Question about calibrating lens in Hugin

[David W. Jones]

Good afternoon!

I have five lenses I mostly use. One is a prime, another is a 500mm tele.

The other three are zooms.

When calibrating zooms, do I need to calibrate separately for the different zoom lengths?

Thanks!

-- 
David W. Jones
gnome...@gmail.com
wandering the landscape of god
http://dancingtreefrog.com
My password is the last 8 digits of π.

[tbransco]

It seems you do.  You can find some recommendations in this article over on pixls.us?  It's getting a tad outdated, but is likely still useful.

Good luck,

Terry

[David W. Jones]

Oh, excellent article! Thanks, Terry!

I also found out that in Debian Bookworm there's no lensfun‑update-data command, just the GUI version, g-lensfun‑update-data. But it works.

[Jan Steinman]

Yes.

Things like distortion, vignetting, and front nodal point all change with focal length on many (most?) zoom lenses.

For panoramas, I'd calibrate for the widest zoom setting, since that's what you'll probably be using.

[David W. Jones]

Thanks, Jan. Terry on the list sent this article link that is quite thorough:

https://pixls.us/articles/create-lens-calibration-data-for-lensfun/

I'll go ahead and calibrate for the range of lengths. I like lots of sharp details, so I love to zoom in as far as possible and shoot a lot of frames covering a view, instead of zooming out.

I have a friend that always responds to my panoramas by saying, "Why don't you just buy a wide-angle lens instead?" But then, he thinks my interest in producing 10-12-foot long panoramas at 300DPI is silly. 😉

[Erik Keever]

Hi David,

Yes, for a zoom all geometric distortion, chromatic aberration and vignetting parameters are (in general) a function of focal length. Most zooms e.g. will switch from barrel when wide to pincushion when tele'd. For that matter, distortion parameters also depend on current focal distance as this, too, moves the internal optics.

In all truth: I hate to admit it but I honestly confess I'm a bit on the fence when it comes to using Hugin to do these corrections now a days.

On one hand I want to use e.g. LightTable so I can throw my "real" computer's processor at the .CR3 to squeeze the last bit possible out of it. And when I was using a 70D, dcraw (combined with my own high-order chromatic aberration correction code) could often produce an image from a CR2 that was measurably superior to what came "stock" from the camera. But with an R7, honestly, I find that the improvement - if any - that I can get by "rolling my own" is not enough to be worth it. Canon can measure their lens' geometric, chromatic and vignetting distortion far more accurately than I can, and all I need to do to access those coefficients is go into the menu and click 'yes' on distortion and peripheral illumination correction.

-- Erik

--
A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ
---
You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hugin-ptx+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/hugin-ptx/a0101d07-4988-4429-b1e2-27b2ae36b568%40gmail.com.

[Jan Steinman]

"he thinks my interest in producing 10-12-foot long panoramas at 300DPI is silly."

What kind of printer do you have?

I used to have a Roland Hi-Fi Jet. It could do 60" wide, by whatever fit on a roll.

Here's a banner I hung in my art festival tent. It was 10' x 4'.

[David W. Jones]

Hello!

I use RawTherapee to process my photos. It has its own option to load lens corrections, separate from Hugin, but basically does what you're talking about in LightTable.