HDRI with ND-Filter on SOME sourceimages

[Guest]

Hello there

I want to create a HDR image with a very wide exposure range. A so called unclipped HDR where also the sun is captured whitout burning out.

I create a range of Images from 1/1 sec to 1/8000 sec, but the 1/8000 sec is still not dark enough for the sun so I add a 16stop ND-Filter to my lens and shoot the sun again from 1/1 sec to 1/2500 sec.

So I have a couple of images with and without an ND-Filter.

The exposure value of each image is calculated from ISO, aperture and shutter speed.

Since aperture is always and f/13 and ISO always at 100 the only value that changes is the shutter speed.

But since the camera (and therefore the meta (exif) data) does not know about if an ND-Filter is attached to the lens Lightroom seems confused by creating the HDR.

How can I tell Lightroom that a ND-Filter was used for an image to not confuse the software.

Before you ask:

- Yeah the full range is needed since the HDRI is later needed in a 3d software to as lightsource.

-  No I can not shoot all images with the ND-Filter since I gonna create a full 360 degree sphere panorama and then the capturing would take way to long if I need to capture the light of a non bright area.

[GoldingD]

Lightroom Classic CC implementation of HDR stitching is at this time limited in capability and annoying pickey on exposure brackets.

I assume some of your shutter speeds with vs without filter might be the same, or the various shots do not come out in exact exposure stop (speed) increments (Offsets)

Try In PS instead, or else a better HDR software might be needed.

Hooefully Adobe will eventually get their.

[Todd Shaner]

Blinky90  wrote

I create a range of Images from 1/1 sec to 1/8000 sec, but the 1/8000 sec is still not dark enough for the sun so I add a 16stop ND-Filter to my lens and shoot the sun again from 1/1 sec to 1/2500 sec.

So I have a couple of images with and without an ND-Filter.

The exposure value of each image is calculated from ISO, aperture and shutter speed.

Since aperture is always and f/13 and ISO always at 100 the only value that changes is the shutter speed.

You could use Lenstagger to change the file's EXIF FNumber data to the "effective aperture" with the 16 stop ND filter.

16 Stop ND Filter = 1.4142 (square root 2) raised to the power 16 x 13 = 256

Effective F Stop = 256 x F13 = F/3328

Not sure how LR and other apps will handle that large of an aperture number, but it should work. I had a similar issue with a Canon PowerShot G9X MKII camera that applies an internal 3 Stop ND filter when the shutter speed exceeds 1/1,250. Fortunately, it can be turned off and is rarely needed!

I suggest backing up the files BEFORE doing anything and try out Lenstagger on a few test files or file copies. Once comfortable with the process you can batch apply the aperture change.

[Todd Shaner]

Just had a chance to test LensTagger with a CR2 file to see if the F Stop 3328 value would work. It does with one small unrelated issue. The F stop value in the Grid or Loupe view 'Infomation' is updated after using 'Read Metadata from File' to pull in the new value. However the Histogram F Stop value does not update, which appears to be a bug. Switching to any other folder and back to the original folder restores the new value in the Histogram. So basically it works and should allow you to use them in your HDR stack.

I tried this with a group of Canon G9X MKII aperture priority shots used for creating a panorama. Two of the image files had the camera's internal ND applied (-3 EV), which I corrected with LensTagger by altering the shutter speed. LR Photo Merge to Panorama brings up the below confirmation panel due to the 3 F Stop EX offset in the two corrected image files. I selected 'No' and the panorama had no exposure issues. It works!