I spent two days photographing the IDEA Personal Trainer Institute in Alexandria, VA. I really enjoy shooting this event, but the lighting in the hotel meeting rooms is horrible. Some of the the sessions are presentations, but most of the sessions involve a large amount of movement and activity with trainers jumping, running, stretching, etc.
So here you are with poorly lit rooms and the need to stop action. I get about 10 to 20 minutes per session and I have to move onto the next session. There is no time to setup lighting, and in most cases there is no room to setup lighting and you can't risk a trainer tripping over a light stand. About half the time I use my on camera flash with a CTO filter and bounce some light off the ceiling and walls to up the lighting about a stop in the room. Most of the time I am shooting at ISO 3200 when I am using a flash in this manner, and if I don't use a flash I am between ISO 3200 and 12,800.
I brought four cameras: the Nikon D4, Nikon D3S, Nikon D800E, and the Olympus OM-D E-M5. The D4 and D3S are the BEST low light camera on the planet and are my go to cameras to capture action in low light. I have three prime lenses, the 24mm F1.4, the 50mm F1.4, and the 85mm F1.4. I also use three zoom lenses, the 14-24mm F2.8, the 24-70mm F2.8, and the 70-200mm F2.8. I wasn't sure how I would use the D800E. It has too many megapixels for what the client needs. I take a few thousand photographs over these two days and I don't need a ton of 36MB files to process.
I found myself using the Nikon D800E in DX crop mode with the Nikon 85mm F1.4 lens. This gave me an effective 127mm lens at F1.4. The D800E is about one stop less sensitive than the D3S or D4. After a couple of days with a couple of heavy cameras around my neck, the D800E with an 85mm is a lot lighter than the D4 with my 70-200. And the big benefits is that the DX RAW files are only 16mb vs 36mb. The other thing I love about this combination is that the 51 focus points cover the entire frame. I tend to put a focus point right on my subject's eye and this gives me the ability to frame my subject how I want and still have a focus point over the the eye.
I also brought my Olympus OM-D EM-5 camera with three lenses: the Olympus 14 F2.5 pancake lens, the Panasonic 25mm F1.4 lens, and the Panasonic 100MM - 300MM lens. I tried to use the Olympus for some of the low light, action situations but it wasn't up to it. Because of the action I need great auto focus, though the Olympus is good, it can't focus like the Nikons when it comes to action photography. I also need to be comfortable taking photos with an ISO of 3200 plus. The Olympus is a good two stops worse in low light than the Nikons. I did find one thing that the Olympus did that the Nikons couldn't, I put the 100-300 on my Olympus which gave me an effective 200mm to 600mm range. I found that the rooms in which there were just presentations were better lit, and little action (primarily just a speaker, and the attendees sitting at a table). I could pull out my Olympus with my effective 600MM lens I could get so close shooting from afar. The other thing that was surprising is that when you marry the image stabilization of the Panasonic 100-300mm lens with the built-in images stabilization of the Olympus OM-D you can hand hold a 600mm lens at 1/125 with no problem.
Here is a sample photo shot with my Olympus OM-D, 600mm, ISO 6400, 1/125, F5.6 - not bad considering:
I tried to take some action shots with the Olympus at ISO 6400 with no flash. It was slightly underexposed and I got a very noisy image.
As expected, the Nikon D3S (and D4) were amazing in low light. The next image was shot at 1/250, with a Nikon 24mm F1.4 at F1.8 using ISO 6400, very clean!
The next image was shot with a Nkon D4 at 1/250, with a Nikon 24-70mm F2.8 at F2.8 using ISO 9,000, very impressive!
And here is the Nikon D800E with my Nikon 85MM F1.4 shot at ISO 4000, F2.0, 1/320. I shoot the Nikon D800E in DX crop mode, making my D800E about at 16MB camera vs the mega 36MB native full frame FX format. It gives me better reach and a more usable file size. Not as clean at the Nikon D4 or D3S, it is about a stop worse in terms of noise.