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550D blurry/unsharp pictures after use on telescope. caused by dew?


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I'm a bit unsure of the reason, but for some reason my 550D suddenly seems rather blurry/unsharp at 100% crop for daytime pictures. The sensor is clean of any dust.

I've changed my noise and sharpness settings without luck, and i always shoot in raw as the JPG converter on the 550D is just as good as a fish is able to climb trees...

I've thought maybe it was my focusing that was off, so i tried manual focus, still no change. Tried on a tripid and mirror lockup, still no change. Thought maybe it was my UV filter causing it, took it off, no change.

Thought maybe it simply was the lens that just wasn't really sharp, but after trying with several lenses, i get same unsharp image from all of them. Tried EF50 1.4@5.6. EF-s 18-200 @6,3, different focal lenghts. Even the EF-s 10-22 stepped down was unsharp.

So now i'm a bit confused. seeing other pics from 550D, and seeing some of my first 550D pictures, i can see it's obviously sharper.

Only thing i know i haven't tried is re-cleaning the sensor.

It was cleaned not so long ago, and is dust free. But i know that since last cleaning, i've used it outside in the cold, and also on my explorer 200 scope. I'm not 100% sure, but about 80% sure that the sensor hyave dewed up several times since last cleaning.

Is it possible that repetadly dewing of the sensor can cause images to be a bit soft/unshart at 100% crop - without any signs of dust on teh sensor?

Anyone else have similar experience?

I'd normally just clean it and see - but unfortunately i'm out of sensor swabs, and they're rather expencive too so i won't be able to clean it for a while... :(

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Any sample images. I doubt it's dust on the sensor. I take dust on my CCD sensors as a fact of life, they don't cause blurring. Has the camera had any sort of know to that might put the lens mounting out of true?

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It's not sensor dust. I Have some spots here and there as it's not possible to not have any dust at all, but that's not a problem. The problem is that at 100% crop, it's overall less sharp and detailed then what i remember it used to be.

I can try to take some sample pictures later today.

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  • 2 weeks later...

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