Nodal Point and Tripod Heads

[dandaluzphotography]

Hi Guys,

I'm tried to get a panoramic shot of NYC from Weehawken, NJ using 5 different images and stitching them together using CS5 and it didn't work out.

I've been reading some stuff about the nodal point and I understand the nodal point comes into effect for nearby objects, but does it matter if I am shooting a cityscape from some distance away?

Another question I have is about the tripod head I am using. I have a Manfrotto pistol grip. Jumping ahead a little bit, when I stitched the images together (it was 5 of them) I noticed the buildings were crooked and so was the shoreline. I tried using all the different options CS5 provides for this but all came out the same. When I examined each image individually, I noticed none of the pictures was particularly straight and that's probably why the buildings were crooked. I thought the stitching software would line these up but I guess that's not the case.

Anyway, my plan is to try this again, this time using a point of reference on the cityscape to keep the camera leveled through all five images. Do you guys think this would work? I don't have a panoramic head for the nodal point, but I might not need that based on how far I will be taking the pic from.

Any help would be appreciated.

Thanks,
Danny

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[Big Mike]

I think this is easier with a head like a 3-way or a pan-tilt, because you don't have the freedom of a ball head to contend with. I think that what I did/do, is to rotate the centre column, rather than unlock and relock the ball head. But first, I do my best to level the tripod and try to have it set so that a reference like (horizon etc.) is level on both ends of the range that I plan to shoot.

It's not as good as having a head that is meant for this type of thing, but it helps. I too have run into problems when trying to stitch pano in Photoshop. There are several options, so if it doesn't work, try selecting a different method for Photoshop to try.

Also, try not to use a wide angle lens because the distortion will make it hard to stitch. Another tip is to turn the camera to a vertical orientation. You have to take more shots, but you will have less distortion between the images. Don't forget to give a generous overlap between images.

[dandaluzphotography]

Thanks Mike. I actually used my 70-200 mm lens at about 80mm. What I didn't do is take the shots in portrait mode. This cut off a good portion of the top and bottom of the image when I had to crop (to get rid of the white) after the stitch.

I have a manfrotto tripod that doesn't let me rotate the center column due to the shape of the column.

Thanks,
Danny

[KmH]

I have a manfrotto tripod that doesn't let me rotate the center column due to the shape of the column.

Another reason some of us don't recommend Manfrotto tripods.

[tirediron]

It sounds to me like your tripod wasn't level. The nodal point has very little impact on images such as cityscapes. All of my panoramas in this gallery were taken assuming the nodal point to be the lens mount for ease of calculation.

John's basic 'How-to' guide to Panoramas...

1. In order to get a good pano, your camera has to be level, and has to rotate around the nodal point. This the point at which the image inverts. For practical purposes, with most lenses, using the sensor plane will work fine. What this means is that you have to shoot from a tripod for best results.

Therefore, put your camera on your tripod and level it. Even though my tripod legs and head both have levels built-in, I carry a small dollar-store spirit level in my camera bag to make sure everything is as close to level as I can get it.

2. Once I'm satisfied that everything is level and square and my tripod is locked (except for the rotating axis) where I want it, it's time to work on the exposure. Another important factor is to NEVER SHOOT PANOS IN AUTO! Set your camera to a manual or semi-manual mode (I use full manual, but either shutter or apeture priority will work as well).

Determine the range of your pano (eg the left and right limits) and then go through and meter the different areas. Find out what the camera is recommending as maximum and minimum exposure, and when you've done this for the full range of the image, then average the settings. Don't change these settings; yes some will likely be slightly under exposed, and some slightly over, but deal with it in post.

3. Now you're ready to start shooting. I always start at the left-hand end of the intended pano and work right, simply so that the images are in the correct order when they're on my computer, but that's up to you. Expose the first image, and choose a landmark about 2/3 of the way to the right-hand side of the frame. Now, being careful to ensure that you don't upset your level, move your camera so that the left-hand edge of the frame lines up on the land mark you just chose. Ideally you want about a 30-35% (or 1/3) overlap between each image. Continue shooting in this manner until you have the whole sequence captured.

4. Download and stitch using your favorite software.
A few tips: With respect to the issue of exposure: If there is an extreme dynamic range within the pano, (say bright sun to deep shade) I will often bracket each image 1/3 stop on each side, so that for every image used in the pano, you actually expose three. This gives you a bit of latitude in terms of trying to produce an image with a pleasing and realistic dynamic range, but be warned, it often looks hokey.

One of the most important tools you can have for taking panos (aside from a good tripod) are filters. There are two types, one is the circular polarizer (CPOL)for enhancing colours and deepening the blue in sky and the other is graduated neutral density(G-ND); these help to prevent blown skies and preserve detail on the ground. When using a CPOL, it's important to remember not to change it's setting through the course of the pano either. Find the optimum setting and use it at that setting for the whole image. Likewise with your G-ND; don't change their position or intensity.

[tirediron]

I have a manfrotto tripod that doesn't let me rotate the center column due to the shape of the column.

Another reason some of us don't recommend Manfrotto tripods.

What the... ????? Why would you rotate the tripod column?????? You rotate the head. I'm not aware of any tripod where rotating the column doesn't introduce a chance of changing the height of the head. The problem here is that the OP doesn't have the right tripod head for doing pano work. Tilt/pan heads are good, but ballheads with a separate, rotating panorama base (what I use) work just fine as well.

