Originally posted by Unsinkable II At 28mm the GR will spank a RX100. Above that (aside from the 35mm crop function on the GR), the GR is out of the game.
Well the RX-100 sensor is about 1.5 stops smaller. The DxOMark low light score shows this, with the RX-100 having a score of ISO 390 vs the K-iis score of 1208. I'm guessing the GR will have a similar performance to the K-iis. So, a 1.5 stop difference in area, yields a 1.5 stop difference in low light performance. BUT, the RX-100 lens is about 1.3 stops faster than the GR. It has a max aperture of F/1.8 vs F/2.8. So for lower light shooting, they should be pretty similar. If you have enough light to shoot the GR at ISO 100, it should reach a level of performance the RX-100 can't touch.
I own an RX-100, and I'm thinking of selling it to buy the GR. What I love about the RX-100 is is small size and versatility. I rigged up a mini-bounce card that I taped to the pop up flash. I also taped a small tab to the back of the flash so I can easily aim the flash at the ceiling and also aim my mini-bounce card to do some forward fill. It's a very effective combo and very pocketable. The 20MP sensor is really nice and the HDR modes work well. However, I kinda feel like the Sony was designed for gadget lovers and the Ricoh was designed for photographers.