I have a 5D m2 with a Canon 17-35 lens ---no matter what I do I can't find a Nodal Point on the rail [Archive] - Nodal Ninja Forum

PDA

View Full Version : I have a 5D m2 with a Canon 17-35 lens ---no matter what I do I can't find a Nodal Point on the rail



sallie
02-24-2012, 02:27 PM
It seems that the nodal point is "off" the rail---in other words the camera would have to sit back further than the length of the rail allows it to.

Also, when trying to find a nodal point (due to the "distortion" in the lens in VERTICAL position) it skews the picture anyway.

I am extremely frustrated and am about to just quit. I am wondering if I should be testing for the NP with the camera in a horizontal position but that doesn't seem possible iwth the NN 5 with the R16.

I hope someone has some suggestions because I have put in 2 solid days trying to find the nodal point with this lens.

I have PTGUI and wonder if that allows for any mistakes--

Thanks
sallie

360texas
02-24-2012, 04:29 PM
Would you please take a photo of your camera/ bracket SIDE VIEW.. and post it here so we can see if the assembly has been completed properly. I have actually seen others installed the camera /top rail backwards. Uploaded photo should be about 800 pixels wide so as not make the right side fall off the page.

Thanks in advanced.

hindenhaag
02-25-2012, 12:37 AM
Hi,

Sometimes it really can be frustrating.

http://wiki.panotools.org/Entrance_Pupil_Database

You can not find your lens in this list but you find the 16-35mm and the 17-40mm. Both of them have and L2 around 70mm: 79 and 71mm. You have to add L1 from camera list above the lens list: 38.5 mm for 5DMKII. L1 + L2 = 109.5mm for 17-40m.

I know it might be totally different for your lens. But often principals of constructions are similar. So I would start at around 105mm for URS = Upper Rail Setting. With a reference point in front related to a point behind it move clockwise and check the reference point: is he moving with the lenses moving aside, you have to move the camera forward on the rail: 105 +x mm. In case it is moving against the lenses movement you have to go backwards on the rail: 105 -x mm. When it turns its directions, you passed by the NPP.

There are some lenses which get settings for the entrance pupil lying behind the sensor and not in front. For example Nikkor 18-200 >= zoom 105. Or Nikkor 70-200. In this case you have to swap around the Upper Rail by 180 to the front side of the Upper Rotator to find your URS.

Check John's Tutorial: http://www.johnhpanos.com/epcalib.htm

At least start to test near the red ring and move backwards by 5mm step by step till the reference move side changes. Than go back to the last 5mm interval and move forward mm by mm.

Some rare lenses do not follow the normal way that NPP moves from front to the mounting flange of the lens from "17 - 40". Some lenses change direction at different zoom settings. You can see this when the lens parts are moving to different direction when you set your different zoom positions. Moving forward and backwards.

Just keep cool. Start up again after reading all the hints. In case you end up behind the sensor, just ask again about the swapping of the upper rail and I will send you pics about it. But it would be the first lens in this focal lens area for me being behind the sensor. But I did not test Canon lenses, sorry.

Anyway, feel free to ask. And do not get bored. You always hear " it just takes minutes". Yes, when you are experienced and trained. But I had the same frustration as you in my beginning.:confused1:

Cheers,
Heinz

John Houghton
02-25-2012, 01:46 AM
I have put in 2 solid days trying to find the nodal point with this lens.
You can set up the head by eye sufficiently accurately for many purposes in only a few minutes. All you have to do is set the aperture to f/22, point the eyepiece of the camera towards a bright light such as a window (or shine a small LED torch into the eyepiece), and then look into the lens. Press the depth of field button on the lens to stop down the lens to the preset f/22 (the camera needs to be ON for this to operate, of course). You will see the aperture as a small bright spot. You can easily judge its position with your two eyes. That is the no parallax point about which you need to rotate the camera.
.
If you operate the zoom control, you will see that the spot moves back towards the camera as you increase the focal length. If you rest a finger on the lens barrel, you can move it to position where it looks to be at the same distance away as the spot. You need to position the camera on the top rail so that the point on the barrel marked by your finger is in line with the centre of the upper rail rotator. Likewise, the spot needs to be horizontally positioned in line with the centre of the bottom rail rotator. You can check this with a simple plumb line (a key on a length of thread). Then the spot should remain in the same place as you rotate the camera vertically and horizontally.
.
That's not going to be super accurate, but I've taken perfect panoramas with my NN5 set up that way in less than five minutes, which is a big improvement on the 2 days you have spent on this. See the tutorial that Heinz supplied a link to(epcalib.htm) for full details of refining the settings.
.
John

sallie
02-25-2012, 11:00 AM
Hi,

Sometimes it really can be frustrating.

http://wiki.panotools.org/Entrance_Pupil_Database

You can not find your lens in this list but you find the 16-35mm and the 17-40mm. Both of them have and L2 around 70mm: 79 and 71mm. You have to add L1 from camera list above the lens list: 38.5 mm for 5DMKII. L1 + L2 = 109.5mm for 17-40m.

