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dhoggan
06-10-2008, 04:03 AM
Hi,

Well, I'm still debating on the kit I need to buy to allow me to take high quality panos and another question has come up that I can't find an answer to. Hopefully it's not too basic a question!

Does the focal length of the lens really matter? I've always used a wide angle for landscape as I wanted to get as much in the shot as possible and obviously a 17mm focal length will get more of the scene than a 70mm. However with panoramas doesn't that become irrelevant. If this is the case, would using my 50mm prime (the Canon f/1.:001_cool: be as good as (or better than) heavy glass such as a Canon 24-105 or lower quality glass such as the Sigma 18-200?

What am I missing?

Regards,

Dave

jonschaeff
06-10-2008, 05:17 AM
hi,

the only thing you should regard, besides the quality of the lenses (i would prefer the canon ones you mentioned) is the change of perspective you have using different focal lenghts. i love my sigma 10-20, it's a great lens but it is not that good to use it @10mm all the time, because the landscape in the back starts sizing down, because the wideangle makes things in the front bigger than things in the back. if you use a moderate wideangle or a normal lens you dont geht this effect. using a tele has got the opposing effect, things in the back become relatively bigger than they are.

an example for the wideangle effect (cliffs of moher, ireland, actually more than 200m high):

http://gebildet.org/irland/15.jpg

one really nice feature of using panoheads is the possibility to use rather moderate angles to produce the picture. you still get a lot of details and the scenery and you dont have to worry about the unnatural effect of wideangle focal lenghts.

greetings.

dhoggan
06-10-2008, 06:47 AM
JOn,

Yes, an excellent point. By that reasoning it's a tossup between the 50mm prime, or the 24-105 set to 50mm. I guess the deciding factor would be if the NN3 can't cope with the larger lens. Some posts in the forum suggest it's OK, some (including a reply to my previous post) suggest not. I would prefer to use the 24-205 as I have confidence in it's quality. The 50mm is a bargain basement Canon prime that I have little experience in.

Dave

John Houghton
06-10-2008, 06:58 AM
The basic fact you should understand is that you can take your panorama with any lens and the end result will have exactly the same general appearance. The lens focal length will determine the maximum resolution of the stitched image and how many shots are needed to cover the desired angle of view. The smaller the angle of view of the lens, the more shots you need, but more detail will be captured in the images resulting in a higher quality final panorama. You need to decide exactly what you want to end up with in order to work backwards to determine what lens you need to use.

John

Mauro Contrafatto
06-10-2008, 09:10 AM
Another point in choosing the focal lenght for a panorama is the number of shots required by the scene. For example, if you have the sea in a part of the panorama, it could be impossible to stich adjacent images together because of the waves not standing still. The same happens when a lot of people is moving around the camera.

Another problem, if the are near objects as well as distant elements in the scene, is the reduced depth of field of an higher focal lenght lens which must be taken into account.

That's is why fisheye or extreme fisheye lens are normally used for full spherical panos.

dhoggan
06-10-2008, 10:10 AM
OK, so it's not simply a case of sticking with 50mm for every shot and I'll be fine! I suspected as much.

The point about moving components (waves, river, people, cars etc) is well made. If these exist, then wider angle, but lower resolution. If there's foreground interest as well as the main scene, then wider angle again.

In short, the choice of focal length is not so much personal preference, but one of what the scene is, correct?

Thanks,

Dave

jonschaeff
06-11-2008, 01:49 PM
The basic fact you should understand is that you can take your panorama with any lens and the end result will have exactly the same general appearance.



this is wrong, the choice of the focal lenghts has not only influences on the numberof images needed and the resolution, it really changes the pictures, reasoned by simple physics. it is also not possible to correct the strange perspective of ultrawideangle lenses with ptlens or others.

John Houghton
06-12-2008, 07:44 AM
this is wrong, the choice of the focal lenghts has not only influences on the numberof images needed and the resolution, it really changes the pictures, reasoned by simple physics. it is also not possible to correct the strange perspective of ultrawideangle lenses with ptlens or others.


Stitching programs such as PTGui can accurately remap images from ultrawide lenses such as fullframe and circular fisheye lenses to spherical or rectilinear projections, amongst many others. PTLens is not needed. Perspective and barrel distortions can usually be very adequately corrected. It just isn't true that the extreme distortion of a fisheye lens will somehow make its presence felt in the final stitched panorama image. To prove my point, I took a test panorama with a Sigma 20mm rectilinear lens and a Sigma 8mm circular fisheye this morning. I stitched to cylindrical format as it covered only 240 degrees, and you can see both stitches here:

http://www.johnhpanos.com/20-8comp.jpg

As you can see, these are virtually identical as far as the general appearance is concerned (perspectives, geometry, distortion, straight vertical lines).

