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Author Topic: Tilt Shift and Panoramas  (Read 29436 times)
fike
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« on: March 26, 2010, 04:16:27 PM »
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I am considering adding a tilt shift lens to my repertoire.  I have been reading about them and they sound ideal for the type of work I like to do--environmental panoramics in the forest with lots of complex foreground and soaring vertical lines with lots of crisp focus.  That's what I like.

I am considering the Canon 17 mm F/4 L Tilt Shift.

The tutorials at http://www.cambridgeincolour.com/tutorials.htm have helped me understand tilt shift lenses better, but I have some questions.

Here is how I am considering using it.
1) I intend to mount my camera in the portrait position on a pano head (I think I may not really need the yaw control as much any more if I am content with the shift giving me enough additional vertical coverage).

2) I was going to make shift panos (left and right) without moving the rotating platform, basically three frames overlapping a bit in the middle frame to make smallish (roughly square) panos.  

3) I figured I could use the pano head to spin the camera around the nodal point (do they work the same on tilt shift lenses?) and stitch two or more of these shifted panos together to make a larger panoramic image.  

4) So far I have only used the shift mechanism to capture a wider field of view.  I guess I could add-in the tilt to improve depth of field for my wilderness scene, from foreground to the horizon (speaking theoretically, here).  

So presuming that everything I said above is generally practical and sensible, here are some questions:
If I am making a pano in the portrait orientation (as usual) and I use the shift mechanism vertically, to increase the pixels in the Y axis (with effectively 2.5 rows of photos), would I need to modify the tilt between the bottom row shift and the middle row and top row shift? I can imagine some pretty weird results in the foreground where the depth of field would be shallowest.

How would using a spherical panoramic head and moving the tilt shift camera in the pitch rotation change the behavior of the tilt shift lens?  All the tutorials discuss generally use of the lens with the camera mounted level (for instructional purposes, I understand why they do this.)  I can't even begin to imagine the possibilities of angling the focal plane while tilting the camera. The geometry is simple, but the practical application (if there is one) seems more complex.
« Last Edit: March 26, 2010, 04:17:46 PM by fike » Logged

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« Reply #1 on: March 26, 2010, 04:20:37 PM »
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I believe the physics questions implied might very well cause some heads to explode
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elf
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« Reply #2 on: March 26, 2010, 11:10:55 PM »
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Quote from: fike
I am considering adding a tilt shift lens to my repertoire.  I have been reading about them and they sound ideal for the type of work I like to do--environmental panoramics in the forest with lots of complex foreground and soaring vertical lines with lots of crisp focus.  That's what I like.

I am considering the Canon 17 mm F/4 L Tilt Shift.

The tutorials at http://www.cambridgeincolour.com/tutorials.htm have helped me understand tilt shift lenses better, but I have some questions.

Here is how I am considering using it.
1) I intend to mount my camera in the portrait position on a pano head (I think I may not really need the yaw control as much any more if I am content with the shift giving me enough additional vertical coverage).

2) I was going to make shift panos (left and right) without moving the rotating platform, basically three frames overlapping a bit in the middle frame to make smallish (roughly square) panos.  

3) I figured I could use the pano head to spin the camera around the nodal point (do they work the same on tilt shift lenses?) and stitch two or more of these shifted panos together to make a larger panoramic image.  

4) So far I have only used the shift mechanism to capture a wider field of view.  I guess I could add-in the tilt to improve depth of field for my wilderness scene, from foreground to the horizon (speaking theoretically, here).  

So presuming that everything I said above is generally practical and sensible, here are some questions:
If I am making a pano in the portrait orientation (as usual) and I use the shift mechanism vertically, to increase the pixels in the Y axis (with effectively 2.5 rows of photos), would I need to modify the tilt between the bottom row shift and the middle row and top row shift? I can imagine some pretty weird results in the foreground where the depth of field would be shallowest.

How would using a spherical panoramic head and moving the tilt shift camera in the pitch rotation change the behavior of the tilt shift lens?  All the tutorials discuss generally use of the lens with the camera mounted level (for instructional purposes, I understand why they do this.)  I can't even begin to imagine the possibilities of angling the focal plane while tilting the camera. The geometry is simple, but the practical application (if there is one) seems more complex.

Shifting using a T/S lens is rather pointless on a properly adjusted spherical pano head. That said, it can be done. You will need to shift the camera body the opposite direction of the lens shift in order to keep the entrance pupil in the same location to eliminate parallax errors.

