Stay on route and refine the workflow
September 2020: I thought it’s time to make another run of tests by comparing two HDRI’s capturing methods side by side. Since I saw a first HDRI from the Theta-Z1 last year in July, I was intrigued how good this camera could actually be comparing it to a more bulky setup of my Canon 7D and a panohead. I got my hands on another Theta-Z1 for some days, a sunny morning and had both cameras ready.
This comparison has the following objectives:
- account for overall setup time on my test “location”
- required time to shoot and a full HDRI
- prepping and processing time of the RAW images from both cameras
- the image quality of the stitched images
- and what are the limits in dynamic range that can be captured with both cameras
- use the 2014 color checker instead of the 2005 version
The location and the setup
![](https://www.toodee.de/wp-content/uploads/2020/09/IMG_5683-1024x768.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/IMG_5682_xRite.jpg)
The location is quite boring, but good for a test. It is a sunlit parking behind a house, it has car ports that create nice consistent shadow areas and a near clear sky on a sunny Sunday morning.
I placed a small X-Rite color chart on the ground facing the sky and arranged my tripod next to it. For the Theta-Z1 I used the standard app to shoot the RAW-DNG brackets in 1-stop exposures steps with the smallest aperture available (5.6), ISO 100 at 5600 kelvin and the minimum shutter time of 1/25000. I took 18 brackets from which the brightest 6 are not adding much more dynamic range to the HDRI. But I kept them anyway to be merged in PTGui Pro later.
![](https://www.toodee.de/wp-content/uploads/2020/09/DNG_1007_brackets-1024x517.jpg)
The Ricoh Theta app WiFi connection fails from time to time, but overall I was able to shoot one HDRI in around two minutes. The maximum exposure time is 4 seconds. The battery drains fairly quick and to charge or download the images via the USB-C cable the camera needs be be detached each time from the base plate for the tripod. The “weak” battery could be a real problem working all day on a busy set or location.
My Canon 7DMKII set contains a EF-S 10-22 mm lens, a Roundabout nodal point panoramic head and a ND filter. The rest of the settings I have described in the article “2.4.2. More ColorCheckers“. It takes around seven minutes to capture the images for one HDRI, because of the 24 sets of 7 brackets and the longest exposure time of 8 seconds. With the Canon I shot two HDRI’s. One at f-stop 8 and the other at f-stop 22. The first one was clipping in the sun even with the shortest exposure and the second one was underexposed and already quite blurry from the tiny aperture opening.
![](https://www.toodee.de/wp-content/uploads/2020/09/Capture_One_snapshot_brackets_f8_crop-1024x792.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Capture_One_snapshot_brackets_f22_crop-1024x792.jpg)
The stitched HDRI results
Each HDRI was rendered with PTGui Pro 11.28.The Theta-Z1 creates DNG-RAW files and the from the Canon 7D I used the converted TIF files that were created in Capture One 20 from the Canon RAW files.
Camera | Canon 7D f-stop8 | Canon 7D f-stop22 | Ricoh Theta-Z1 |
Shoot time | 7 minutes | 7 minutes | 2 minutes |
File size (RAW) | 3.5 GB | 3.27 GB | 820 MB |
File size (TIFF) | 14.57 GB | 13.24 GB | – |
Resolution | 17.888×8.944 | 17.888×8.944 | 7.414×3.707 |
Balanced Max. Luma Pixel | 25.799 25.774 25.925 | 115.902 114.091 106.155 | 121 122 151 |
sun overexposed | yes | no | yes |
needed EXR format | half float | full float | half float |
usable result | yes | not really | depends |
The rendered HDRI EXR files were loaded into Nuke 12 and balanced to the patch “Neutral 5 (.70D) form the “ACEScg_ColorChecker2014.exr”, which is available here.
![](https://www.toodee.de/wp-content/uploads/2020/09/ColorChecker_after2014_sRGB-1024x576.png)
After the balance step I measured the “Max Luma Pixel” for the R, G and B channels with the Curve Tool in Nuke and also overlaid the patches of the 2014 reference chart over the color chart in each HDRI.
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_colorchart_overlay_Z1_out_rec709-1024x576.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_colorchart_overlay_C7D_f8_out_rec709-1024x576.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_colorchart_overlay_C7D_f22_out_rec709-1024x576.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_1K_crop_Z1_out_rec709-1024x1024.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_1K_crop_C7D_f8_out_rec709-1024x1024.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_1K_crop_C7D_f22_out_rec709-1024x1024.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_1K_sun_crop_Z1_out_rec709-1024x1024.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_1K_sun_crop_C7D_f8_out_rec709-1024x1024.jpg)
![](https://www.toodee.de/wp-content/uploads/2020/09/Balanced_HDRI_1K_sun_crop_C7D_f22_out_rec709-1024x1024.jpg)
The conclusion and pick a winner
Whereas the Color charts look kind of similar, the 1024×1024 pixels crops tells a different story. The first conclusion is that there is always a trade off, but for me the winner is easy to pick. It all depends on factors like required shoot time, the needed resolution and dynamic range. I called the article “Eliminate Variables” and that’s why I pick the Canon 7D f-stop 8 HDRI, although it is far from perfect. It lacks for sure definition in the shadows that you could only get with more brackets or a longer exposure time for the brightest bracket. 7 exposures are not enough here, but without something like Magic Lantern you can’t get more that 7 exposure with this camera in one go.
The Theta-Z1 shoots quicker, but lacks resolution, dynamic range oder an overall image fidelity. There is no easy ND filter solution available that I could test and the minimum aperture of 5.6 and the very short electronic shutter time of 1/25.000 is simply not enough to get enough dynamic range in the sun on a bright day. For image based lighting the sun needs to be modified or painted out and replaced to archive a decent contrast in the shadows.
The Canon 7D f-stop 8 takes longer to shoot one full HDRI, it needs much more processing time and disc space to get a result from PTGui Pro. But it gains with an overall better image quality and dynamic range. Still for a 3D-render it will need more power in the sun. More on this later in the follow-up article.
The Canon 7D HDRI captured with f-stop 22 is not clipping the sun with the shortest exposure, but with only 7 exposures and the strong ND filter the brightest image has too little information so that the result is too noisy and overall underexposed. And its clearly visible in the 1k-crop image comparison that the blue elements in the HDRI don’t even appear blue anymore. It somehow turned magenta.
Canon 7D MKII HDRI captured with a 12mm lens at f8.
Summary
The overall setup time with both cameras are nearly identical when the pano head is properly setup and prepared. The 7 minutes capture time is more critical with moving clouds and even moving shadows edges that can get visible in the stitching later on. It takes 30-45 minutes to render a full HDRI with Capture One and PTGui. I must say I worked in the last year only with some hi-res HDRIs from DSLR’s and comparing them now with a HDRI from a Theta-Z1 feels like a big step back in the overall image quality. In this test the Canon HDRI has nearly 8-stops more dynamic range than the Theta-Z1.
Until I will find a better, quicker and more robust way to get a proper HDRI from bracketed RAW images, I will stick to the combination of CaptureOne and PTGui Pro. The beta version 12 of PTGui Pro looks promising with a lot of new features.
On the next page “Refine and Render” I will setup a Blender 3D scene and render a test with this HDRI.