22 degree halo

A time series of 412 photos was taken during the afternoon on 21 July 2026 using my Fujifilm X-T1 camera and a Meike 6.5mm circular fisheye lens. The first photo was shot at 12:37 PM; the last photo at 12:58 PM.

The camera was mounted on a tripod with the lens facing the zenith. The entire dome of the sky is shown in the circular field of view; the horizon is located around the outer rim of the circle.

21 July 2026 | Fairfax County, Virginia USA

A 22° halo around the Sun is visible high in the sky.

The small halo appears as a white or mostly white luminous ring of 22° radius with the light source (Sun or Moon) at its centre. ... The sky inside the ring is conspicuously darker than the rest of the sky. The halo always has a 22° radius regardless of its position in the sky. Source Credit: 22° halo, International Cloud Atlas, World Meteorological Organization.

Camera Settings

The camera was set for manual exposure and manual focus. The Meike lens features a "clickless" aperture ring. The Aperture was set for the f/8 mark on the aperture ring. The manual focus ring was set near the 3 ft mark. The Shutter Speed was set for 1/4,000 s, the fastest mechanical shutter speed featured on the Fujifilm X-T1. 

The camera was set to record FINE+RAW, in L 3:2 format (4896 x 3264 pixels). A three (3) second interval was used to allow sufficient time for the camera to save the photo files to a memory card.

Panorama Photo

The following panoramic composite image was taken using the "Camera" app on my Apple iPad mini 6, set for "Pano" mode. The iPad was mounted on a tripod located at my usual vantage point on top of a seven-story parking garage.

21 JUl 2026. 1:28 PM. Panoramic view. (14402 x 3877 pixels.)

Notice the low- and middle level cumuliform clouds.

Wind (mph), Weather and Sky Condition

"Wind (mph)," "Weather" and "Sky Cond." are highlighted by red rectangles in the following excerpt from a table of three-day weather observations for KDCA on 21 July 2026, nearest the times when I recorded the time lapse videos and panoramic composite photo.

Source Credit: KDCA | National Weather Service

The preceding table shows the surface wind direction is from the south-southwest. High level cirrostratus clouds (Cs) were streaming across the sky from west to east, as shown in the time lapse video. The difference in wind direction indicates vertical wind shear.

Tech Tips

The camera-lens combo was mounted on a ball head/tripod so that the lens is pointed at the zenith. Notice the green plastic spirit level mounted on the X-T1 hot shoe, used to level the camera body in this orientation.

Camera-lens combo mounted on ball head/tripod.

Apple "QuickTime Player" was used to render 412 JPEG images from the photo set into a time lapse video. The video was edited lightly using Apple "Photos." The post-processed video clip was made into a YouTube movie using "DaVinci Resolve."

Related Resources

• Halo Phenomena | International Cloud Atlas - World Meteorological Organization
• 22° halo | International Cloud Atlas - World Meteorological Organization
• Results for the query "halo" on Walter Sanford's blog

Copyright © 2026 by Walter Sanford. All rights reserved.

Backdoor cold front

For locations in the northern mid-latitudes, weather systems usually move from west to east. Usually, but not always.

A backdoor cold front is a weather boundary that moves south or southwest, bringing cool air from the east or northeast. Unlike typical cold fronts that push west to east, it arrives from an atypical direction—entering through the "back door." Source Credit: Backdoor cold front (Wikipedia).

On 12 July 2026, weather radar showed a backdoor cold front located over the mid-Atlantic United States.

RadarScope (app) animation beginning at 12:00 noon EDT.

The precipitation echoes moving from east-to-west (to the north) and west-to-east (to the south) trace an invisible boundary between different air masses -- that's the "backdoor" cold front!

RadarScope (app) animation beginning at 2:18 PM EDT.

Tech Tips

Set the RadarScope (app) "Radar Frame Count" for 30 frames, the maximum number of frames.

Settings / General / Data / Radar Frame Count

A 30-frame time lapse lasts ~25 to 30 minutes. That's not very long, so I recommend you set the preceding videos to Play in a "Loop."

