I retouched the wire out using the Healing Brush in Photoshop CC, then corrected the White Balance with the Colour Balance feature, reduced the colour noise by 50% and added about 25% sharpening to get the cleaner looking result on the RHS.
Canon EOS 5D MkIII, 300mm 1/60s @ f4, ISO 6400

Hyenas look weird in good light so imagine how creepy this was under weak floodlights. Because I was using a 1.4 Extender I was losing one f-stop of light to get the extra magnification. To get more light, I increased the ISO to the maximum on my Canon (ISO25,600), shot at 3f2.8 with a shutter speed of 1/25s and manual focus - and amazingly go this sharp result.
Post production involved NO sharpening (as this only makes the noise worse) but adding:
maximum Luminance noise removal
max Detail, max Contrast, 50% Colour Noise removal plus max Detail and max Softness using Lightroom's Detail panel (noise reduction) sliders.
I also retouched the wires out and added a strong colour correction using the Colour Balance feature.
(Note the saliva drool).

In fact, in most of the exhibits the light levels are so low that you have to stand for a few minutes before you can see anything, let alone the animal in the enclosure. Obviously flash is not allowed because you are likely to blind the animal, and get barred by the zoo so you have to hoist the ISO to compensate. From ISO 6400 to begin with, up to 25,000 in some places because the light is so low. Shooting at these massive settings brings a new set of problems: digital noise. I use Canon which seem to have the worst colour noise characteristics of any camera so, in post, it is necessary to crank up both the Luminance and the Colour Noise removal sliders. Here's what I came up with - not the best set of animal shots but considering the lack of light, something at least...

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Greater mouse deer relaxing in leaf litter.
A mouse deer is neither mouse, nor deer. They are, in general almost impossible to see on account of their nocturnal habits, tiny size and ability to blend into the forest floor almost perfectly.
This female is about the size of a large domestic cat
Canon EOS 5D MkIII, 200mm lens, 1/25s @ f2.8, 10,000 ISO + noise reduction

Indian Barking Deer
This guy was altogether better illuminated allowing me to bring the ISO back down to 6400 and still capture a steady shot in the gloomy forest floor.

Top: Probably the hardest to shoot was this serval. Its enclosure was almost totally dark to my eyes so I had to shoot wide open at f2.8 with a slow shutter speed of 1/13s at ISO 25,600 and hope for the best with manual focussing.
Bottom: The result was gloomy and very noisy so it required a lot of work just to get it looking half decent.
Adjusted the brightness + noise reduction.
As with the other night photos I didn't bother adding any sharpening because this really accentuates the already poor noise characteristics.

This is what Lightroom's Detail pane looks like when I correct the noise in a very high ISO (6400++) image.
No sharpening will help produce less noise - and a cleaner looking final result.

This owl was shot using manual focus (because I could hardly see the owl, let alone if it was in focus).
1/25s @ f2.8,, through glass, at ISO 20,000 - the resulting image is quite soft but still acceptable considering the extreme shooting conditions...