PC 28mm lens for Pano Stitched Gigapix panos?

[gerard_smulevich]

I'm sure this question may have been addressed before but I could not find a clear conclusive answere in the forums:

 

I'm looking to create large hi-rez photographs from stitched tiled panos in order to print from large files without having

to "up-rez" a 10 mp file (d200). For this I have bought a Nodal Ninja 5 pano head.

 

My question: Since most of my shooting involves architectural/urban subjects, I've been considering getting a pc lens

for my d200. Does a PC lens work well with a pano head setup? Say I were shooting 2 rows, 7-10 images across

(camera mounted in portrait position): would a PC lens (like the Nikon PC 28mm 3.5?) offer me the advantage of

added parallax correction, making the stitched panos "cleaner"? or would the pc lens create weird distortions, edge

fall-off or vignetting that would ruin/compromise the end result when stitching (I use PT-GUI 8.0)??

 

If anyone has had any experience with the use of PC lenses combined with panorama-stitched photography, what

are your thoughts /suggestions on this? Also, with a D200 (1.5 crop) would a 28mm be advisable or a slight longer

35mm? ...or should I really be looking at the 24mm pc-e to get the max wide angle possible?

 

This is what I'm shooting: www.pbase.com/gerards

 

Again, my goal is to generate very large printable files for gallery shows, max IQ, minimum up-sampling.

 

My current lenses are 70-200 2.8, 35-70 2.8, 50 1.8, 35 2.0 (all nikkors) and a Tokina 12-24 dx. Should I add a PC

28mm to my collection?

 

thank you

 

g

[jakob_norstedt_moberg]

PTGui is a very capable software. You can do all you would ever want of perspective correction there. A PC (shift)

lens does not offer any advantage, it just complicates the stiching. If the lens is shifted you will have not only the fov,

a, b, and c parameters to optimize, but also the shift parameters.

<br>

The key to perspective correction in PTGui are the vertical control points. Set them for two know vertical lines and

you will have straight verticals in your output.

<br>

I have shift lenses (35mm PC and 24mm PC-E) and I do a lot of panorama stiching in PTGui but I don't use the shift

lenses for stiching.

<br>

Jakob

[gerard_smulevich]

Jakob:

 

That's very clear, thank you. So: you don't see any "degradation" of your image quality by having PTGUI do the

parallax correction? for example, how does PT GUI's perspective correction affect IQ compared to CS3's

interpolation "transform" tool, which creates new pixels to compensate for the perspective correction?

 

I suppose that if the pc lens interferes with the stitching, then it's out of the question. Interesting. So do you use your

pc lenses at all? Also: do you see a big advantage between the older pc lens and the pc-e?

thank you again

g

[ronald_moravec1]

It depends on how good the stitching sofware is and how much distortion the lens has. The problem is the lenses have some barrel distortion and some software will remove it and others will not. If the lens is in a non-shifted position, the distortion is more easily removed. If shifted, canvas must be added around the picture so the uneven distortion caused by shifting is recentered. It can then be taken out and the stitch done. See PTLens website and Tom explains in better detail.

 

 

http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/PC_Nikkor/index.htm

 

http://www.photo.net/nikon-camera-forum/00DqMu

 

Check out the two links.

 

What works best where recognisable straight lines are present is to shift the lens left-center-riight keeping the lens focal point over the center of rotation, actually you make 2 or 3 exposures moving the body, not the lens.

 

When you rotate as you normally do for panos, a "cigar" distortion becomes evident like a swing lens camer has except you get a series of perspective pictures and the distortion becomes a series of blocks instead of a nice smooth curve like a swing lens produces Cigar distortion may be characterized by thinking of a rectangle photographed from the center and both ends come to perspective points leaving the center wider than the ends.

 

As I see it, the choice becomes better stitching sofware, fixing the distortion manually on a frame by frame basis, making a 2 or 3 frame stitch keeping the lens in one position, or use a swing lens and correct the resulting distortion.