Click the white "Play" button. When the button turns red, right-click on the video and select "Loop." Then press the "Play" button again and the video will loop over and over. Alternate procedure (for mobile devices): Click the "Settings" button; select "More options" then select "Loop."

Related Resources

• RadarScope app - available for both Apple iOS and Android operating systems
• backdoor cold front - AMS Glossary of Meteorology
• "Backdoor" Cold Front - National Weather Service Glossary
• Search results for "RadarScope app" tag from walter sanford's photoblog (4 posts)

Copyright © 2026 by Walter Sanford. All rights reserved.

Using a Fujifilm X-T1 for time lapsing, revisited

Two time series of photos were taken during the afternoon on 15 June 2026 using my Fujifilm X-T1 camera and a Meike 6.5mm circular fisheye lens. Apple "QuickTime Player" was used to render the JPEG images from each photo set into a time lapse video. Both videos were edited using Apple "Photos." The two video clips were combined to make a movie using "DaVinci Resolve."

The camera was mounted on a tripod with the lens facing the zenith. The entire dome of the sky is shown in the circular field of view; the horizon is located around the outer rim of the circle.

The "Scene 1" time lapse video was created from 432 photos: first image = 1:29 PM; last image = 1:50 PM. The "Scene 2" time lapse video was created from 473 photos: first image = 2:35 PM; last image = 2:58 PM. My GoPro HERO4 Black action camera was used to record a panoramic sky lapse video during a break between "Scene 1" and "Scene 2."

15 June 2026 | Fairfax County, Virginia USA

When I started using the Meike 6.5mm circular fisheye lens for "all sky" time lapsing, I mounted the camera on a tripod with the center column fully extended. The idea was to raise the camera/lens high enough that I could stand by the tripod without appearing in the fisheye photos. As expected, this resulted in camera shake and noticeably "jittery" video. I lowered the center column so there's no extension, making the camera steadier. That's a good thing. The trade-off is now you can see me in some photos at times. I can live with that.

Test Shot

It's very difficult to see the LCD screen of the X-T1 in bright sunlight, so I went to a shady place where I could take a few test shots to be sure exposure was set correctly.

15 JUN 2026 | 1:21 PM | f/8 | 1/3,200 s | ISO 200 | 4896 x 3264 pixels

Camera Settings

The camera was set for manual exposure and manual focus. The Meike lens features a "clickless" aperture ring. The Aperture was set for the f/8 mark on the aperture ring. The manual focus ring was set near the 3 ft mark. The Shutter Speed was set for 1/3,200 s. 

The camera was set to record FINE+RAW, in L 3:2 format (4896 x 3264 pixels). A three (3) second interval was used to allow sufficient time for the camera to save the photo files to a memory card.

Panorama Photo

The following panoramic composite image was taken using the "Camera" app on my Apple iPad mini 6, set for "Pano" mode. The iPad was mounted on a tripod located at my usual vantage point on top of a seven-story parking garage.

15 JUN 2026. 3:17 PM. Panoramic view. (16350 x 3906 pixels.)

Wind (mph), Weather and Sky Condition

"Wind (mph)," "Weather" and "Sky Cond." are highlighted by red rectangles in the following excerpt from a table of three-day weather observations for KDCA on 15 June 2026 nearest the times when I recorded the time lapse videos and panoramic composite photo.

Source Credit: KDCA | National Weather Service

Low-, middle-, and high level clouds were streaming across the sky from the north-northwest to south-southeast.

Tech Tips

Everything You Need to Know About SD Cards by B&H eXplora provides a clear and concise explanation of the numbers and symbols that appear on SD memory cards. Although the article is a good resource it's the kind of information that makes my head feel like it's going to explode! So I just assumed the fastest memory cards I own were incompatible with my older Fujifilm X-T1. Turns out I was wrong.

After reading my blog post entitled Field testing an X-T1 for time lapsing - an after action report my good friend Luis Acosta suggested I try using one of the fastest memory cards I own with my X-T1. I did, and much to my surprise it worked. In fact it works so well I could probably record FINE+RAW files using a two-second interval. So I decided to give the X-T1 another chance for time lapsing. The following photo shows the memory card I'm currently using with my X-T1.

