Forum : Advice & Critiques

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Topic: DIY pano head

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Memoryoke (Over 1 year ago)
Made my first DIY Panopamic head on the weekend... getting better at using it, but there are often little errors 

(see the window frame)
http://photosynth.net/view.aspx?cid=0c1a5697-8339-4966-8725-74f6f6d3fd31

or large ones 

(see the black picture on the wall)
http://photosynth.net/view.aspx?cid=efdb6392-7db3-4f2f-aa4e-067ad08cd314

Is it possible to get a perfect 360 pano with a DIY head? 

What's your secret???
Nathanael (Over 1 year ago)
Pretty cool! 

Do you have a weblog entry about your panoramic tripod head? It would be great to get a look at it and hear about the construction process.

My first question is whether your tripod head rotates the camera around the camera's lens/imaging plane or rotates around some other part of the camera. 

It might be that ICE would still make a stitching mistake with a perfect set of input photos, but the problem with traditional panorama stitching is that the stitchers don't handle parallax well, meaning that if your camera's lens is traveling in an orbit with a diameter of, say, nine inches, the difference in perspective (small though it may be) will result in foreground objects and background objects being different distances from each other in your various input photos. When the panorama stitcher attempts to align all the photos to any particular corner, this means that other portions of the photos don't line up.
Nathanael (Over 1 year ago)
Another thing to consider when trying to get a perfect panoramic stitch is that you almost certainly want to lock the camera's focus to a particular aperature and make sure that the camera will not automatically change the focus between shots. 

Perhaps you're wondering why I say this. After all, doesn't locking your camera's focus mean that some parts of the panorama will be out of focus in all your input shots? 

Think of this: even if your camera is being perfectly rotated around the point at which it stops the incoming rays of light (meaning that all objects are identical distances relative to each other in all input photos), if your camera is changing the distance that it is focusing at, it means that the edges of some objects will be thicker in some shots than in others, depending on where the camera's focus is. That just can't be perfectly automatically stitched. 

Examples: 
http://bit.ly/focusdiffblinds
http://bit.ly/focusdifftree
Nathanael (Over 1 year ago)
I'm by no means a photography expert, but I believe that the smaller your camera's aperture is, the closer you will be to "infinite focus" (meaning you will be locking out depth of field).

Depth of field isn't at all bad, though. I think that an entire panorama that has a consistent depth of field could actually be quite beautiful, so long as you have something worthy of sharp focus in the foreground on all sides. Again, the main point should only be that the depth of field be consistent in all input photos.
Nathanael (Over 1 year ago)
Tom Benedict ( http://photosynth.net/userprofilepage.aspx?user=tbenedict ) has a fascinating image up on flickr ( http://www.flickr.com/photos/tbenedict/3183443667/ ) where he used modified camera firmware and post-processing software to capture 54 images of a single photo's field of view where each input photo focuses at a slightly different distance and then the post-processing software selects and preserves the sharpest portion of each input photo to create a single photo where every part of the scene is in maximally sharp focus. 

I would love to see an entire panorama stitched where each input camera position was the result of this sort of process so that everything in sight was in perfect focus, but that would be an overwhelming amount of work, even for the average enthusiast.
Nathanael (Over 1 year ago)
If our aim is to capture both many different exposures (to generate true HDR) as well as many different focal lengths (hopefully I'm using that term correctly) the problem becomes one of multiplication. Tom's example above illustrates a bit of this. Technically, he just used 27 different focal lengths multiplied by two different exposures (the two different expsures being to generate a high dynamic range final image). 

Even if you are only capturing two different exposures, capturing all of those different focal lengths for each of the camera's many different views would be a large undertaking but I expect that in a scene with lighting that is less controlled than Tom's example you would want even more exposures and if the distance between your nearest and furthest subjects is much greater than his example, it is quite possible that you would want more than 27 increments of focal length, as well, provided your lens can deliver more.

Still I'd love to see this.
Memoryoke (Over 1 year ago)
Thanks for your thoughts Nathanael. I am no stranger to composite photographs (see my M.A. work (scroll down for the most assembled stuff)

http://www.artdoxa.com/users/Lee_Campbell/artwork_catalogs/150/artworks/large?page=1

but nowhere near as perfect as Tom. 

You spotted the use of auto focus in my living room pano! However I did use manual focus for the RoomStreet test. One problem with my DIY head is that the bracket is quite flexible, so I have to have a 10sec timer for each photograph as it wobbles to a stop. When shooting a HDR Pano this can get quite time consuming (for readers who don't know, this means each photo is taken three times: bracketing above and below).

So here is my DIY pano head!!! 
http://www.flickr.com/photos/airlock/6175830251/in/photostream/
Nathanael (Over 1 year ago)
Thanks for the look at your pano head. 

Apologies for oversimplifying the topic for you, but I generally try to write so that anyone else who reads our conversation will have a broad idea of what's going on and some vocabulary to research on their own time if they want.

I'd love to get the input of some of our panorama focused authors like Thomas Hayden in here.
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