Bad images for stereo pair

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soldevilla
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Location: Barcelona, more or less

Bad images for stereo pair

Post by soldevilla »

for two times the last days, I have tried to do 3 images in Zerene stacking for to do a stereo pair and I have obtained the central image perfectly focused but the first and the last image (the stereo pair) seem moved.
the images have been made ​​as always, StackShot y Zerene in mode Aling & Stack all, Pmax...

Image

rjlittlefield
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Re: Bad images for stereo pair

Post by rjlittlefield »

soldevilla wrote:for two times the last days, I have tried to do 3 images in Zerene stacking for to do a stereo pair and I have obtained the central image perfectly focused but the first and the last image (the stereo pair) seem moved.
If you mean that your stack consists of only 3 images total, then Zerene Stacker's synthetic stereo is not likely to give good results. Instead it will give exactly what you're describing: the center image will appear in its normal position and the front/back images will appear shifted left and right.

To get good stereo, you typically need a minimum of roughly 20 images. More is better, but after 50 or so the improvement is marginal.

With a deeper stack, your description still holds true: the center image will appear in its normal position while the farther front/back images will appear shifted left and right, in proportion to their depth. But in this case the shift between adjacent images is much smaller so you don't perceive it as a shift.

Zerene Stacker's method works best for deep stacks at higher magnification and wider apertures, where the DOF per slice is small compared to the total depth of the subject.

With shallow stacks and a correspondingly shallow subject, it may still be possible to get a useful result, by reducing the maximum shifts at Options > Preferences > Stereo/Rocking to be a small fraction of what you would use with a deeper subject. This will greatly reduce the perception of depth, but that's consistent with having a shallow subject.

--Rik

soldevilla
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Joined: Thu Dec 16, 2010 2:49 pm
Location: Barcelona, more or less

Post by soldevilla »

Thanks Rik.

I did not explained properly (ugh, my English ...) I get 3 images, but I stack them between 30 and 60 images for each outcome.

I will continue testing and if the problem reappears I commented here with all the data, for now I am left with the idea that a larger DOF is not nice to get a stereo pair. Does that mean that too many images, too many little separation between them, not a good idea for a stereo?

thanks

rjlittlefield
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Post by rjlittlefield »

Lots of images with little separation should work fine.

Looking again at your image, I wonder if you accidentally specified a huge shift, for example +-30% instead of +-3%. That would cause a correspondingly huge shift per frame and could produce the "echo" effect I see in your second image here.

--Rik

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