dynamic distortion correction

Dear Guido @gfuh,

As long as the lens is not a fisheye lens, the optical distortion correction should work. The assumption is that the lens is a so called "rectilinear" lens, which all normal lenses are 😉

The optical distortion correction in APP will dynamically correct for pincushion, barrel, moustache and even more complex forms of distortions from the ideal "rectilinear" projection.

https://en.wikipedia.org/wiki/Distortion_(optics)

The problem with Fisheye lenses is that almost all of them have different projections, there is no real standard and therefore we do not yet support correcting Fisheye projection lenses.

Please let us know if this answers your question.

Mabula

Hi Mabula,

thanks for the answer. Yes I´m using the Tokina SD 11-16 F2.8 lens which is a rectilinear lens. My question came up when I tried to make an mosaik from two Milkyway sessions I made last year.

Thoug I croped the single stacked frame quite strong APP was not able to match the pictures correctly. Therefore my question was more like: Reaches APP in this cases it´s limits, or is it only a question of finding the right distortion margin? Do you perhaps have recommendation for which distortion margin should be used with different optics?

@gfuh When creating mosaics APP needs to be configured in a certain way. Can you make sure that you set the following parameters?

• Tab 3
  • disable automatic
  • slide the number of stars to at least 2500
• Tab 4
  • set the pattern to quadrilaterals or triangles
  • set the scale to 5 - 15
  • enable "use dynamic distortion correction"
  • disable "same camera and optics"
  • registration mode mosaic
• Tab 5
  • mode advanced
• Tab 6
  • enable MBB and set it to at least 10%

More tweaking of these and possibly other parameters may be necessary to get a good result.

Hi Wouter,

yes, that are the parameters I´m using. I guess that the distortions of this small focal lenses are too strong for good results.

BR guido

Heureka! 😀 It works!

Milkyway with lightpollution of the coast. Taken last year at the baltic sea (Fehmarn). Just 3 quick Sessions with 10 x 30sec. pics each without guiding.

BR Guido Fuhrmann

Nice! I guess you tried a different projection?

Hi Vincent,

yes, I set the distortion margin on 0.32 and the projection on mercator Projection. But it´s still a kind of trial and error for I still don´t know what the distortion margin exactly is doing to the data.

BR

Guido

I think that is indeed a bit of trial and error. I do know Mabula wants to improve on this as well, horizon to horizon projections are tricky. But well done on the result I'd say!

Thank you very much.

Guido