View Full Version : vertical banding issue with NN5 shot at 105mm
07-19-2009, 12:18 PM
I've been trying to get this pano' for over three weeks now driving up into Canyonlands N.P every night. So last night when I thought I'd got something interesting I was excited to put it together on the computer. Unfortunately there is a series of grey vertical shadows running down the left side of the image and I don't know why.
I shot the image on a NN5 with the RD16 rotator set to 10 degrees. There is probably about a quarter overlap, I don't know if I have too little overlap.
The image was shot with a Canon 5DMKII with a 24-105mm lens set at 105mm. The camera was set on the upper rail to 64mm as recommended on the NN site. I've tried to stitching this in Photoshop CS4 and Ptgui to the same effect.
The camera was set to manual focus and all exposures were identical.
I would have thought that if my problem were caused by insufficient overlap then I would see this vertical shadowing throughout the image and not just on one side.
One other thing
I've just remembered that might be worth noting. I forgot to remove my polariser, maybe this could be to blame.
I would very much appreciate some feedback on this.
Many thanks Andrew Waddington
07-19-2009, 10:26 PM
That is a nice scene, I can imagine why you shot the pano.
Did you already used the devignetting option in PTGui (Pro) ?
If not you should give it a try (see Exposure/HDR tab).
You could also try to reduce the banding problem in combination with the options for optimizing exposure and flare, you find the options when using the Settings button.
If generating a new curve don't give the expected result then try to use a default curve.
07-19-2009, 11:32 PM
In PTGui's Panorama Editor window, you normally see a blended version of the panorama preview. If you click the Edit Individual Images button, the unblended (but exposure adjusted) individual images will be displayed, and the brightness differences at the overlaps will be much more evident. The Pro version can do a good job of correcting the vignetting. When the joins are invisible in the unblended preview, the blended output should be perfect. Photoshop has a vignetting correction option in the RAW converter and also in Filter->:biggrin:istort->Lens Correction.
07-20-2009, 07:22 AM
A polarizing filter would cause banding very similar to this and not recommended for shooting panoramas of this sort. I for one had to learn this the hard way. The filter changes the contrast as you rotate across the sky in relationship the to position of the sun so each image is not the same.
07-20-2009, 08:09 AM
Thank you for your comments, Wim that's very nice of you to compliment my picture. I do feel Bill is probably right in saying my problem is caused by the polariser. Would you get vignetting at 105mm?
I do have Photomatix Pro and whilst I'm on my vacation it's very difficult to work on my laptop on a file as big as this, even on low res' Jpeg my computer crashed last night. Low res on a 5dmkii is still around a meg a file and with 4 rows of 10 images in this image it's thirsty stuff.
I'm in the process of uploading all 40 files to a friend back home who has a much more powerful computer and who can hopefully pull this one together. I've looked at a few images of the sky HDR'd and it looks fantastic.
Thanks again and Bill I'll be sure never to use the polariser in pano's.
07-20-2009, 08:34 AM
I have a Canon 28-105mm lens and it suffers from vignetting in all zoom settings.
As far as I know most zoom lenses will have the same behavior, perhaps your lens less then mine but for sure there will be some vignetting and for sure it will pay off to reduce/remove it.
I think a lot of the uneven brightness/contrast caused by the polarizing filter can be enhanced when using PTGui Pro's Exposure / HDR correction (if you have the standard version it is possible to buy an upgrade for the Pro version, you will not regret it).
07-20-2009, 09:41 AM
do you know about DxO Modules and DxO Optics Pro Elite. These two can help you to take away vignetting distortion etc for your camera lens combination. But you have to get the elite version for your camera. I have this software since two weeks and i like it....
Installation is a bit "crazy", takes some time and after the software is installed, you have to install the popping up "security software" as well which is not mentioned in the installing guide. This takes a fingerprint of your computer settings and saves it to the program against software piracy.
You can test a trial version, www.DxO.com and look for the modules list as well on this side.
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