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Author Topic: Photomerge shooting techniques  (Read 14402 times)

wmchauncey

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Photomerge shooting techniques
« on: February 12, 2015, 07:22:15 am »

I do a lot of floral, macro-type, photomerging photography using a video head tripod that has a center lift mechanism in the tripod.
I can't seem to get consistent results between the technique of moving the center shaft up/down or simply rotating the video
head to overlap the images the appropriate 30-40%.

I'm growing weary of manually aligning the overlap when the "merge to panorama" doesn't work in PS CC.
In an ideal scenario...what might I do differently?
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MarkL

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Re: Photomerge shooting techniques
« Reply #1 on: February 12, 2015, 08:21:22 am »

Camera postion/parallax errors show up very large at such close distances, you will likely need a proper pano setup, tilt shift lens or a technical camera.

First though, try PTgui for as your pano stitcher which you can set points in the images to stitch.
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dwswager

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Re: Photomerge shooting techniques
« Reply #2 on: February 12, 2015, 10:09:28 am »

I do a lot of floral, macro-type, photomerging photography using a video head tripod that has a center lift mechanism in the tripod.
I can't seem to get consistent results between the technique of moving the center shaft up/down or simply rotating the video
head to overlap the images the appropriate 30-40%.

I'm growing weary of manually aligning the overlap when the "merge to panorama" doesn't work in PS CC.
In an ideal scenario...what might I do differently?

The higher the magnification ratio, the more 'error' get introduced.

Camera shifting (vertical or horizontal), leaving the sensor in the same plane, should produce better results.  I also will assume focus has not changed, nor the sensor to subject distance.   I also assume you are correcting lens distortion in the RAW file before trying to merge them.

I have to admit, I've don't try multi-shot images when shooting close-up.  My solution was the D810 to give me more pixels in a single shot.  In fact, I find now that a focus stacked imaged, done well, enlarges better than any success I ever had trying to do multi-shot close-up. 
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wmchauncey

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Re: Photomerge shooting techniques
« Reply #3 on: February 12, 2015, 10:41:33 am »

That's good to hear...can't wait for June to roll around for the 5Ds to be released.     ;)
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Bart_van_der_Wolf

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Re: Photomerge shooting techniques
« Reply #4 on: February 12, 2015, 10:51:12 am »

In an ideal scenario...what might I do differently?

I suggest using a proper no-parallax-point camera setup. For single row stitches, you don't need that much gear, just a fore/aft slider to align the entrance pupil of the lens with the axis of rotation, and a means to rotate the camera itself on that axis. Something like this:


Cheers,
Bart
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dwswager

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Re: Photomerge shooting techniques
« Reply #5 on: February 12, 2015, 02:42:18 pm »

I suggest using a proper no-parallax-point camera setup. For single row stitches, you don't need that much gear, just a fore/aft slider to align the entrance pupil of the lens with the axis of rotation, and a means to rotate the camera itself on that axis. Something like this:


Cheers,
Bart

Concur on this as that is what I use for horizontal multi-shot images.  Sometimes I put a tilting monopod head centered on the axis of rotation of the panning clamp, in the panning clamp and put the nodal slide in the monopod clamp.  Then I pull the nodal point over that same vertical rotation axis.  This when I need to shoot at a downward or upward angle to horizontal.

This is a bitch for trying to do multi-shot in a vertical direction.  At least on my Arca Swiss B1 ball head.  If you have the vertical shift capability necessary to cover the image (relatively small for close up work) that is stable, then that is, in my opinion, a much better option.  If you only need say 4" of camera travel, then oh hell yeah, that is much easier.  You will get some flex in the center column.

To do vertical multi-shot using a panning motion, you need something like below to keep the nodal point of the lens centered over any axis of rotation.  This is a multi-row, multi-column setup.:
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Bart_van_der_Wolf

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Re: Photomerge shooting techniques
« Reply #6 on: February 12, 2015, 03:24:07 pm »

This is a bitch for trying to do multi-shot in a vertical direction.

