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Panorama exposure blending
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I was trying out a few Multi shot panoramas on hols, but I was shooting Ap priority. As a result there are differences in exps. I shot in raw so I can compensate. Do you know is there any way of matching the exposures, apart from just adjusting by sight? I use CS4.
Cheers, Ger.I think you need to watch your white balance, I am nearly sure I read somewhere that
you should use manual white balance settings for panoramas?? Could be totally wrong of
course :lol: Shooting raw will help as you have more control over the finished look.OK, I’d suggest you take a look at the shutter speed of each shot. Take the centre image as the key image.
Then using that you can calculate how many stops up or down the exposure is for each image from your key image by the difference in shutter speed. The apperture should be the same if you’re in Aperture Priority. Use the raw converter to under or over expose the images around the key image so the are all exposed the same simulated shutter speed. Oh, and if you were on auto-iso, you can do something similar.
You may have a further problem, in that if your white balance was set to Auto, as it may shift from one image to the other. In this case, use your raw converter to ensure the colour temperature and tint are the same for all the images.
Cheers,
Dave.Chart by Craig Cooper that might help:
http://photo.net/casual-conversations-forum/00Kp9Aand a more comprehensive chart here:
http://www.fredparker.com/ultexp1.htm#EXPOSURE%20FACTOR%20RELATIONSHIP%20CHART%20BOh, one more thing. When you adjust your exposure/colour temp etc in camera raw, it stores this information in a sidecar .XMP file when you click on “Done” in camera raw. You can then go into Photoshop (if that’s what you’re using to stitch), select the menuoption to photomerge, and select your raw files, and photoshop will automatically pick up the exposure info from the associated .XMP files, and use the adjusted raw files for the merge. Saves you having to save out to TIFF or PSD first.
Rgds,
Dave.Thanks for the input, Dave. Sometimes it needs some one else to point out the obvious solution !
As mentioned by MMX use manual mode on your camera and this will prevent the “stripe” effect on
your source images. As with most things better to get it right in camera first. Before taking any images
do a test pan through your scene checking the exposures as you go. Take an average of these exposures
and use that in your manual settings. All your exposures should be the same then.
Hope this helps.
Martinmartinkingphotos wrote:
Take an average of these exposures and use that in your manual settings.
It´s not that simple, first of all you must be sure that no part of the panorama will be blown out, if some areas are underexposed you simply correct them later, with digital cameras it´s much easier to correct underexposed than overexposed areas.
actually i find it easier to fix over than under, the same method guy gowan uses, as when things are under by fixing you add a lot of noise
and most modern cameras are at least 14bit, so have loads of headroom over the histogram
stcstc wrote:
actually i find it easier to fix over than under
Yes and no :)
Yes, it is good to overexpose the shot a bit, so when you later darken it, it will reduce noise. It´s called “expose (to the) right” technique. HOWEVER; overexposed doesn´t mean blown-out. Once the area is white, there´s no way how to fix it. And with digital sensors (as well as with positive films), you are much more likely to get white areas than black areas.
With negative films it´s exactly the opposite way – you can easily get 100% black but you rarely get 100% white.I don´t know what Guy Gowan uses, but this is determined by the technology itself, it´s not about one´s preference.
http://en.wikipedia.org/wiki/Exposure_(photography” onclick=”window.open(this.href);return false;)Yea, I agree if it’s clipped it’s gone. But for example my 40d I have a good stop and a half past the end of the histogram. So I very rarely clip the highlights but intentionally overexpose them all the time
I have been using Auto Pano Giga and getting banding in my final stitches, but discovered it was me.
Now to get successful stitching I use:
No Auto Exposure, No Auto ISO, No AWB.
Hope this helps.
Regards,
Niall
MMX wrote:
stcstc wrote:
actually i find it easier to fix over than under
I don´t know what Guy Gowan uses, but this is determined by the technology itself, it´s not about one´s preference.
http://en.wikipedia.org/wiki/Exposure_(photography” onclick=”window.open(this.href);return false;)It not actually what he “uses”, what stcstc is referring to isnt actually exposing to the right, that’s “correct exposure function”
what he’s referring to is the fact that the dynamic range of most digital sensors is larger than most people think and as such you can expose beyond the right and retrieve the data in ACR (or any other raw converter) by up to 1.5 stops
what I do (and I have about 10,000 of them….) when constructing a panorama is do a sweep to find the brightest part of the shot, overexpose by 1.5 stops if outdoors, or if indoors spot meter the section of the brightest frame I want correct exposure in (you can’t always avoid highlight blowout indoors with windows) and overexpose by 1.5, then bring it back by 1.5 in ACR, which pushes a whole lot more data down into the left of the histogram where the fewest levels are available for detail and use shadow/highlight to extract some extra detail…
next invest in a dedicated pan stitching program (not expensive I use panorama factory) which will have exposure blending so no stripes!!
the last one I did is not printed and hung 3metres x 15metres
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