p.2 #3 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
It looks to me it's following maybe the edge of a internal element or something of this nature to case the light ray bend. It's very strange plus with the natural distortion it could be a combination. Just thinking out loud on it. We may need a lens designer to explain this
p.2 #4 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
GMPhotography wrote:
It looks to me it's following maybe the edge of a internal element or something of this nature to case the light ray bend. It's very strange plus with the natural distortion it could be a combination. Just thinking out loud on it. We may need a lens designer to explain this
Thanks Guy. Well I asked one of the best lens designers, namely J. Brian Caldwell, please see post #1.
Many thanks. Which software did you use for post. LR or C1?
To me, except for the first image, the others seem corrected for distortion.
Please advise. Thanks.
p.2 #7 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
k-h.a.w wrote:
Many thanks. Which software did you use for post. LR or C1?
To me, except for the first image, the others seem corrected for distortion.
Please advise. Thanks.
K-H.
I used LR for correction. Since LR doesn't have this lens' profile, I just checked the 12mm for it.
p.2 #10 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
In Capture One Pro a 70% generic pincushion lens distortion correction is applied that straightens out the curvature of the Sunstar.
Here we see how much of the original image area is lost. BTW, applying more distortion correction curves the Sunstar the other way.
p.2 #12 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
LR automatically picks the 12mm profile, which is not so effective when the sunstar is in the corners. I have some that are so extreme, -75 to -100 manual correction straightens them out. We got some great photos with unique effects with the CV 10.
C1 with the generic pincushion at 70% produces similar results.
Some photos from a recent shoot have rays going across 2/3rds of the frame.
p.2 #13 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
I am now curious how the 12/5.6 and 15/4.5 III lenses behave in this situation.
I can investigate the VM 15/4.5 III lens, but unfortunately I don't have the 12/5.6.
Anyone interested in exploring that lens and letting us know? TIA.
p.2 #14 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
RFMP wrote:
LR automatically picks the 12mm profile, which is not so effective when the sunstar is in the corners. I have some that are so extreme, -75 to -100 manual correction straightens them out. We got some great photos with unique effects with the CV 10.
C1 with the generic pincushion at 70% produces similar results.
Some photos from a recent shoot have rays going across 2/3rds of the frame.
Thanks. CS6 behaves similarly to your LR observations.
Could you please display here one of those extreme cases? TIA.
p.2 #17 · Weird Curved Sunstar with Voigtländer 10/5.6 Lens
RFMP wrote:
What is interesting with the CV 10, is when you have really long rays emanating from the corners, the curve is exponential.
Thanks.
Yup, the closer an extremely bright light point source like the sun is located inside a corner the more extreme the curvature gets.
Next question, what happens if that point source is just outside the frame?
Extra distortion correction straightens the sunstar: but the straight lines in the image are now curved.
I'm guessing it's something to do with the flare hitting a curved element in the lens, and projecting a flare image that follows the curve of the element's surface.
But then geometry of the in-focus light and the flare light will be different, so correction for one will affect the other adversely.
But I can't say I think it's a big problem: looking back on some of my images I can see a bit of this, and it doesn't worry me.
