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I'm a novice photographer with a 450D/XSi. I'm using a 50mm/1.8 prime lens to start out and I noticed that a lot of times my pictures end up not being sharp for stationary scenes. I was mostly using manual focus and switched to using auto focus mainly for this reason. The problem is even with auto focus this happens.
I noticed this mostly happens when a subject is from around 5 - 10 m, and in low light situations. I try to keep the aperture at around f/2.8 to get better sharpness without opening it all the way. I increase the ISO to get better exposure (even though my camera's high ISOs are not that good). But, I do decrease my shutter to around 1/25 s. The image shown is an example of this. The settings are f/2.8, 400 ISO, 1/25s.
I think the lower shutter speed may contribute to this focus problem, but I'm not sure whether it's the only reason. Is the focal length of the lens also a contributing factor here? But, most online material doesn't say anything about focal length when giving recommendations for landscapes (I assume that if it's good enough for objects at infinity, then it should be good enough for objects at 10m). So, I assume this is not the case. Is that right? Is it possible to get some recommendations as to what sort of settings I should aim for to get the best focus given I have a good exposure given I have an objects at 5m - 10m?