HDR Crepuscular rays

 I recently purchased the Aurora 2018 HDR software and have found it relatively easy to use with many presets tailored to many different types of imagery.  My most recent eclipse post on this blog shows another sample of its utility.  Here is a mid afternoon cloud shot taken from near the 4-meter telescope on Kitt Peak looking generally west-south-west-ward towards the southwest ridge of telescopes.  The scene greatly benefits from HDR techniques:

The first image is a combine of 5 images taken with my Sigma 17-70mm lens at 17mm focal length with exposures on the short end starting at 1/1250 seconds at f/8 and the longest at 1/200 seconds, all at ISO 100.  I used Aurora's "Realistic Bright" preset which brought out the landscape and helped also show the crepuscular rays coming down from the clouds.

This is the mid exposure (which is also the nominal exposure on this scene) of the 5 HDR images so you can see how dark the landscape is and also how washed out the details in the clouds appear.  The exposure was 1/500 seconds at f/8, ISO 100.

Total Eclipse, take 2 on HDR combines...

I recently installed the Aurora 2018 HDR software on my PC and here are a couple different HDR combines which greatly enhance the detail in the solar corona as well as helping to bring out the detail in the Earthshine-lit lunar surface in some HDR exposed images of the August 21, 2017 total solar eclipse.  The HDR combines use 5 images taken at 2 stop intervals from 1/500 seconds to 1/2 seconds using my Canon 6D with a 0.7x focal reducer on my 8 inch EdgeHD telescope.  The images were taken about 25 seconds before the end of totality when the prominences on the western side of the Sun were mostly uncovered by the Moon.  Once I learn how to use Aurora, I might be dangerous in taking HDR images!

This first image combine is from 5 HDR frames taken at 2 stop intervals about 25 seconds before the end of the total phase of the August 21st total eclipse.  I wanted to show off the prominences on the western side of the sun as well. Not only is there lots of detail in the corona, but the Earthshine-lit lunar surface shows a great deal of detail.

This second image trades some corona brightness for some more detail on the view of the prominences but uses the same 5 images as the first image above.

A Canyon Sunset from Desert View

We watched the sunset during our Grand Canyon trip last month from next to the Watchtower at Desert View near the eastern entrance to the Grand Canyon.  I was hoping for a more colorful sunset, but the nearly completely overcast sky limited the colors present.  Here are a couple HDR combines, the first looking west into the canyon below the main visitors center on the South Rim.  I combined 5 exposures at 1 stop offsets centered on the metered proper exposure.  The shortest exposure which allowed the brightly lit sun to be visible in the sky was 1/45 seconds at f/6.7, ISO 200.  The longest exposure was 1/3 seconds at f/6.7, ISO 200.  All with my 24mm lens and the camera was on a tripod.

This view upriver produced some spectacular colors.  The view of the river in the bottom of the canyon was also quite spectacular.  This HDR combine used 5 exposures from the shortest of 1/30 seconds at f/6.7, ISO 200 to 1/2 seconds at f/6.7, ISO 200 with my 24mm lens on my 70D.

The Mayall 4-meter telescope on Kitt Peak

We had two nights to start the year on the 4-meter Mayall telescope on Kitt Peak in Arizona.  We were lucky to have 2 clear nights with some of the best sub arcsecond seeing for that telescope.  Here are two HDR combines of the same 5 images of the telescope.

The first image is a Fattal combine and displays the colors more vividly.  The 5 images used my 10mm fisheye lens at f/2.8 and ISO 3200.  The shortest exposure was 1/500 seconds and the longest 1/30 seconds with the cameras nominal exposure at 1/125 seconds.

The second image is a Mantiuk '08 combine which displays the view of the 4-meter telescope and the inside of the dome fairly close to what the human eye sees the scene.

Kitt Peak sunset silhouette

I was thinking it would be fun to get the sun setting right behind Kitt Peak, but the location west of Tucson along Kinney Road in Tucson Mountain Park was a bit too far north so that the Sun set on the northern flank of the Coyote Mountains that lie just east of Kitt Peak, near the right edge of this image.  With the harsh sunset lighting, I used some HDR combines of a set of 5 images to get the best range in the image.

