Dumb question about my XTi -noisy pictures?

[lordfly]

Right. So yesterday I was fiddling around taking some self-portraits (I'm an ugly goober, but it was for a contest and I needed the practice anyway) with the XTi. It was a bright, sunny day here in Michigan, amplified somewhat by the snow on the ground. I had all of my curtains open, there was plenty of light in the house (or so I thought). I even had my tripod out.

Taking pictures was... interesting. According to the camera it was far too dark for 100 ISO (25 second exposures) so I had to bump it up to 400. Not out of the question, of course, most indoor photos require that anyway, right?

So after loading up the files on my computer (RAW files), I notice something; they're noisy as hell. The nominally white wall behind my ugly mug is riddled with color noise and my face is a blocky mess. This is with Raw!

What's going on here? I was under the impression that raw files were far superior as far as file quality goes. Or is there a major disadvantage in that the basic RAW format doesn't go through any processing whatsoever and thus the original images will be blocky and noisy?

Or am I just doing this all wrong (always a possibility)?

 

[Dao]

Is your photo underexposed?

 

[TiaS]

What was the ISO? If you shot in RAW and they were underexposed and you brought it up on the computer, that can also create noise.

 

[fokker]

RAW isn't any better in quality as such, it just an unmolested starting point with more potential for non-destructive editing. If that makes sense.

Also, even at 100 ISO a 25 second exposure sounds way too long, what f/ number were you using? It sounds like you've badly underexposed the image and tried to bring up the exposure from a RAW, which works well for a stop or two but you start to get a lot of noise introduced...

 

[Gaerek]

RAW isn't any better in quality as such, it just an unmolested starting point with more potential for non-destructive editing. If that makes sense.

Also, even at 100 ISO a 25 second exposure sounds way too long, what f/ number were you using? It sounds like you've badly underexposed the image and tried to bring up the exposure from a RAW, which works well for a stop or two but you start to get a lot of noise introduced...

^^^This

I have an XTi and I have never had a serious issue with noise at ISO 400. It seems like you were underexposed and were likely using a smaller aperture. Try opening up the aperture all the way and even use the exposure compensation to increase the exposure by 1/3 - 2/3 stop, just to see if that helps.

Something to keep in mind, with film, we were always told it was better to underexpose than to overexpose. With digital, it's far better to overexpose than to underexpose. Just be sure not to blow your highlights.

 

[bahandi]

Yes, what was your aperture setting?

 

[LBPhotog]

Yeah, 100 ISO and 25 second exposure sounds a touch "ODD" to me. I too would like to know the f/stop and I bet we are talking about an under exposed image ...

 

[lordfly]

Yeah, 100 ISO and 25 second exposure sounds a touch "ODD" to me. I too would like to know the f/stop and I bet we are talking about an under exposed image ...

400 ISO speed, 1/2 sec exposure at f/5.0 has the color noise.

Unfortunately I'm a dummy and deleted these RAW files last night. Give me a few minutes and I'll take some test shots against a white wall. Maybe I'm just doing it all wrong.

 

[lordfly]

Well, I guess I'm mistaken. The 100 ISO pictures I took were 10 second exposures (just a blank white wall). Close up they don't look too bad. I had a few other 100 ISO pictures that were 1/2 sec exposures. Some were too dark... gotta learn to use exposure adjustments, I guess.

And on looking at the pictures again they don't seem too bad... goodness, perhaps I should lay off the Nyquil or something. Even the 1600 speeds don't seem bad (grainy, but not with color noise).

This is a relief; I was beginning to think the XTi was a junker or something.

Thanks everyone for the tips; heading out now to enjoy this nice spring weather and take some pics at the State Park.

 

[tomhooper]

Is anyone else confused as to exactly what he shot?

 

[lordfly]

Is anyone else confused as to exactly what he shot?

Yeah, I don't explain myself very well sometimes.

I was taking self portraits by setting the camera to timed release; taking a picture of me standing in front of a white wall inside my house.

I also took a bunch of test shots for focusing and whatnot against the plain white wall; that's where I was noticing most of the noise. Upon further investigation I indeed had the settings messed up, along with other errors.

In short, disregard thread.

 

[tomhooper]

No problem, I just wanted to help if I could and didn't quite understand what you had done.