SanDisk 64 GB SDXC memory card.

Sometimes the little things make a big difference. I repurposed the lens cap strap from an old Kodak digital camera (now that's old!) to make a safety tether for the lens cap that covers my Meike 6.5mm circular fisheye lens. It's not elegant yet seems to work well. Also notice the green plastic spirit level mounted on the X-T1 hot shoe. I use it to level the camera body when the lens is pointed at the zenith.

Lens cap tether for Meike 6.5mm circular fisheye lens.

Post update: I forgot to mention "Mr. T," a little trick I learned from Chris Lee (a.k.a., pal2tech) that makes a big difference. For more information watch Fujifilm Shutter Speed Dial (8:20), a YouTube video by Chris.

Finally let's transition to a brief discussion about "DaVinci Resolve." I have learned two hard lessons from my early struggles to get up-to-speed with DaVinci: 1. Always spec the "Project Settings" before you begin editing ("Timeline resolution" most importantly); and 2. DO NOT move or rename media files on your computer after adding them to the timeline.

Related Resources

• Field testing an X-T1 for time lapsing - after action report - a blog post by Walter Sanford
• More Fisheye on the Sky - a blog post by Walter Sanford
• Fisheye on the Sky - a blog post by Walter Sanford

Copyright © 2026 by Walter Sanford. All rights reserved.

Solstice sunset

As a child we learned "the Sun rises in the east and sets in the west," right? Not always. In fact that's true only two days a year -- the equinoxes (March and September).

The Motions of the Sun Simulator was used to show the apparent motion of the Sun across the sky on the June Solstice. Notice the Sun rises along the northeastern horizon and sets along the northwestern horizon. At Washington, D.C. (38.89° North latitude and 77.03° degrees West longitude) the Sun reaches a maximum altitude of 74.7° above the horizon, the highest maximum altitude all year.

"Motions of the Sun Simulator" set for 21 JUN at 38.8 N latitude.

The following animation shows the Sun's apparent path across the sky on the June Solstice, repeated several times.

Firsthand Observations

I used my iPad mini 6 running the "Theodolite" iOS app to take a time series of images during the evening on 21 June 2026, beginning at 8:00 PM and ending at 8:36 PM (sunset) with an interval of five minutes between shots. The camera was mounted on a tripod facing exactly west. Notice how far north of west the Sun sets.

21 JUN 2026 | 8:00 PM | Facing west.

21 JUN 2026 | 8:05 PM | Facing west.

21 JUN 2026 | 8:10 PM Facing west.

21 JUN 2026| 8:15 PM | Facing west.

21 JUN 2026 | 8:20 PM | Facing west.

21 JUN 2026 | 8:25 PM | Facing west.

21 JUN 2026 | 8:30 PM | Facing west.

21 JUN 2026 | 8:36 PM | Facing west.

The exact position of sunset was obscured by both clouds and the tree line to the west of my vantage point, but it's clear enough the Sun set near the trunk of the tallest tree along the horizon.

By the way, I have no idea what the white orb is that appears in the lower-right corner of most of the sunset images. I assume it's a feature of the "Theodolite" app, but I'm not sure.

Related Resource: Theodolite - a blog post by Walter Sanford

Post update: The mysterious white orbs that appear in my "Theodolite" images are "augmented reality (AR) markers to show the position of the Sun." According to the developer, the fact that the Sun, as shown in my photos, isn't aligned with the AR markers indicates the compass on my iPad mini 6 was a little off. (Source Credit: "Thoedolite" app developer.)

Google AI says "Check if your iPad case has magnetic closures ... , and try removing the case temporarily to see if your accuracy improves." The Apple case I use with my iPad does feature magnetic closures so I will try removing the case. Although that might help reduce magnetic interference, it might not eliminate the problem because the iPad itself has a built-in magnet that is used to attach an Apple Pencil.

All of that being said, the amateur scientist in me thinks it's also possible the "Theodolite" AR might be a little off, especially since I calibrated the Apple iPad compass before using "Theodolite" to photograph the solstice sunset. I'm just saying, multivariate analysis isn't easy.