Just keep this at the top of a ball-head or such and rotate the ballhead 90 degrees left or right with the camera lens pointing forward. Now the camera can do a single column series without creating parallax issues.

Cheers,
Bart
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dwswager

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Re: Photomerge shooting techniques
« Reply #7 on: February 12, 2015, 04:31:56 pm »

Just keep this at the top of a ball-head or such and rotate the ballhead 90 degrees left or right with the camera lens pointing forward. Now the camera can do a single column series without creating parallax issues.

Cheers,
Bart

Yeah, I know I can flop the ball head over to get vertical, but never found it real convenient.  Which is one reason I have L-Plates on my camera bodies.  Of course with L-Plates you can put the camera in a landscape orientation while panning vertical.

Question:  Does the no-parallax point of a lens shift significantly with focus distance? When I test my lenses to compile the list of no-paralax points, I am normally focused at a mid distance of about the hyper-focal distance at f/16.  Obviously, for closeups it's going to be focused much closer.

Aw crap, now I have the urge to go out and play!  ;D
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Bart_van_der_Wolf

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Re: Photomerge shooting techniques
« Reply #8 on: February 12, 2015, 04:53:24 pm »

Question:  Does the no-parallax point of a lens shift significantly with focus distance? .

That depends on the lens. If the lens uses internal focusing that doesn't move the entrance pupil, then the NPP remains good. However, if the entrance pupil does move with focusing (most likely the lens barrel gets longer/shorter),  then one should separately calibrate the NPP for such short focus distances.

Quote
When I test my lenses to compile the list of no-paralax points, I am normally focused at a mid distance of about the hyper-focal distance at f/16.  Obviously, for closeups it's going to be focused much closer.

Yes, I also have a list of NPPs for medium to close focus distances for landscape/architecture/interior panos. The parallax issues at infinity are going to be negligible anyway, so it's better to get the closer distances without parallax.

Focusing on stuff that's really close-up, will probably result in some background blur anyway, because DOF rapidly gets less at closer distances.

Cheers,
Bart
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wmchauncey

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Re: Photomerge shooting techniques
« Reply #9 on: February 12, 2015, 05:35:35 pm »

FWIW, I use a 180 macro mounted on a Canon 1Ds3>shoot tethered using Canon Utility Software that allows complete
computer control of the camera settings, including focusing>numerous images are taken for stacking purposes, those
stacks are what I finally photomerge.      ;)
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dwswager

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Re: Photomerge shooting techniques
« Reply #10 on: February 12, 2015, 07:27:55 pm »

FWIW, I use a 180 macro mounted on a Canon 1Ds3>shoot tethered using Canon Utility Software that allows complete
computer control of the camera settings, including focusing>numerous images are taken for stacking purposes, those
stacks are what I finally photomerge.      ;)

I use Helicon Remote for that.  So I assume you are not changing the far or close focus distance, no other settings such that the software in taking the same number of shots at the same focus distance for each set so the only difference is the vertical camera movement or panning.

I haven't done focus stacking with multi image stitching.  I think there is a specific preferred order, but can't remember if it is focus stacking first, then stitching or other way around. 

I recommend you try a single shot (non focus stacked) image set and see if it aligns and stitches properly.
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Bart_van_der_Wolf

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Re: Photomerge shooting techniques
« Reply #11 on: February 13, 2015, 03:42:21 am »

FWIW, I use a 180 macro mounted on a Canon 1Ds3>shoot tethered using Canon Utility Software that allows complete
computer control of the camera settings, including focusing>numerous images are taken for stacking purposes, those
stacks are what I finally photomerge.      ;)

Photoshop's focus stacking capabilities are limited, especially lacking control over the process.

Helicon Focus and Zerene Stacker are the industry leading applications for that functionality. I use HeliconFocus for many years already, and they offer a stellar tool (also a companion program called Helicon Remote for Android Phones/Tablets to control the camera in making the focus stacking sequence). Lot of time saving functionality, like automatic dust spot removal, very good resampling algorithms, and a good Retouching tool that allows to use image data from any of the source images when painting or cloning on the resulting stacked image.

The focus stacked results can then be stitched with a capable pano stitcher like PTGUI (Professional).

