Lens correction for Powershot D30 - DNG development with darktable

  • 4 Replies
  • 6079 Views
Advertisements
I use darktable for developing DNG files from my Powershot D30.
Unfortunately there is no lens correction profile available for the D30 from the lensfun library that is used in darktable.

Does anyone have an idea what comparable Powershot lens correction profile I could use to successfully execute the correction. In other words - anyone knows what type of camera/lens is inside the D30 or is it totally different from all other models?

I already tried a couple of lens corrections from other Powershot models but none was satisfying. As I don't need it too often I want to avoid to try creating a lens correction profile on my own - and as I never did before I'm unsure if I am able to.

*

Offline reyalp

  • ******
  • 11541
Re: Lens correction for Powershot D30 - DNG development with darktable
« Reply #1 on: 23 / June / 2016, 17:28:00 »
Does anyone have an idea what comparable Powershot lens correction profile I could use to successfully execute the correction. In other words - anyone knows what type of camera/lens is inside the D30 or is it totally different from all other models?
I don't know if it shared lens hardware with another cameras, but trying ones released around the same year with the same focal length range and sensor size wouldn't hurt. The dpreview camera table and compare tool may be helpful to find them: http://www.dpreview.com/products/canon/cameras?subcategoryId=cameras

Edit
Obvious one to try would be d20.
« Last Edit: 23 / June / 2016, 17:29:48 by reyalp »
Don't forget what the H stands for.

Re: Lens correction for Powershot D30 - DNG development with darktable
« Reply #2 on: 27 / June / 2016, 11:17:30 »
Thanks for the tipp, reyalp. I already checked cameras with equal looking lens around the time when the D30 was released but none of them either had a lens correction profile in lensfun library or one that fits to the D30.

The D20 seems to have the same lens but the problem is - there's no lens correction profile for that camera as well.

I keep investigating and if I'm not successfull I will try to create a lens correction profile ... somehow...

*

Offline blackhole

  • *****
  • 613
  • A590IS 101b
    • Planetary astrophotography
Re: Lens correction for Powershot D30 - DNG development with darktable
« Reply #3 on: 27 / June / 2016, 11:32:13 »
Lens profiles is not a problem to do, but someone with a camera should record a calibration image, and upload them somewhere.It requires a few hundred megabytes of data traffic.


*

Offline Anaglyphic

  • ***
  • 129
  • Anaglyphic lives!
Re: Lens correction for Powershot D30 - DNG development with darktable
« Reply #4 on: 04 / July / 2016, 13:03:21 »
As I don't need it too often I want to avoid to try creating a lens correction profile on my own - and as I never did before I'm unsure if I am able to.

I promise you, you are able to. But, 2 things:

1) Don't need it too often? - Lens distortions don't turn off and on. If you need it, you always need it. And with cheap ($200) cameras come cheap sensors and cheap lenses. You definitely could benefit from it, especially if you shoot underwater, the blue channel gets massively distorted. While you can compensate for pincushioning/barrel distortions by eye somewhat, even on the JPEGs, there's nothing you can do about chromatic aberrations. Some plugins can fake it, by using in-painting around the color fringes, but to truly remove tCA you need the RAWs. (once it's been demoasic'd it's nearly impossible to truly remove tCA, or adjust white balance correctly, or, or, or... this is why we shoot RAWs.)

2) CHDK, Darktable, dcraw, exiv2, lensfun, etc... most of all of the software you are using is OSS... get in the spirit of things and learn to profile your lenses. You will gain a better understanding, and more knowledge is always a good thing, not to mention you may help out another less-capable D30 user if you upload your results to the lensfun forum, or hugin/panotools, or both! Avoid it? NO! Embrace it! :-)

Yes, they can be time consuming to create, especially in that you have to do everything twice if you want underwater corrections as well as above... but how much or how little you do is up to you. If you mainly shoot above water at fully wide and fully zoomed? Just start with correcting those two positions. Come back later and do the rest. Or get motivated and do it all at once!

If you Google for creating lens profiles you will get many hits...

... and if you REALLY really don't think you can handle it, and want to give it to someone else to do the work for you, Torsten Bronger does allow uploads for image calibration... but please make a donation to the project if you go the lazy route: Lensfun calibration
Since we cannot know all that there is to be known about anything,
 we ought to know a little about everything.
-- Blaise Pascal

 

Related Topics