Tilting is a lot more interesting, but will be very time consuming since you will need to reset it for each frame.  With practice you may be able to shoot a pano in a reasonable amount of time.

The tilt will affect the whole image circle, so if you combine a tilt with a shift, you'll need to check the critical focus over the entire image circle.  In other words you'll need to set the tilt, shift max up, adjust tilt, shift max down, adjust tilt, shift right, adjust tilt, shift left, adjust tilt and repeat until focus is correct for the entire image circle (or at least the part that you'll be using)


The tilt is the relationship between the lens and the sensor.  How the camera/lens combination is oriented is not relevant.  What will change dramatically is where the focus plane is located relative to the subject when the pano head is rotated.
« Last Edit: March 26, 2010, 11:12:53 PM by elf » Logged
JeffKohn
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« Reply #3 on: March 27, 2010, 01:32:34 AM »
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Keep in mind a 17mm lens is awfully wide for stitching unless you're using a cropped-sensor camera. Like, freakishly wide, getting into the range where a rectilinear projection just doesn't look good at all.

Even on a cropped sensor camera, I think the 24mm would be a lot more useful for stitching, regardless of whether you're using shift or a rotating pano head. I used the 24 PC-E quite a bit for stitching when I was shooting cropped-format. Now on full-frame it's really wider than I would want to use for stitching in most cases.

Disregard the above if you're wanting to do those 360-VR spherical panos for the web (but you don't want a shift-lens for those, you want a fisheye).


One more thing about stitching: either use shift, or rotate the camera; but don't do both. As elf said it just doesn't really make sense to do both. In fact my experience is that you get worse results than if you hadn't shifted.

There are times when it makes sense to use tilts when doing a rotational pano, but at 17mm you should have plenty of DOF, I doubt you're going to need tilts in most situations.
« Last Edit: March 27, 2010, 01:34:23 AM by JeffKohn » Logged

Dick Roadnight
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« Reply #4 on: March 27, 2010, 02:18:00 AM »
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For single row rectilinear, side-shift and stitch is better than pan-and-stitch (no distortion, no cropping off corners).

With a very short lens, you have so much depth of field, you would not need tilt to get it all in focus.

I had contemplated using tilt on the foreground of a typical "beech and cliff" (or lawn and house, church yard and church, carpet and wall...) picture, for single vertical row shift and stitch, to get the foreground in focus (the hope is that the tilt only affects the focus, so aligning the two shots requires no distortion)... I do not know if or how pano-stitching software would cope with combining these vertical rows horizontally for a multi-row shot.

For cylinder stitching, longer lenses work better.

What exactly are you contemplating doing, on what type of scene?
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« Reply #5 on: March 27, 2010, 05:45:11 AM »
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Here's a shot I made with the TS-E 17 in landscape orientation, shifting up and down to make 3 photos.  There is almost no distortion with this lens, so shifting the lens instead of the sensor didn't really have any negative impact.

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Dick Roadnight
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« Reply #6 on: March 27, 2010, 06:00:00 AM »
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Quote from: RazorTM
Here's a shot I made with the TS-E 17 in landscape orientation, shifting up and down to make 3 photos.  There is almost no distortion with this lens, so shifting the lens instead of the sensor didn't really have any negative impact.
...and you had stacks of DOF without tilting?,,, or could you, or did you, use tilt for the bottom picture to get the foreground in focus?
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« Reply #7 on: March 27, 2010, 09:52:26 AM »
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Quote from: Dick Roadnight
...and you had stacks of DOF without tilting?,,, or could you, or did you, use tilt for the bottom picture to get the foreground in focus?

I used tilt and infinity focus to get all of the water in focus, but I left the tilt and focus alone when I shifted for the top and bottom photos.  When you shift up 12mm, the area in focus is shifting up 12mm as well, which is practically unnoticeable.
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Dick Roadnight
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« Reply #8 on: March 27, 2010, 10:55:50 AM »
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Quote from: RazorTM
I used tilt and infinity focus to get all of the water in focus, but I left the tilt and focus alone when I shifted for the top and bottom photos.  When you shift up 12mm, the area in focus is shifting up 12mm as well, which is practically unnoticeable.
Leaving the tilt setting saves any possible problems,,, but what about a floor/wall ceiling or three walls shot? Cylinder or sphere panos should be able to cope, but, if the original images are OOF, they the software could not fix it.
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elf
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« Reply #9 on: March 27, 2010, 06:31:25 PM »
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Quote from: RazorTM
Here's a shot I made with the TS-E 17 in landscape orientation, shifting up and down to make 3 photos.  There is almost no distortion with this lens, so shifting the lens instead of the sensor didn't really have any negative impact.


