Am 04.09.2023 um 00:27 schrieb 'Star QualityVideo' via PTGui Support:
> Here is a link to the images. TY
I played a bit with your images, but got no very good result. I Loaded
all images in PTGui, agreed to link bracketed images and passed Align
Images. Alignment was good except the ND filter images. I then set ISO
32768 for all but the ND ones, which got ISO 1. Then I dragged the ND
group on Image 1 to have it share the alignment.
There was a distinct border between the ND group and the rest around the
sun. This has three reasons:
1. In the darkest non-ND image there is a horizontal streak right and
left of the sun, which isn't present in the ND images. Since this streak
is brighter than the sun star, which causes a visible border.
2. The ND filter density is not 15, it's most likely 16. I tried to
manually set ISO values, such that the border visibility minimizes and
reached that at ISO 64000, which is roughly 2^16. The border at the
streak is still visible, though.
3. The ND filter has a slight purple tint. This should be corrected
during raw development. PTGui can't do that.
(Project file attached)
> I can regroup the ND filter set after alignment but the final HDRI is very
> dark when I add the ND filter set back to the group.
That's quite normal, if you output an HDR format. PTGui scales the
output such that 1.0 corresponds to white in the middle exposure of your
bracketed sets. As it is a floating point format, there is still no
May I ask what your goal is? Do you shoot for image based lighting? If
not, using that many brackets is superfluous. If yes, it might be better
to not use a ND filter either, but more standard brackets instead. You
can do composite bracketing by f.e. also changing ISO and aperture. Or
even simpler: Since only the sun exceeds the dynamic range of the non-ND
shots, paint the sun with the desired brightness in your image editor.
BTW.: The sensor of your camera already captures more than 14 EV. With
bracketing 12 EV you get a total of 26 EV dynamic range, which should be
enough for all HDR needs. Not even the Spherocam HDR (used for a lot of
Hollywood productions) has more...