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Pentax K-7 vs Canon 50D vs Nikon D90?
This is what you do. Instead of having a lot of people give opinions that may or may not have anything to do with real world of photography, do this Go to a camera store and see which camera fits your hands best. See what menu is the easiest cameras so you can use to make changes in ISO, resolution of the camera, white balance, change mode and make changes EV. Finally, take an SD card with you and test each camera on its highest and lowest ISO as well as when using the white balance to match the light in the store, as well as her the white car "balance" mode. Once you get home and are able to see the results in large computer monitor, you'll know which camera is best for you, not us
Pentax K20D Video Overview