This type of scene lends itself well to T/S.  I don't think it will work as well with a typical forest scene where you want to get foreground objects  as well the trees in focus.  My first attempt using a T/S lens on a scene where trees were reflecting on a river was a complete bust.  The desired plane of focus was really a reversed L so it was not possible to have it all in focus at once.  

Tilt was set on the center image in this one, then both horizontal and vertical shifts were used.


I think if you analyze your images carefully you can tell whether or not a T/S lens will be usefull to you.  If you can get everything into a single plane of focus, the T/S lens will work very well for you.  If not, I would look at focus stacking software like Zerene Stacker or TuFuse.
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« Reply #10 on: March 28, 2010, 09:45:12 AM »
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Interesting comments and responses.  Thanks!

I am planning on using a cropped sensor camera for my work.  So, it would behave  something more like a 28mm lens.  It is an interesting thought to try the 24mm version. The 24mm is a little cheaper and a little faster.  One reason that I was considering the 17mm is that I typically walk-around with a 24-105 and I like to conserve resources.  If I can add a new focal length to my quiver of lenses while adding tilt shift, that would be ideal.  Adding a 24mm TS would be great, but slightly redundant.  

I plan on using this for woodland scenes and stands of trees.  I really like the effect of perfectly focused foreground along with perfectly focused trees shooting up in front of me.  Someone mentioned the woodland scene having a an arrangement more like an "L-shape" than a plane. I need to think about that.

As for the suitability of panoramic rotation with a TS lens:  I can see that pitch rotation (using a spherical head) would be impractical if you were planning on shifting up and down on a camera mounted in the portrait orientation.  But if I do that, wouldn't I need to pivot the camera to move left and right.  It seems to me that without moving the camera, you can shift your way into making a "plus-sign" shaped image where the corners that would be needed to make a square image would be left out.  I am basing this on the fact that you can only shift in one direction at a time.  Is that correct for the cannon lenses?

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« Reply #11 on: March 28, 2010, 12:18:33 PM »
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The 1.4x teleconverter on the 17mm also looks like a pretty decent way to increase its flexibility.
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« Reply #12 on: March 28, 2010, 01:15:59 PM »
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Quote from: fike
The 1.4x teleconverter on the 17mm also looks like a pretty decent way to increase its flexibility.


NO, dont do that if you care about image quality.

Works sort of ok with the 24TS II but not with the 17 at all.

TES
« Last Edit: March 28, 2010, 01:19:28 PM by tesfoto » Logged
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« Reply #13 on: March 29, 2010, 08:34:24 AM »
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So my research has continued to progress.  It seems that most of the responses here are discussing making shift panos while the film plane remains in a fixed position.  As I understand it, this technique can generate a roughly square mosaic, and it DOES indeed appear that mixing in a tilt with this approach would be complicated and difficult (there better not be clouds in the sky because by the time I am done messing with the lens, they will move).

The approach I am considering is kind of a hybrid between panoramic stitching and shift stitching, and I am not sure if my reasoning is flawed.  Let me try to explain my idea.

Let's say I am photographing a wall with framed art on it, and the floor in front of it that has a beautiful persian rug with fine detail.  I want the rug and the framed art to be in perfect focus.  I can make all sorts of compromises with higher apertures (don't get into focus stacking, it isn't always practical), but with a tilt shift lens, I should be able to get both in focus by making two images and merging them in post processing.  

First, I would shift the camera down to take the lower half of the scene, including the floor with the carpet on it.  I would tilt the lens to draw the focal plane inward towards the camera, rendering the floor in perfect focus.  I would take the first image.

Second, I would reset the tilt to zero and then shift the lens upward, focus on the framed art and take the top half of the scene.  

These two images would have different focus planes, but they would intersect at the base of the wall.  I would then use photoshop to merge the two images at the base of the wall.

Now, what if pivoted the camera around the entrance pupil (nodal point) and completed the same procedure to the left and to the right of the original shifted panoramic.  I would have 2 rows of 3 images.  I could stitch the lower row and the upper row separately, and then stitch them together.  I realize that this procedure couldn't cover a very wide angle because as the camera pivots, the focal plane would move too much, but otherwise, it seems like it might work (I realize that this might not work well with the 17mm, so perhaps the 24mm is preferable).