This first HDR combine uses the Ashikhmin operator and displays the colors in the sky nearly as I saw them.  The 5 exposures that went into the combine range from 1/3000 sec at f/16, ISO 800 with my 75-300mm telephoto lens at 250mm focal length to 1/180 seconds at f/16, ISO 800.

This HDR combine using the same 5 images mutes the colors with a Mantiuk 06 operator but shows detail in the mountain rainge that is not visible in the more saturated version.

HDR Sunset

I was out playing with my new camera again at sunset tonight.  Here are a couple HDR combines (using auto exposure bracketing in the camera and a sequence of 5 shots and Luminance HDR on my Linux box for the combine)  of the desert landscape looking west into the sunset.  It's amazing how different the combines can be.

 I liked this shot because it has a lot of color saturation.  Most of the foreground detail are only visible in the longest exposure so I was very pleased at how it appears here.  With the bright sun, the shortest exposures that show the halo of sunlight show very little else.  This view is not too far from what my eye saw while composing the shot - the human eye and brain is excellent at being able to see this type of scene.  The shortest exposure was 1/8000 seconds at f/8, ISO 100 using my 24mm f/1.8 lens on my 70D.  The mid exposure was 1/2000 seconds at f/8, ISO 200.  The longest exposure was 1/250 seconds at f/8, ISO 200.  The HDR combine was a fattal operator.

This HDR combine is a Mantiuk '06 combine of the same 5 images as the previous image.  The low saturation almost gives the appearance of there being snow on the ground.

Old Main in HDR

I went for a hike around the University of Arizona campus around sunset and took some HDR exposures of Old Main, the oldest building on campus.  I bracketed 5 exposures from 1/350 seconds at f/8, ISO 400 with my 24mm lens to 1/20 seconds at f/8, ISO 400.  Here is the first exposure, the shortest:

 And here is the last, longest exposure:

Using Luminance HDR under Linux, Here are some of my favorite combines:

This used a Reinhard '05 operator.

This was the most colorful with a Fattal operator.

This final one gave perhaps the best contrast in the sky but was a bit low contrast in the foreground scene using a Mantiuk 06 operator.

Desert HDR experiments

During my hike in the desert along the Encinas trail, I took some images bracketing the nominal exposure.  The following set were done along with a set of shots through an IR filter (see my earlier blog post: IR in the Desert)  I took 5 images centered on the nominal exposure with 1 stop steps for each exposure.  The first image was the nominal exposure which I thought was a little over-exposed.

The first image was exposed with my 50mm f/1.8 lens at 1/90 seconds and f/8, ISO 400.  Exposure times for the other 4 images were 1/350, 1/180, 1/45 and 1/20 seconds.

This HDR image combine used an Ashikhmin operator in Luminance HDR on my Linux box with equation 2 and a levels adjust before saving the image.

This HDR image combine used a Reinhard '05 operator in Luminance HDR with a levels adjust before saving the image.

Lewis Falls

 As we  drove south through Yellowstone National Park, heading for the south entrance, we passed Lewis Lake and then crossed a bridge and saw this waterfall which we weren't expecting, so we pulled into the pullout and I grabbed my camera gear.  It was close to sunset, so exposures were going to be long, so I decided to bracket shots and maybe combine them later with and HDR program.  Using my 24mm lens, I took shots +/- 1 stop around 6 seconds at f/22, ISO 100.  I used ExpoBlending under Linux to do the combine

This is the middle image of the three used in the above HDR combine.  The improvements are not all that obvious in this case, but the next image did well with the HDR combine.

From the same location, I switched to my 10mm fisheye and took three exposures with a 1 stop bracket centered at 1/6 second at f/2.8, ISO 100.

I set up at the north end of the bridge over Lewis River and took an HDR set of exposures with my 75-300mm lens at 90mm focal length, bracketed by 1 stop centered on 5 seconds at f/11, ISO 400.