[Big Mike]

If your ball head doesn't have a 'rotating panorama base', wouldn't it be better to rotate the column, or rotate the whole head, rather than unlock the head and try to rotate it without throwing off the level?

[tirediron]

If your ball head doesn't have a 'rotating panorama base', wouldn't it be better to rotate the column, or rotate the whole head, rather than unlock the head and try to rotate it without throwing off the level?

Perhaps, 'though I'm not really sure that it's worthwhile trying to shoot good panoramas without a pano head/3-way head.

[clanthar]

I shoot them hand-held all the time; never have a problem.

I agree more frames and a longer lens and John's point #2 is essential "NEVER SHOOT PANOS IN AUTO!"



Joe

[dandaluzphotography]

It sounds to me like your tripod wasn't level. The nodal point has very little impact on images such as cityscapes. All of my panoramas in this gallery were taken assuming the nodal point to be the lens mount for ease of calculation.

John's basic 'How-to' guide to Panoramas...

1. In order to get a good pano, your camera has to be level, and has to rotate around the nodal point. This the point at which the image inverts. For practical purposes, with most lenses, using the sensor plane will work fine. What this means is that you have to shoot from a tripod for best results.

Therefore, put your camera on your tripod and level it. Even though my tripod legs and head both have levels built-in, I carry a small dollar-store spirit level in my camera bag to make sure everything is as close to level as I can get it.

2. Once I'm satisfied that everything is level and square and my tripod is locked (except for the rotating axis) where I want it, it's time to work on the exposure. Another important factor is to NEVER SHOOT PANOS IN AUTO! Set your camera to a manual or semi-manual mode (I use full manual, but either shutter or apeture priority will work as well).

Determine the range of your pano (eg the left and right limits) and then go through and meter the different areas. Find out what the camera is recommending as maximum and minimum exposure, and when you've done this for the full range of the image, then average the settings. Don't change these settings; yes some will likely be slightly under exposed, and some slightly over, but deal with it in post.

3. Now you're ready to start shooting. I always start at the left-hand end of the intended pano and work right, simply so that the images are in the correct order when they're on my computer, but that's up to you. Expose the first image, and choose a landmark about 2/3 of the way to the right-hand side of the frame. Now, being careful to ensure that you don't upset your level, move your camera so that the left-hand edge of the frame lines up on the land mark you just chose. Ideally you want about a 30-35% (or 1/3) overlap between each image. Continue shooting in this manner until you have the whole sequence captured.

4. Download and stitch using your favorite software.
A few tips: With respect to the issue of exposure: If there is an extreme dynamic range within the pano, (say bright sun to deep shade) I will often bracket each image 1/3 stop on each side, so that for every image used in the pano, you actually expose three. This gives you a bit of latitude in terms of trying to produce an image with a pleasing and realistic dynamic range, but be warned, it often looks hokey.

One of the most important tools you can have for taking panos (aside from a good tripod) are filters. There are two types, one is the circular polarizer (CPOL)for enhancing colours and deepening the blue in sky and the other is graduated neutral density(G-ND); these help to prevent blown skies and preserve detail on the ground. When using a CPOL, it's important to remember not to change it's setting through the course of the pano either. Find the optimum setting and use it at that setting for the whole image. Likewise with your G-ND; don't change their position or intensity.

Hi,

Thanks for the great response!

I believe that was also my problem. The tripod wasn't leveled.

I also have a spirit level that I attach to the hotshoe, but like I mentioned, I didn't really think to level the shots because I thought the software would do that. Big mistake!

I took all the shots from left to right in AV mode and made sure the exposures were all the same length of time. This worked out pretty as all the shots had even exposure.

I use GND's but this situation didn't call for it. It was night. :-)

I believe the main problem was I was not leveled.

You mentioned the Nodal Point doesn't matter with cityscapes. I'm assuming this is because of the distance of what I'm shooting. I have read the same thing, but in what situation would the Nodal Point matter?

Can you expand a bit on this:

...were taken assuming the nodal point to be the lens mount for ease of calculation."

Thanks,
Danny

[clanthar]

I took all the shots from left to right in AV mode and made sure the exposures were all the same length of time. This worked out pretty as all the shots had even exposure.

Don't shoot in AV mode -- that's still Auto. Determine the best exposure for the entire panorama and then lock that exposure in full M. You should also take the auto-focus off -- all auto off.

Joe

[dandaluzphotography]

I took all the shots from left to right in AV mode and made sure the exposures were all the same length of time. This worked out pretty as all the shots had even exposure.

Don't shoot in AV mode -- that's still Auto. Determine the best exposure for the entire panorama and then lock that exposure in full M. You should also take the auto-focus off -- all auto off.

Joe

Makes sense. I will do that, full manual.

I did manual focus. I don't trust my camera's auto focus, especially in low light.

Thanks,
Danny

[tirediron]

Can you expand a bit on this:

...were taken assuming the nodal point to be the lens mount for ease of calculation."

First off, let me rephrase a little: I'm not going to say that the nodal point doesn't matter, but when shooting large scenes, I have never noticed it to matter.

With respect to the above comment, I normally shoot panos with 'D' series primes. When setting up my macro rail I set the swivel point to be right under the lens mount. If I was using something like a 70-200 or long prime I would probably try and set the pivot nearer the nodal point, but with such a short lens, it doesn't seem to matter.

[Big Mike]

Has anyone seen/tried one of those point & shoot digi-cams that can apparently take a pano shot, simply by panning as you shoot?