Copyright © 2026 by Walter Sanford. All rights reserved.

GoPro Panoramic Sky Lapse

The following panoramic time lapse video shows the sky above Fairfax County, Virginia USA on 15 June 2026. The video was recorded using my GoPro HERO4 Black action camera mounted on an inexpensive mechanical one-hour kitchen timer. The camera was set for "Video" mode / "Time Lapse Video" submode at a resolution of 4K and an interval of two (2) seconds.

15 June 2026 | Fairfax County, Virginia USA

The following panoramic composite image was taken using the "Camera" app on my Apple iPad mini 6, set for "Pano" mode.

15 JUN 2026. 3:15 PM. Panoramic view. (16080 x 3900 pixels.)

Sometimes I like my "misfires" as much as the wider panoramic composite images such as the one shown above.

15 JUN 2026. 3:18 PM.

Related Resources: Blog posts with label "GoPro."

Copyright © 2026 by Walter Sanford. All rights reserved.

Theodolite

Theodolite is an award-winning app for Apple iOS that has many applications for my sky watching activities. Wait, what is a "theodolite?"

A surveyor's instrument for measuring horizontal and usually also vertical angles. Source credit: Merriam-Webster (dictionary).

Tracking cloud motion

I used the "Theodolite" app to determine the position of the four cardinal points for my location. That enables me to know the direction clouds are moving across the sky.

15 JUN 2026 | Facing north.

15 JUN 2026 | Facing east.

15 JUN 2026 | Facing south.

OK, I was a little off-center for the direction "south."

15 JUN 2026 | Facing west.

Tracking weather satellites

Radio signals from polar orbiting weather satellites can be received using free software and relatively inexpensive hardware including an RTL-SDR and V-dipole antenna. For best results the V-dipole antenna should be oriented north-south, with the open end of the "V" facing south. For more information, see the following article: Simple NOAA/Meteor Weather Satellite Antenna: A 137 MHz V-Dipole.

Oh by the way, of course I used the "Theodolite" app to determine the direction of north and south relative to the position of my portable rig for reception of weather satellite radio signals.

Tracking daily- and annual cycles in the Sun's apparent path across the sky

The June Solstice will occur at 8:25 UTC on 21 June 2026 (4:25 a.m. EDT), according to the Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion page, Astronomical Applications Department, U.S. Naval Observatory.

The Motions of the Sun Simulator can be used to explore the apparent motion of the Sun across the sky on the June Solstice. The following screenshot shows the simulator configured for 21 June at 12 noon. Be sure to set the "animation mode" for "continuous" and "loop day," as shown in the following graphic.

"Motions of the Sun Simulator" set for 21 JUN at 38.8 N latitude.

Notice the Sun rises along the northeastern horizon and sets along the northwestern horizon. At Washington, D.C. (38.89° North latitude and 77.03° degrees West longitude) the Sun reaches a maximum altitude of 74.7° above the horizon, the highest maximum altitude all year. "This maximum angle occurs precisely at local solar noon, which usually happens around 1:00 PM EDT due to the Earth's axial tilt of 23.5° and daylight saving time adjustments." Source Credit: Google AI.

Also notice the odd-looking figure eight that is shown in red on the preceding screenshot. It's called an analemma. The crest of the figure eight shows the Sun's maximum northern latitude on the June Solstice.

Many years ago I used the "Theodolite" app to show the direction of sunrise on the March Equinox. You might want to do something similar for either sunrise or sunset on the June Solstice.

20 MAR 2011 | 7:12 a.m. | Facing east.

Tech Tips

The following settings were selected under "PREFS" (upper-left corner) / "Camera Options...": "Screenshot"; "Photo Size" <100%>; and "Also Save Regular Image" <Yes>. 

The "Theodolite" app isn't available for devices running the Android OS. According to Google AI, the top-rated comparable app is "Sololocator - GPS Field Camera" ($0.99), available from Google Play.