If your stitching program cannot do as well as this, you should try one of the Panorama Tools based programs (PTGui, PTAssembler, Hugin) or Autopano Pro. With some practice, you can hope to get similar results.

John

Terrywoodenpic
06-12-2008, 10:32 AM
http://www.johnhpanos.com/20-8comp.jpg

As you can see, these are virtually identical as far as the general appearance is concerned (perspectives, geometry, distortion, straight vertical lines).

If your stitching program cannot do as well as this, you should try one of the Panorama Tools based programs (PTGui, PTAssembler, Hugin) or Autopano Pro. With some practice, you can hope to get similar results.

John


Something odd going on with the door jamb though. :ohmy:

John Houghton
06-12-2008, 10:46 AM
Ah! Thanks. I didn't notice that. What happened was that I removed the camera from the NN5 to take it indoors to change lenses as it was windy. As I was taking the second set of shots, I noticed I had not closed the patio door and the curtain was blowing about. I closed the door and retook the last shot which had the door open before continuing. When I added the images into PTGui , I forgot I had one shot duplicated - with the door open and closed. The blender has obviously decided it would be fair to have half of one and half of the other. I will correct it.

John

Macro
06-12-2008, 05:12 PM
Ah! Thanks. I didn't notice that. What happened was that I removed the camera from the NN5 to take it indoors to change lenses as it was windy. As I was taking the second set of shots, I noticed I had not closed the patio door and the curtain was blowing about. I closed the door and retook the last shot which had the door open before continuing. When I added the images into PTGui , I forgot I had one shot duplicated - with the door open and closed. The blender has obviously decided it would be fair to have half of one and half of the other. I will correct it.

John


Thanks for the nice example, John.
I had noticed the curtain at the top of the door frame, but why was the open door not visible?

John Houghton
06-12-2008, 11:47 PM
I think the curious way the images were blended was just a quirk of Smartblend, which attempts to position the seam around features to minimise the effects of parallax and movement.

John

jeffegg2
08-09-2008, 07:31 PM
I have the Sigma 10-20 for my Nikon D40.

I notice that when I take more shots (more detents) there is less of the jumping in and out that I notice with ultra wide angles. Wouldn't this also be reduced using a more conventional lens like the 18-55 kit lens? I would like to reproduce the panoramas that I see that contain virtually no distortion.

John Houghton
08-10-2008, 12:25 AM
Generally speaking, it doesn't matter what lens you use and how distorted the images look, any distortion is not carried forward into the final panorama when a good stitching program is used. Programs like PTGui and Autopano Pro are able to correct the distortion so that the final panorama will look the same, differing only in terms of resolution and general image quality. Likewise, the number of detents used shouldn't make any difference provided the images overlap. With more detents, you will use less of the outer edges of the images where the image quality can fall off, so the overall quality of the panorama might be slightly better. However, the panorama would show no more distortion that one taken with fewer detents. This does assume that the stitching program is expertly used. Automatic stitchers often don't correct distortion accurately without some manual assistance from the user.

John

lckt13
09-18-2008, 12:55 PM
Hi Dave, i was the circlepix area manager for 6 years. at the end of my tenure we were using the Nikon D40 with the standard 18-55 mm Nikkor lens that came bundled with the camera. i taped my lens wide open to the 18mm setting to get the widest angle possible especially for the interior virtual tours.

Since I started my own company i still use the Nikon D40 but this time with the Sigma 10-20mm lens again taped to the widest opening at 10mm. I use the circlepix rotator which i purchased from circlepix while an employee. it is outstanding. i also own the older Ninja n3 but it is flimsy for a D40 with the Sigma lens and a S600 Flash. it wobbles so i have it as a backup to the circlepix rotator.

i get lens distortion on the edges which is noticeable on vertical lines such as doorways etc. its not bad and for landscapes it is not noticeable at atll. the abberration (sp?) can be eliminated in cs3 using either transform/skew or lens distortion correction.

i have heard the Nkion DX 12-24mm eliminates this distortion since it is an aspherical lens. i have one on loan coming from Nikon Pro to test. i will post the results after using the lens upon its arrival.