Cheers,
Bart
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Petrus

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Re: Photomerge shooting techniques
« Reply #12 on: February 13, 2015, 06:02:40 am »

In an ideal scenario...what might I do differently?

When you merge the photos they MUST BE TAKEN FROM THE SAME EXACT SPOT. That means you have to turn the camera around the front entrance pupil of the lens. Never lift it or move it sideways or just turn it on the ball head as is. Objects near and far from the lens must keep the same alignment. If the entrance pupil of the lens does not stay in place, near-far alignment in separate frames will differ and the frames will not align.

Check this: http://www.vrphotography.com/data/pages/techtutorials/technotes/nodalptalign-tn.html
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dwswager

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Re: Photomerge shooting techniques
« Reply #13 on: February 13, 2015, 10:21:00 am »

When you merge the photos they MUST BE TAKEN FROM THE SAME EXACT SPOT. That means you have to turn the camera around the front entrance pupil of the lens. Never lift it or move it sideways or just turn it on the ball head as is. Objects near and far from the lens must keep the same alignment. If the entrance pupil of the lens does not stay in place, near-far alignment in separate frames will differ and the frames will not align.

Check this: http://www.vrphotography.com/data/pages/techtutorials/technotes/nodalptalign-tn.html

I suggest this only applies if there is rotation involved. Hence you want to revolve the sensor about the no parallax point of the lens.  If you raise the camera 3" say while the sensor (and by happenstance) the nodal point remain in the same planes as the 1st shot, then the 2 will stitch fine.  This is because you are not introducing parallax issues at all and of course, keystoning (the off axis angle to vertical and horizontal lines) will remain consistent
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Petrus

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Re: Photomerge shooting techniques
« Reply #14 on: February 13, 2015, 10:57:08 am »

I suggest this only applies if there is rotation involved. Hence you want to revolve the sensor about the no parallax point of the lens.  If you raise the camera 3" say while the sensor (and by happenstance) the nodal point remain in the same planes as the 1st shot, then the 2 will stitch fine.  This is because you are not introducing parallax issues at all and of course, keystoning (the off axis angle to vertical and horizontal lines) will remain consistent

I do not quite understand. Certainly there are parallax issues no matter which way you move the camera unless the front nodal point remains stationary. Taking a vertical panorama is no different from the normal horizontal one.
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dwswager

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Re: Photomerge shooting techniques
« Reply #15 on: February 15, 2015, 10:17:04 pm »

I do not quite understand. Certainly there are parallax issues no matter which way you move the camera unless the front nodal point remains stationary. Taking a vertical panorama is no different from the normal horizontal one.

When you take a vertical panoramic image, you tilt the camera in the vertical direction changing the angle of the sensor with respect to the image plane and therefore keep the point of rotation around the no parallax point to minimize parallax errors.  If you take multiple shots by moving the camera vertically, then there is no change in aspect of the sensor to the subject.

Parallax is when foreground and background objects change position relative to each other when you rotate the camera.  When you move the camera in the vertical plane only, foreground and background objects don't change relative to each other, you only change the view encompassed by the camera.
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elf

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Re: Photomerge shooting techniques
« Reply #16 on: February 16, 2015, 01:08:01 pm »

  When you move the camera in the vertical plane only, foreground and background objects don't change relative to each other, you only change the view encompassed by the camera.

A simple diagram will show you the error of your statement.
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Petrus

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Re: Photomerge shooting techniques
« Reply #17 on: February 16, 2015, 03:02:42 pm »

Parallax is when foreground and background objects change position relative to each other when you rotate the camera.  When you move the camera in the vertical plane only, foreground and background objects don't change relative to each other, you only change the view encompassed by the camera.

Sit down in a chair, then stand up. With eyes open.
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dwswager

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Re: Photomerge shooting techniques
« Reply #18 on: February 16, 2015, 05:25:16 pm »

Sit down in a chair, then stand up. With eyes open.

Gotcha!  Not sure what was going on in my head.
« Last Edit: February 16, 2015, 09:39:59 pm by dwswager »
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