Related Resources

• Theodolite Augmented Reality Navigation Viewfinder for iPhone and iPad
• Theodolite / Theodolite HD User Manual
• Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion - Astronomical Applications Department, U.S. Naval Observatory
• Motions of the Sun Simulator - University of Nebraska-Lincoln Department of Physics and Astronomy
• Position of the Sun on the horizon at sunrise - University of Nebraska-Lincoln
• Equinox sunrise - walter sanford's photoblog
• Sunrise Positions in Washington, D.C. - a post from my old Web server, rescued from the Wayback Machine Internet Archive, featuring a time series of photos by Dr. Robert Weinbeck, American Meteorological Society

Copyright © 2026 by Walter Sanford. All rights reserved.

Field testing the Viltrox DC-A1 camera monitor

The following YouTube video includes three time lapse video clips that show the sky over Fairfax County, Virginia USA during the afternoon on 09 June 2026. Three photo sets were captured using a Fujifilm X-T3, 18-55mm kit lens, and Viltrox DC-A1 camera monitor. Each photo set was rendered to video using Apple "QuickTime Player"; each movie clip was edited using Apple "Photos." The final video was created using DaVinci Resolve.

09 June 2026 | Fairfax County, Virginia USA

The sky was overcast to mostly cloudy, covered by high level cirroform clouds at 25,000 feet. Notice the cirrocumulus clouds visible in all three video clips.

Source Credit: KDCA | National Weather Service.

Tech Tips

A "Viltrox DC-A1 2800 Nits 7-Inch Camera Monitor" enabled me to see the camera display clearly, even in direct afternoon sunlight. The monitor sells for $278.00 MSRP; I bought it on sale for $236.30 from B&H Photo. The DC-A1 comes with a snap-on/off Sun Hood, L-series/NP-F550 battery, HDMI Type-A cable, HDMI Type-A to Mini-HDMI cable, and USB-C power cable (USB-C to USB-A), among other accessories.

My Fujifilm X-T3 connects to the Viltrox DC-A1 via a micro-HDMI to full-size HDMI cable, not included with the monitor. (My Fujifilm X-T1 features a mini-HDMI connector, but HDMI Output works only during Playback.)

The Viltrox DC-A1 can be used to show the display of my Apple iPad mini 6 by connecting the iPad to a CalDigit SOHO Dock via a USB-C cable, then connecting the SOHO to the Viltrox DC-A1 via a full-size HDMI cable. Although the display size of the Apple iPad mini and Viltrox DC-A1 is similar, the DC-A1 is much brighter than the iPad (as shown below).

It's all about "nits."

"nits" is a quantitative measure of screen brightness. The following bulleted list shows the brightness (in nits) for many of the cameras and devices I own.

• Viltrox DC-A1 Camera Monitor = 2800 nits
• Apple iPad mini 6 = 500 nits
• Samsung Galaxy Tab A9+ = 480 nits
• Fujifilm X-T3 = estimated 300-400 nits
• Fujifilm X-T1 = no official rating (seems to be dimmer than X-T3)
• Panasonic DMC-FZ300 = estimated 400-500 nits
• Canon EOS 5D Mark II = estimated 350-400 nits
• GoPro HERO4 Black action camera = There is no viewfinder screen on the back of the HERO4 Black, only a small "Camera Status Screen" on the front of the camera. (GoPro "Quik" app runs on Apple iPad mini 6, therefore 500 nits.)
• Skyflow (iOS app) = Runs on Apple iPad mini 6, therefore 500 nits.

In contrast with the Viltrox DC-A1, the highly rated Atomos Ninja 5.2" 4K HDMI Recording Monitor has a smaller screen, isn't as bright (1,000 nits), and sells for a higher price ($589.00 MSRP). Yes, the Atomos can record video, but so can my cameras.

So why don't camera manufacturers make cameras with brighter LCDs? My best guess is it's all about optimizing camera battery life. The Viltrox DC-A1 battery is much bigger than most camera batteries and it still drains quickly. Very quickly. And so would camera batteries if they were used to power brighter screens.

Related Resources: Blog posts with label "Fujifilm X-T3" and "Fujifilm X-T1."

Copyright © 2026 by Walter Sanford. All rights reserved.