I know it might be totally different for your lens. But often principals of constructions are similar. So I would start at around 105mm for URS = Upper Rail Setting. With a reference point in front related to a point behind it move clockwise and check the reference point: is he moving with the lenses moving aside, you have to move the camera forward on the rail: 105 +x mm. In case it is moving against the lenses movement you have to go backwards on the rail: 105 -x mm. When it turns its directions, you passed by the NPP.

There are some lenses which get settings for the entrance pupil lying behind the sensor and not in front. For example Nikkor 18-200 >= zoom 105. Or Nikkor 70-200. In this case you have to swap around the Upper Rail by 180 to the front side of the Upper Rotator to find your URS.

Check John's Tutorial: http://www.johnhpanos.com/epcalib.htm

At least start to test near the red ring and move backwards by 5mm step by step till the reference move side changes. Than go back to the last 5mm interval and move forward mm by mm.

Some rare lenses do not follow the normal way that NPP moves from front to the mounting flange of the lens from "17 - 40". Some lenses change direction at different zoom settings. You can see this when the lens parts are moving to different direction when you set your different zoom positions. Moving forward and backwards.

Just keep cool. Start up again after reading all the hints. In case you end up behind the sensor, just ask again about the swapping of the upper rail and I will send you pics about it. But it would be the first lens in this focal lens area for me being behind the sensor. But I did not test Canon lenses, sorry.

Anyway, feel free to ask. And do not get bored. You always hear " it just takes minutes". Yes, when you are experienced and trained. But I had the same frustration as you in my beginning.:confused1:

Cheers,
Heinz

Hi Heinz

thank you for expressing what I feel---that this can be frustrating! When I got up this morning and thought about it I realized that I could flip the top horizontal slider so it is "behind" the tripod and then I might be able to find the nP---for some really lucky reason I haphazardly put the camera on and looked through the lens, moved it left and right and the pole didn't move---so found it! When I tested the full range of the lens at 24 mm and then 35 mm the nodal point stayed the same---though that doesn't make any sense!

I will mostly be using the lens at 16 mm so at least that is covered.

Again, many thanks to everyome for your help!:biggrin:

John Houghton
02-25-2012, 12:16 PM
The 17-35mm lens appears in this list: http://www.swissarmyfork.com/lens_table_1.htm . The entrance pupil (no parallax point) moves over a range of 4.5mm over the full zoom range according to that.

John

hindenhaag
02-25-2012, 09:37 PM
Sallie,

Nikkor 17- 55mm/f2.8 has the same URS of 110mm @ zoom 45 as well as @ zoom 55. So you could be right with the setting. Just re test and then shoot a pano and stitch. There are even such rare situations that the camera has to be set "on top of the upper rotator". Which you can only do by use of an adapter. Some are settings are stopped by length of the upper rail.

Anyway, your lens seems to be one of the special one. When I tested the Nikon kit lenses I was already used to the to be found behind the "Entrance Pupil behind the sensor". So I swapped the upper rail to the front.

By the way, this would be the same with M1 Series, just place the upper rail into the Rotator clamp showing to the front.

In case you do not know the page: http://www.vrwave.com/panoramic-lens-database/canon/

So for all looking for settings: first look to http://wiki.panotools.org/Entrance_Pupil_Database For lower rail setting = LRS measure H and add 13mm offset for NN5 for example. For URS add L1 + L2

In case you do not find the lens: http://www.swissarmyfork.com/lens_table_1.htm the list is not updated since years, most lenses are Nikkor lenses. But the old "Bible". Use Entrance Pupil measurements = NPP. In case this is negative = -xxx mm, the npp is behind the sensor = "Film Plane". Measurement goes from lens flange to Entrance pupil. So similar to the wiki table you have to add L1 = distance from lens flange to tripod screw socket to the result of the lens table. Entrance pupil result = L2. End Result L1 + L2.

Enjoy, pleasure to try to help you.

Heinz