Do I understand the tilt shift lens capabilities correctly? Am I crazy?
« Last Edit: March 29, 2010, 08:36:08 AM by fike » Logged

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« Reply #14 on: March 29, 2010, 12:06:47 PM »
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Quote from: fike
First, I would shift the camera down to take the lower half of the scene, including the floor with the carpet on it.  I would tilt the lens to draw the focal plane inward towards the camera, rendering the floor in perfect focus.  I would take the first image.

Second, I would reset the tilt to zero and then shift the lens upward, focus on the framed art and take the top half of the scene.  

These two images would have different focus planes, but they would intersect at the base of the wall.  I would then use photoshop to merge the two images at the base of the wall.
I think that would work...

The effective focus distance would be different, so you would have to scale to get the two exposures lined up... but that would be child's play in this example, as you can cut off at a straight line at the bottom of the wall.

It might be more complicated if there was furniture in the shot.
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« Reply #15 on: March 29, 2010, 06:32:19 PM »
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With the panoramic capabilities offered by digital stitchers, and for the kind of scenes you are interested in (nature landscapes), I think using a regular lens with proper panorama stitching would be cheaper and could even produce better results.

Stitching images from a TS lens is very easy and will preserve the rectilinear projection of the lens. This is good, and even necessary, for arquitecture and rectilinear subjects in general.

But for nature subjects such as trees, yo could be more interested in a non-rectilinear projection that keeps the trees vertical, but compresses their rectilinear thickness in both extremes. With a rectilinear projection, if the angle of view is wide trees on the right and on the left will display much thicker than the trees in the middle, right in front of you. This distortion is easily minimised by using some other kind of projection (see a lot of them here: PTAssembler Projections). And if any non-rectilinear projection is desired for your application, a TS lens doesn't make much sense because it will not save you the time and effort it would with rectilinear projections in mind.

Regards
« Last Edit: March 29, 2010, 09:46:16 PM by Guillermo Luijk » Logged

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« Reply #16 on: March 29, 2010, 08:57:21 PM »
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When you tilt, the entrance pupil (some call it the nodal point) is going to move both horizontally and vertically, so if you want a parallax free stitch you'll need some method of moving the entrance pupil back to the horizontal and vertical pivot points of the spherical pano head.  My setup allows this, but in practice I found that it was just too much of a headache to move it the precise amount required.

I would suggest that you shouldn't try to force fit a T/S lens into your current style of shooting, but should explore how to exploit the strengths of the T/S lens and see where it takes you.  I took a brief tour through your site and I didn't see any images that could have been taken with a T/S lens using tilts.
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« Reply #17 on: March 30, 2010, 07:11:54 AM »
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Quote from: elf
When you tilt, the entrance pupil (some call it the nodal point) is going to move both horizontally and vertically, so if you want a parallax free stitch you'll need some method of moving the entrance pupil back to the horizontal and vertical pivot points of the spherical pano head.  My setup allows this, but in practice I found that it was just too much of a headache to move it the precise amount required.

I would suggest that you shouldn't try to force fit a T/S lens into your current style of shooting, but should explore how to exploit the strengths of the T/S lens and see where it takes you.  I took a brief tour through your site and I didn't see any images that could have been taken with a T/S lens using tilts.

That's some of the specific feedback I was hoping for.  So you say that the entrance pupil moves with a tilt.  Does it also move with a shift?  Entrance pupil calibration of a T/S lens would be a PITA.

My thought on the use of shifts in my style is that I could tilt the bottom of the focal plane slightly in towards the camera to give the perception of a slightly greater depth of field from foreground to tree trunks through the woodland shots that I like so much.  perhaps a shot like this could benefit from a tilt, http://marcshaffer.net/fine-art-panoramics...land-creek.html or this one, http://marcshaffer.net/fine-art-panoramics...mmer-creek.html .

As for force fitting T/S into my panoramic style, you may be right that I am coming at T/S from a particular viewpoint.  It seems to me that using a T/S with panoramic techniques would require a substantial simplification of the shooting methods to avoid going nuts with fine, detailed adjustments, as you mentioned.
« Last Edit: March 30, 2010, 07:14:02 AM by fike » Logged

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« Reply #18 on: March 30, 2010, 12:26:33 PM »
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Quote from: fike
That's some of the specific feedback I was hoping for.  So you say that the entrance pupil moves with a tilt.  Does it also move with a shift?  Entrance pupil calibration of a T/S lens would be a PITA.

