What causes this?

This was taken this morning with my 17-40 and 350d is it my camera? Should it do this?

Liam: wrote in post #4540723
...Should it do this?

Should it do what? Sorry, maybe it's too early in the morning for me and my brain may not be fully awake yet, but what is the issue here?


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Not sure what your exactly trying to point out. The big red boxes? Are you sure that they weren’t in the scene?

Seriously, what are you pointing out? I can’t seem it.

I'm sorry, but I can't see anything either. Can you describe the problem please?

lol sorry,
The red boxes show were the two crops came from and you can see huge pixels, you can even see them on the 1st one if you tilt your screen.

Ok, I was kidding about the boxes, but I am still not seeing what your pointing out.

Well on the 2nd picture there are purple boxes (pixels) which you can see in the first picture. And the same with the third except yellow and orange. The sky was perfectly clear when I took the picture no clouds.

Or am I just seeing things?

Are you shooting in Small Jpeg format? If so those are Jpeg compression artifacts you are seeing.

JPEG compression artifacts? I assume this was taken from a 100% crop of a JPEG, not RAW image.

I can see it in the dark picture of the barn, but not the sky. It's like really bad compression.


Edit: Haha. Three replies within a minute all saying the same thing.

Hi Liam - I'll take your word for it, I just can't see it on my monitor. Does this show up on prints seen at normal viewing distance? Perhaps it's dust on a sensor, or bug near the lens, or bird distant in the sky? I'm stretching here......

wilvoeka wrote in post #4540816
Are you shooting in Small Jpeg format? If so those are Jpeg compression artifacts you are seeing.

No just checked; large not compressed.

sapearl wrote in post #4540835
Hi Liam - I'll take your word for it, I just can't see it on my monitor. Does this show up on prints seen at normal viewing distance? Perhaps it's dust on a sensor, or bug near the lens, or bird distant in the sky? I'm stretching here......

If you tilt your monitor up you should be able to see it.

Forgot what I said in me prior post - naryab and Birchwood are making more sense with their suggestions. I'd forgotten about THAT possibility, which makes more sense.

No birds, and yes was jpeg but hasn't been compressed is like it in the original.