Noisy photos - A reoccuring issue

I forgot to say that noisy problems comes more with zoom or telephoto lenses, but primes always great, but it is not a reason.

It's nice to see that the OP has it sorted now, but I'm confused...

I looked at the EXIF data from the "extreme noise" photo. It all seems pretty innocuous: focal length 42mm, manual exposure, 4secs at f/11, no exposure compensation. I'd expect that to work fine. So was the noise purely an artefact of inappropriate conversion from RAW to JPEG? In other words, if the OP had shot a JPEG to start with, would it have looked OK?

Yes, and yes.

Well then, it obviously isn't the camera then, right
Try and disable any 'auto' settings on converting, or try Canons EOS Viewer Utility or DPP, since they use the camera settings as 'default' for conversion. I've never understood why ACR uses 'auto-everything' as default. One of the first things I disabled. About as usefull as 'auto-levels': Crap.

in fact i am not aware of most processing softwares as PS but i try to do everything manually rather than Auto'ing things. but i think i have problems to adjust setting of my camera everytime i shoot.
so tell me: what settings you do with your camera rather than shutter speed and Aperature and ISO?

The OP's problem wasn't with the camera, but with the conversion from CR2 file to tiff file. So my comments have nothing to do with camera settings, but with software settings.
I shoot RAW mostly, so adjust parameters afterward if needed. In-camera parameters:

Parameters Settings
-Tone Curve Standard
-Sharpness 0
-Contrast -1

Color Matrix
-6CM set1
-Color Space Adobe RGB
-Color saturation Mid. low
-Color tone 0

I have found that in lower-light and night shots the "auto" settings try to make the scene look like daylight. When I'm converting I normally try to put things pretty close to my shot settings then work from there.

It looks a lot like noise when you over compensate the exposure, kinda like when you push the brightness up too far. Check it out.

The noise was due to ACR adjusting the exposure automatically and giving it +1.25 or more causing the noise pattern to become extremely visible. When I double checked and saw that ACR was adjusting my exposure I went and reset all my photos to 0 and the noise went away.

René Damkot wrote:
Well then, it obviously isn't the camera then, right
Try and disable any 'auto' settings on converting, or try Canons EOS Viewer Utility or DPP, since they use the camera settings as 'default' for conversion. I've never understood why ACR uses 'auto-everything' as default. One of the first things I disabled. About as usefull as 'auto-levels': Crap.

How did you disable ACR from applying "auto" settings on the RAW files?

In ACR; next to the drop down menu 'Camera RAW defaults' there is an 'arrow'. Click it and select save settings. (Untick all 'auto' fields first)
Robert Lay (don't know the exact user name) posted a pdf tutorial on POTN somewhere. Find it and read it. Very helpfull.

Thanks. That's very helpful.

What ISO do you use with your XT? I have informally checked mine and find that I start running into too much noise above the 400 ISO setting.

I use the 300D, but I try to leave it in ISO 100 as often as possible. If I don't have much light, up to ISO 200, or MAYBE 400. I rarely use 400 or above just because of the noise issue. That is one reason I would really like to upgrade. I am nowhere close to being able to afford it, but would love to get crisp pictures at ISO 1600-3200.

I agree completely. Too much noise at the higher ISO levels is a bummer.

You should try film sometimes