Originally posted by safc I don't no much about flashers what's the difference you said manual only
That you really have to think about configuring the flash before taking a shot, each and every time. It's not that complicated; read the K-r manual (section about flash) for the relationship between guide number, aperture and subject distance. It might even become second nature.
But I would suggest a flash that has at least an automatic mode (where the flash will do measurements to determine correct exposure and not likely overexpose). Can't advise on any as I haven't looked at flashes for ages so I don't know what is available in your price range.
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ttl means 'through the lens'; the camera will determine correct exposure and tell the flash to stop emitting light when correct exposure is 'expected'. It's basically the above mentioned auto mode, but done by the camera.
With p-ttl the camera instructs the flash to emit light (the pre-flash) so the camera can do some calculations. This happens before the actual image is taken.