Help on Panorama

[CraigVTR]

High guys. Shot this last November when I was in Katoomba and have just found some time to play around with it. After stitching in Panorama Factory there is this strange colour shift through the image. It seems to be in the raw files so I would think I need to do a colour balance across all the images before I do the stitch job, but I am wondering what caused it. The camera was set to auto white balance, I used a grad nd filter and I may have used a polariser. Me thinks the wb and the polariser may be the problem. Any suggestions welcome.

[Bob G]

Craig -

I am no expert on panoramas but certainly the Auto WB is a potential problem but you should be able to match the Colour temp. on the individual Raw Images in Capture or Photoshop before you merge them.

The polariser however is a bigger problem and you would need to do some serious PP work in the merged photo on the sky in particular to overcome this

[dm_td5]

stubbsy made a comment a CPL in a Pano thread of mine. I hadn't actually considered the effect a polarizing filter would have, thinking it simply work in with the picture as you expect for a single shot. I'm curious about this and I suspect that if it is the CPL causing the issue then it will be cyclicle in the pano and occur at a repeating number of degrees within the camera rotation.

[Oneputt]

I totally agree that this was caused by the CPL. In doing an HDR you need to remove the variables so that the merging images are as close as possible to having the same characteristics. This is almost impossible with the use of a CPL.

[Joshman]

ok, let's ask the simple question first, are all your shots exposed the same? same shutter speed? aperture? ISO? if they are constant through out your panorama images, then i would have to agree with it possibly being the CPL.

as for the CPL affecting a HDR picture, i would disagree, as the only variable in exposing for HDR bracketing is (should be) your shutter speed. everything else is a constant.

[Mr Darcy]

I disagree that the CPL is causing this. A polariser would not be a good idea, but the colour shift would be different.

See link for a single shot using a CPL on a 10mm lens. You can clearly see the colour change in the sky. FWIW the photo was taken about 5km from yours, but approx Due North where yours was taken approx due South. Imagine your panorama as a slice through the middle.
Warning. It is a very large image.
http://www.swtd.com.au/images/GJK/UltraWideSunAtSide.JPG
As you can see the colour shift is of quite a different nature to that shown in your image.

I suspect the AutoWB was at fault. As suggested earlier, try setting the WB of all your RAW images to the same K value, and try again.