I was put in the situation where I had to go to the extreme with my Panasonic GX7 when I had to photography my cousins 18th birthday party last week. So, my cousin asked me to do her a favor to take pictures at the birthday party and I agreed to do that mainly because I wanted to try to see how I could handle shooting an even and consider a possibility of trying it more in the future. I was a test of my, current level of, skills (I didn't take any courses or lessons or school of art or photography, everything I learned by experience of trial and error and study from Internet and Forums) for taking photographs. All I had for this event are Panasonic GX7 (with 2 batteries), Sigma 19mm f 2.8 and Sigma 60mm f 2.8. No flash, besides the built in one, slow lenses for this kind of light. I knew the conditions would be very hard, with a lot of limitations. The dance floor had a very high ceiling so I couldn't bounce the build in flash. I used very little flash, mostly for the poses with family and friends. So it was down to very high ISO to keep a decent shutter speed. I mostly used the 60mm f 2.8 because it gave me the distance not to be intrusive (when I used the 19mm f 2.8 I was getting a bit too close for my comfort and I would get easily noticed). I did feel that it was a bit too long and wished it was closer to 82mm or 90mm. A zoom would have been even better so I could adapt the framing and the composition faster for a better story telling image, as I learned when I shot my first wedding (non-professional, second photographer) a month ago. The biggest problem, or the second but more on that a bit later, was that I needed at least 1/100 sec shutter to keep the subject motion out of the images and with the level of light I had to work with pushed me to ISO 6400 constantly, sometimes the shutter would go slower because of the light changes from the Disco Lights. Worse still, after the cake has arrived the lights were completely killed off and only the Disco Lights were running. In those conditions, the ISO went to 12.800 and underexpose the images about 2/3rds to one stop to keep a decent shutter speed. The worst problem that I was facing was the AF speed and lock on. At first, the AF was okay and it got 99% of the shots. After the lights starting going out the AF started to struggle, a lot, sometimes refusing to lock on anything, sometimes focusing on what I didn't want to (in the foreground or background). I used Face Detect and Continous Autofocus the first part of the evening because it found the faces exactly where I needed them to be without problems. When the lights went out I changed to Central AF Point and Single Autofocus because the Face Detect was having troubles. I couldn't turn on the AF Assist Lamp because it died on me 3 days before the event. I knew it was going to be hard to photograph this event so I worked around the limitations, and used High Burst and started shooting as many frames as I can get to try and get as many as I could. I expected to throw away many of them, and I did, out of 4.200 images (insane, I know) I came out with about 600 usable. At ISO 12.800 I had to give up on looking for critical sharpness or even decent, I just went with what is in focus, doesn't have too much subject motion blur and tells the story that I want to represent (like people having fun and enjoying themselves). In the end, I used 3 batteries (recharged the one of them while I was shooting the second one) and filled up 64 GB of storage. And besides the frustrations of the limitations of light and gear and skills (I do acknowledge that I have a lot to learn) I liked doing it and it helped my fear/intimidations of taking candid pictures of people (I'm not much of a street photographer or a social person). Also for this kind of job I need a dedicated Flash, faster lens (f 1.8 would have helped keep the ISO lower but f 1.4/1.2 lenses are not cheap, 1600$ is a lot for example). Better AF in low light is very essential. Maybe people that own the newer models of Olympus/Panasonic can tell me if AF is better on things like E-M1 or GH4 or EM5 II. I would like to post some of my favorites samples of that event. I did edit them to best of my abilities, I prefer a bit more noise then no details (a trait I learned to live with and appreciate sometimes from my Panasonic G1/G2 old days), and I downsampled them to 5 MP so the noise wouldn't be so noticeable (most people down own a screen bigger than 2560 pixels across this days). PS. Sorry for the long read. Even with the build in flash fired the ISO was high and because of the long distance that Sigma 60mm f 2.8 gave me so I can include more people in shot it's power was diminishing fast. I love this image a lot because of her smile and expression. Actually, I have a lot more pictures of her looking every adorable that evening. It was very important that I would get moments such as this captured because it's what most people remember from those kinds of nights. Candid shots are not easy to take but worth the effort. The most memorable moments of the evening are what clients want. It is better to have a noisy image than no image at all. Hard to sell a client this kind of quality but luckily it wasn't a paid gig and it made me understand the need for adeqate gear.