Hmmm

We have a Sigma 8 and Canon 350d.  Camera controls are similar.

There should be an AF auto focus switch on the side of the lens.  "Turn it off"   

Dial your lens focus ring to where the index mark | is at infinity oxo mark. Cellotape the focus ring to the lens housing so it will not accidently move off mark. 

Turn your mode dial [round flat thumb wheel showing P Tv Av M and A-Dep] around to Av. 

Insert your compact flash card.  Turn your camera ON 

Rotate the Main Dial [near the shutter release button to set the f/stop to read 8.0

The "sweet spot for Max depth of field" for the Sigma 8 is F/8.  All between 4" in front of the lens to infinity is in focus.  Using the mode Av means your aperture or lens opening is fixed to f/8.  This will allow your shutter speed to vary to obtain a optimum exposure.  This will be true under most lighting conditions.  You might have to approach your photo session differently if you have extreme lighting  like bright sun coming through window and dark room shadows.

Mount your camera on your panorama head in the portrait orientation.  Image long side will be UP.   The Sigma 8 is a full circle fisheye image over the top of a rectangle shaped sensor.  In portrait orientation the left and right side of your image circle will be cropped because the full circle picture information does not fit entirely INSIDE the rectangle sensor.  Your crop factor is 1.6  This type of image is called DRUM type in Panoweaver.

Take 4 images around on the horizon.

When using Panoweaver load your 4 images, select DRUM 4

The rest of the process you probably already know about.

Dave,

Do you think the sweet spot for the Sigma 8mm 3.5 EX DG is also an f/stop of 8.0?

Thanks,

Robert

Yes,  we have both Sigma 8mm f4.0 and f3.5

You can test the setting by taking a series of images.

Set your tripod and camera up facing a wall with lots of detail.  Check to see the focus index mark is at  infinity oxo.

I used a brick wall. 

Also set your resolution to a medium small jpg image.. you will want to see all these side by side.  After taking about 3 or 4 images at different f/stop values load them into your favorite photo editor view them at 100%. 

Use mode Av with Variable shutter speed and 1 image at

f3.5 if you can,  f4.0, f8,  f11, f22

You would think that at f11 and 22 you would get a sharper image because its a smaller diaphram hole.  For us we picked f8 as the sharpest image.

This is not something we just learned... someone actually wrote a technical paper about it.  Ill check with a friend of mine in the UK.. he showed me the URL.

Thatone1785,

You can... I and my UK friend tested the Tokina 10 -17 mm @10mm and found that f/11 is this lens sweet spot for best depth of field between 10" in front of the lens to infinity.  

If you use M manual,  fix the aperture to f/11 and then dial in the exposure slider to the center mark on the Exposure level indicator scale, effectively you are doing the same thing as Av does it automatically. You are doing it manually.  Key is for the Tokina you need to maintain the f/11 aperture setting.  The Sigma 8 f/3.5 and 4.0 of course is f/8.

HDR - One added benifit of performing this task Manually is that if you wish to perfect your HDR technique you can of course shoot -2 stops under, 0 normal, and +2 stops over.  Then must add to your workflow time and technique for merging those under/on/over exposed into 1 single image to achieve high dynamic range image (now do that 4 times).   Which is what we did on this project using Photomatix.

Images 1 through 4 are HDR and we got a very dynamic tonal range. (#5 pole shot and 6 we done with the normal 4 images around horizon workflow).

http://360texas.com/services/sr/sttsouthlake/index.htm

1) http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

2) http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

3) http://fvlmedia.dk/tokina107/

Number 3 Flemming Larsen [noted panorama photographer] discusses specifically your Tokina Lens.  It has a small discussion and a panorama

I understand about the realestate need for faster workfow. Maybe you should limit your HDR content on $500,000+ properties.  I do not know any automatic batch that produces consistant results from image series taken under variable lighting conditions.

After several trial tests with this workflow I decided that the hospital project would be a good to actually do HDR.  Glad it turned out as well as it did.  Needless to say we do not do real estate.  As far as HDR, "getting it to look natural" is important and from my 1 project experience.. requires a lot of hands on work.

You obviously are familiar with the typical work flow.  Here is our HDR

RAW CR2's 4 click stops -2,0,+2 each stop

Photoshop CS3
Convert Adobe Camera Raw batch each 3 image series sets
correct for common white balance say daylight 5200k, chromatic abberation LENS Tab Sigma 8 CA -44,+13 Vignetting+100+12 .  Increase sharpening from +25 ->+65.

Repeat wash and rinse using same WB 5200 for next 3 sets of 3 images.  Saving ALL out as 16bit TIFFS ( click stop 1 2,3,4 12 images)

Photomatix

HDR tab Load each set of 3 TIFS from .  Genenerate 1 HDR,  apply tone map transition using default settings.  Save as 16bit hdr to single TIF file.

Repeat wash and rinse balance of the image sets.

Stitch 4 hdr TIF's to 16 bit panorama

Do very minor touchup work in Photoshop. We applied some brightening and and decreased the H&S to give them a neutral appearance. Usually NO sharpening is required.

The only reason we do not do HDR in panoweaver is because it does not let me remove the lens chromatic abberations.  CA removal is what helps bring out the sharpness in the individual images.

More information about the Tokina RAW conversion

CA means chromatic or color abberations.

Using Adobe Camera Raw converter

Sharpening TAB

Reduce the value from 25 to 0  no sharpening ( after CA correction change it from 0 back to 25%)

LENS Tab

Images contain 3 layers Red, Green, Blue.  These are called RGB channels.  Because of the lens optics... often the red channel in the RGB stack is off set by one or two pixels.  This causes the image to be slightly blurry.. or not as sharp as it could be.  So we must move the red channel layer back in line with the other 2 channel layers. 

Find a good light/dark high contrast area in the picture.  For example near the image edge a tree branch against a cloudy whitish sky.  Zoom into 400%.   Here you should begin to see the red fringe edge area of the tree branch.  Adjusting the R/G slider.. you are moving the red channel layer from side to side. 

You can actually see the red fringe slide across under the branch and reappear on the opposite side.  The idea is to CENTER the red channel so that minimum about of red fring appears on either side of the branch.

Press the ALT key to see the actual color shifts while moving the slider bar.

Do the same for  Blue / Yellow slider bar 

Rodrigo, a friend of mine.. says his Tokina uses these starting setting.

Red / Green value to -18
Blue/ Yellow value to +18

And if you only have the top image selected... click the [Select ALL] button and syncronize the other 3 images.

You will need to do a bit of experimenting with images take with your specific Tokina lens.

I will say this now... NOT all areas of the image are correctable..  adjust for 1 area should be enough to fix CA

Next return to the Sharpening Tab and reset it back to 25.

For the Sigma 8 f/4 and f/3.5 your r/g should be near -44 and b/y +13