Hi CDG,  welcome to the forum

hmm  yes I can see the noise.

Noise is a function of the sensor.  The lower ISO the better.  The Canon 5d has an ISO 50.

Sigma 8mm f/3.5 recommend f/8  and Av aperature priority let the shutter speed determine the proper exposure.   OR.. use f/8 and average the metering shutter speeds at the 4 click stop locations.. then enter the average shutter speed  value in manual mode.

You can also try auto exposure value bracketing (AEB) say.. EV -2,0,+2 then use some software like Panoweaver 5 or HDRsoft Photomatix.  That might remove some of the noise presents.

IF you shoot RAW, I think Photoshop CS3  Adobe Camera Raw 4.4.1 converter has some color noise reduction functions.  AND you can also remove the Sigma 8mm chromatic abberation.  digital images are red/green blue.  The red layer sometimes is off set by 1 or 2 pixels.  Adjusting the red layer so that ALL RGB pixels line up properly makes the image sharper.

Noiseninja removes excessive noise.

Morning CDG and Pixelator

Things to avoid

floor, ceiling and wall tile

standing in the center of rooms or staircases - shoot offset 

mirrors

bright windows

ANYthing moving

If I can think of anything else.. I will return.

Quote: Originally posted by CDG2008 on June-18-2008

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If you have small rooms, such as a bathroom, do you still do a tour on that?

Thanks in advance.

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Quote: Originally posted by CDG2008 on June-18-2008

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I agree that I need to try either bracketing or the higher shutter speed.

Thanks in advance.

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Question was Why offset room setup?

Avoid room center
1. Typically an item of interest like chandelier or room fan is in center of room and all you would see is up view of the object.
2. Other objects are in room floor center requiring time to relocate.
3.  I have had poor stitching results in the zenith area with out taking a 5th UP view.
4.  Without a tape measure, you probably won't shoot exact room center anyway.

Off set benefits,
1. Imaging will include full height of chandelier or room fan.  Turn room fan ON  to show fan blade desireable movement blur.  Helps avoid trying to stitch static multiple fan blades together.
2.   When we shoot, we try to keep at least a 3 foot [1 meter] clear zone around the tripod feet. Creates a clear walk space during camera rotation.   For us, we usually find clear space zones in about the 1/3 - 2/3rd area of the room.   This comes from people living space.  Furniture [couches and chairs] usually is along the room walls.
3. Object stitiching issues usually occur in the bottom 20% of the image top and bottom.  Maintaining the 3 foot [1 meter] tripod clear space assures object stitching issues reduction.
4. Square room center setup the room ceiling height will be somewhat equal heights around the image horizon.  Symetrically room setup is ok for special effects. 
5. Offset room setup creates a visual variation in wall /ceilings heights and captures the occasional chandelier/ room fan as well as an opportunity to view through an open door way into the adjacent room.