 

Notice how in the example, the maker put the corner wher the overlap occurred. This effective hides the cigar distortion if two frames are used.

 

I did a few panos with a shift lens on film using a 2 frame stitch and the resulting distortion was weird with a recognizeable straight object. Someone here took the photo and corrected it with GUI software and got it back to a perfect rectangular object.

 

http://www.ptgui.com/

 

Give this software a try and see how things work,

 

Perhaps someone with direct experience with the tools you mentioned with assist more exactly.

[marty_allen]

I attended a seminar taught by Bruce Dale (NatGeo for 30 years) this weekend. He talked extensively about using a PC shift lense for Panos. His main point was that with the PC lens he could avoid keystoning. From my personal experience I would challenge you to tell the difference between an PC shift shot pano and one that is not.

[eric friedemann]

Dale's pano tutorial is a good one:

 

 

http://v1.brucedale.com/Panorama%20tutorial%204.htm

 

 

If I were doing stitched panos I'd want to use a PC lens for composition, to be able to raise and lower the horizon line while keeping the camera perfectly parallel to the ground- this goes to Dale's point about keystoning.

[jakob_norstedt_moberg]

Gerard,

<br>

If you want to do perspective correction of a single image it is better to do it right from the beginning, i.e. use a shift

lens. That way you use the best of every pixel on the sensor (supposing the lens is of high quality). Software

correction will always introduce some degrading, although usually quite minor.

<br>

But you want to stich, and by stiching you can get any amount of pixels you want. Then it is preferable to make

things as simple as possible for the stiching software, i.e. use no shift which would increase the number of variables

to optimize. A large number of degrees of freedom will mean a larger probability that optimizing goes berzerk, or at

least introduces new artifacts. You would get simpler optimization, higher pixel resolution and the same perspective

with a few more images and an unshifted 35mm lens than with a shifted 28mm lens.

<br>

I don't use my 35mm PC anymore, it is pre-AI and don't fit on my D3. The 24mm PC-E has tilt and a tilted focus

plane can not be simulated in software.

<br><br>

Eric,

<br>

The keystoning is not a problem with a good stiching software like PTGui. If you do use those vertical control points I

mentioned above you will get no keystoning and a perfect horisontal line no matter if your camera where parallell to

the ground or not. But you have to select a suiting output projection; rectilinear for normal wide angle perspective (up

to say 90 degrees field of view), cylindrical for wider images (up to 360 degrees field of view), or euirectangular as a

base for 360x180 spherical webpanoramas. There are other projections as well which also could be used for special

purposes.

<br><br>

Jakob

[joseph_wisniewski]

The original question was parallax errors. Using the shift lens in conjunction with the Nodal Ninja will not help with parallax correction, at all.

 

A PC lens is also markedly inferior to using the elevation control on the Nodal Ninja to add rows to your multirow panorama.

[gerard_smulevich]

Thank you, all fo you. It seems clear that I should first experiment with my newly arrived Nodal Ninja 5 before I invest in a PC lens. I recieved the NN5 today and it's built like a rock. I did a first 4-image test pano in my living room with available light and it was flawless except for some barrel distortion at 70mm on my 35-70D (great older AF lens,,,better optics than my 35 2.0 prime). I still have to learn how to use PTGUI in its entirety, incl. lens distortion correction.

 

4 shots stitched from my D200 RAW files yeilded a 24"x10" image @300 . that's in a single row. In the morning I will test extensively (it's my day off from teaching...yay). I will report results.

 

Thank you all once again. I think you saved me about $500 in an unneeded pc lens. Now I must find ANOTHER lens to invest in :)

[oskar_ojala]

If you want a multirow stitched image then it's usually just better not mix shift into the equation. Naturally, software based perspective correction will lose quality, but since you're stitching you should take enough frames so that you have room for losing quality in post processing.