My thought on the use of shifts in my style is that I could tilt the bottom of the focal plane slightly in towards the camera to give the perception of a slightly greater depth of field from foreground to tree trunks through the woodland shots that I like so much.  perhaps a shot like this could benefit from a tilt, http://marcshaffer.net/fine-art-panoramics...land-creek.html or this one, http://marcshaffer.net/fine-art-panoramics...mmer-creek.html .

As for force fitting T/S into my panoramic style, you may be right that I am coming at T/S from a particular viewpoint.  It seems to me that using a T/S with panoramic techniques would require a substantial simplification of the shooting methods to avoid going nuts with fine, detailed adjustments, as you mentioned.

Those two could easily be taken with T/S, but I'm not sure you would gain much from what you have already. I think focus stacking would probably be easier and quicker for subjects that are static.  

I have a Hartblei 80mm Superrotator, and shifting and tilting moves the entrance pupil.  The entrance pupil just moves the amount of the shift, but tilts are moving it at an angle.  The precision that you rotate around the entrance pupil determines how much parallax you'll have. Most landscape images can tolerate quite a bit of parallax error if you want to spend the time in PP blending the seams.  Most of the stitching software can handle handheld shots, so it may not be as big a deal as it sounds.  My setup, http://luminous-landscape.com/forum/index....rical+pano+head , has the camera mounted on an L bracket to allow moving it horizontally and vertically to correct for shifts and tilts.  I also added stops for maximum shifts so I could do it quickly.  After I did that, I realized I had half of a view camera, so I added the bellows and front movements.  With Nikon lens, it will focus on infinity.  In practice, the T/S lens is quite a bit slower to set up for each frame than just using the pano head to rotate.  I'm sure people that have used LF cameras with movements will be able to set up and shoot quite a bit quicker and are probably quite puzzled about why I'm saying it's so tedious to do   Checking the focus accuracy on a DSLR is very hard to do compared to an LF.  My camera has 10X liveview, but can't scroll the view without exiting the 10X mode. Going through the process of adding a tilt, verifying the focus at the corners, and repeating until the focus is perfect is a very time consuming task with a DSLR.

I should add that there is probably nothing more fun in photography than manipulating the focus plane.  It justifies the expense.  I wouild recommend looking at the new Hartblei SuperRotators with the Zeiss optics.  I think they more than equal the Canon and Nikon T/S lens optically and they have a lot more functionality.

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« Reply #19 on: March 30, 2010, 03:36:11 PM »
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Quote from: elf
Those two could easily be taken with T/S, but I'm not sure you would gain much from what you have already. I think focus stacking would probably be easier and quicker for subjects that are static.

I haven't had good luck with focus stacking for woodland shots.  Light filtering through gently moving leaves is impossible to deal with for HDR and focus stacking because you are usually left with halos.

Quote from: elf
Most landscape images can tolerate quite a bit of parallax error if you want to spend the time in PP blending the seams. Most of the stitching software can handle handheld shots, so it may not be as big a deal as it sounds.  My setup, http://luminous-landscape.com/forum/index....rical+pano+head , has the camera mounted on an L bracket to allow moving it horizontally and vertically to correct for shifts and tilts.  ...

You are confirming my suspicion that the small movement of the entrance pupil in a shift or tilt will not be likely to create large problems for a cylindrical stitch, particularly where landscape scenes are concerned. Buildings and interior architecture may be a bit different.


This statement from The Digital Picture Review of 24mm T/S confused me a bit though.

[!--quoteo(post=0:date=:name=The Digital Picture)--][div class=\'quotetop\']QUOTE (The Digital Picture)[div class=\'quotemain\'][!--quotec--]Ideally, for this technique to work best, the lens position (not the camera position) should remain constant for these shots - to avoid parallax in foreground objects. There are various means of adjusting the camera the 12 degrees in both side-to-side directions (vertical is more difficult) to accomplish this, but using an Arca-Swiss compatible quick-release clamp and plate make this task relatively easy. Just measure and apply a couple of small indicators on the clamp and plate. Then move the camera the opposite direction of the shift movement - so that the lens remains in its place.[/quote]

Do people do this with an L bracket and a focusing rail turned sideways like you would for a stereo photographic setup?  I have a bunch of RRS pano head stuff, but I don't immediately have a way to move the camera vertically to accommodate vertical shifts.  Is this amount of precision needed when you can use a stitcher to clean up minor misalignments?
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