Wild PhotoMag: The Wonder of Mirror-Up for Low Light Photos

Article and photos by Denni Raubenheimer
***Click on images for high res versions

All experienced photographers with long lenses can attest to the challenges that low light brings to achieving sharp images. One of the fundamental things that I teach beginner clients with regards to shutter speed is how to know if your shutter speed is quick enough to avoid camera shake when shooting hand-held. The guide line is simple: keep your shutter speed faster than your focal length, or at least equal to it, when shooting hand-held. If your camera has a cropped sensor then I advocate using your effective focal length as the minimum. However, this isn’t always feasible in low light. This is where Mirror-Up shutter release mode, or a delayed shutter, becomes useful.


Leopard at sunset. Focal length 420mm without VR at 1/400s using a bean bag with Mirror-Up. Click on image for high res version.

Professional Nikon D-SLRs have a shutter release mode called Mirror-Up (M-Up). This mode is the same as activating Mirror Lock-Up with a Canon, or other D-SLR, but it is readily accessible. It is also effectively the same as setting a delay of at least one second between your camera’s mirror-lift and the actuation of the shutter.

Mirror-Up isn’t always the go-to in low light situations, one will usually compensate for low light with large apertures, high ISOs, physical stabilization (e.g. a bean bag) and, or vibration reduction (i.e. image stabilization). However, for relatively stationary subjects and especially when you want to avoid excessive ISOs and don’t have very good image stabilization (or none at all) Mirror-Up can help you produce sharp images at shutter speeds well below those you would usually require.

Reflections and ripples in water at sunset. Focal length 420mm without VR and on a beanbag at 1/320s with Mirror-Up.

In Mirror-Up one needs to press the shutter button twice to take a photo. The first press lifts the camera’s mirror, the second one releases the shutter. If one waits a second or two after the mirror lifts, before pressing the shutter button a second time the vibrations caused by the mirror lifting will have largely faded and will not reduce image sharpness. The effect of these vibrations are negligible at high shutter speeds, but at low shutter speeds they will reduce image sharpness. Obviously, their effect become redundant if the camera is not kept physically stable – then blurring caused by the “macro” movements of the camera will far outweigh blurring caused by the internal vibrations produced by mirror-lift. Furthermore, different D-SLR camera models’ mirrors produce different amounts of vibration as their sizes, weights and rotational velocities differ. Nevertheless, at shutter speeds that are low relative to focal length when one’s camera is kept relatively static, avoiding the vibrations generated by mirror-lift will always improve image sharpness.

The Nikon D800 has a 36MP full-frame sensor that can show very high levels of detail and thus easily betrays a lack of sharpness. It’s mirror-lift (or rather -slap) causes significant vibrations and when using good quality lenses vibrations coming from the mirror can significantly impact image sharpness at slow shutter speeds. With the D800 I most often shoot wildlife at 420 mm (300mm f/4 with 1.4 TC) with a Nikkor lens that does not have VR (i.e. IS). Due to the high resolution that the combination of the lens and sensor give, the photos quickly betray lacking sharpness. Personally, I find that for consistently pin-sharp images (when not panning) with this combo hand-held I need to go faster than 1/800s (i.e. 1/1000s, or faster). In low-light I have found that if I have to shoot hand-held at 420mm I can use 1/400s when I use Mirror-Up and get consistently acceptable sharpness, and noticeable sharper images than when not using Mirror-Up. I would then estimate one stop improved stability for hand-held without VR (i.e. IS) at telephoto focal lengths.

Burchell's zebra at sunset. Focal length 420mm without VR and hand held at 1/320s with Mirror-Up.

Where the release mode really shines is when I use it on a beanbag. When shooting wildlife from a vehicle and to a lesser extent on foot I am very fond of bean bags. The are not as stable as tripods, but give lots of maneuverability with lenses that are not excessive in weight. With the non-VR 300mm f/4 + 1.4 TC and on a steady beanbag I can quite comfortably shoot at 1/250s and expect sharp images (without a cable release), whereas I would not try and avoid going below 1/400s in these conditions in regular release modes (remember the D800 easily betrays lacking sharpness and has significant “mirror-slap”). When I need to, I can go even slower on a bean bag with Mirror-Up. The below image of the Giraffe was taken at 420mm and 1/100s on a not-so steady bean bag.

Giraffe at sunset. Focal length 420mm without VR and using bean bag at 1/100s with Mirror-Up.

100% crop of above image.

I once was forced to capture bioluminescent waves under a starry sky on a beanbag (I cannot remember if it was with, or without a cable release). I only had a brief few moments to grab equipment before my “body guards” left for the beach and had decided not to add a tripod to our flight luggage. Furthermore, my “guards” quickly became impatient on the beach, so I just went for Mirror-Up and tried keeping the camera as static a possible on the beanbag (mounted on a laundry basket!). In the end I used 1s exposures at ISO-12800. Amazingly, a portion of the images were acceptably sharp!

Bioluminescent ocean waves under starry sky. Focal length 24mm on bean bag at 1s shutter speed with Mirror-Up.

The draw-back for using Mirror-Up on live subjects and when shooting without a tripod is that after lifting the mirror you shoot blind, i.e. your view-finder is completely black. Also, you obviously lose continuous release. However, in situations where my subject does not require continuous release and the light demands slower shutter speeds than the value of my focal length Mirror-Up is often part of the solution – and sometimes invaluable.