Answer to "Power on problem on 50D"First check the battery compartment door. There is a micro switch that turns the camera off when you open it. If the battery cover does not press down on the switch the camera won't go on. Make sure that the battery compartment door covers the batteries so that the micro switch senses that the cover is closed. Or you can also send your camera to repair center if it is under warranty or you implement other troubleshooting ideas from Canon 50d Manual to resolve this issue.
Answer to "won't turn on through battery grip"(1) Always check the battery first; it is the most common culprit with a dead camera. Is the battery charged? Is the battery inserted correctly? Are the battery's metal connectors clean? (If not, you can use a soft cloth to remove any grime from the connectors.) Are there any particles or foreign objects in the battery compartment that could prevent a good connection? (2) ith most Nikon point and shoot cameras, you can press a "monitor" button or a "display" button that will place the shooting settings and information on the display screen. Repeatedly pressing this button will cause different information to appear on the screen or will remove all shooting data from the screen. (3) Check more solutions from Nikon d300 Manual.
Answer to "Why is my viewfinder blurry on my Nikon D600?"ADJUST YOUR DIOPTER: Next to your viewfinder, there is small dial with a plus(+) and minus(-) sign next to it. This is called the diopter and it measures the optical power of the lens. In other words, it is almost like putting a set of glasses on your camera to sharpen what your eye sees through the lens. This will have no effect on your images (obviously, as you've noticed since your images are still turning out nice and sharp). Just simply adjust this so that what you are seeing comes into focus and you can effectively tell what is in focus and what isn't with your eye alone. This is important if you are doing any manual focus with your lens at any point. The diopter adjustments are not drastic and most likely will not replace any need you have for wearing glasses. The adjustments are just enough to increase the clarity if it seems a little soft when you look through the camera. As a little side note, if you are using someone else's camera with diopter adjustments, don't be surprised if you start to get...