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Noctilucent Clouds

Just when you thought you could put the cameras away after chasing the Northern lights through the winter the season for hunting the Noctilucent clouds is almost upon us again. This page will be updated as and when I manage to capture some NLC images for this year.

2019 NLC Daisy Wheel
http://spaceweather.com/DAISY_PICS/current_daisy.png

Noctilucent clouds or NLCs are the jewels in the twilight summer skies, they are also called Polar Mesospheric Clouds or PMCs. For a month or so before and after the Summer Solstice, which is June 20th in 2016, they can shine and dance brightly in the rich blue background of the twilight and dawn skies.

It is only during this short period that the very high Noctilucent clouds can form just below the mesospause layer of the atmosphere approximately 80-85km above us. They require temperatures below -123c which only occur at these high altitudes around the summer solstice period and are created from microscopic particles surrounded by ice crystals which scatter the sunlight. This website provides details of the daily temperatures in the mesopause layer which might aid in forecasting the appearance of the NLCs.

Because of their very high altitude they are the only clouds illuminated by the sun when it is at least 6 degrees below the horizon (approximately 40 minutes after sunset or before sunrise). When the sun reaches 16 degrees below the horizon (about 2 1/2 hours after sunset or before sunrise) the clouds will not be illuminated and they disappear into the night sky waiting to be reborn by the predawn light of sunrise.

They are commonly confused with high white Cirrus cloud which is still illuminated by the sun shortly after sunset or before sunrise or by the moon against a dark sky, but on a moonless night with the sun more than 6 degrees below the horizon you are probably seeing the white or bluish white NLCs.

To view the NLCs you need nothing other than patience, clear skies with little or no light pollution, the right atmospheric conditions and a clear view to the northern horizon. They appear in the Northwest to Northeast direction above the sun’s position below the horizon. Before midnight they are in the Northwest and as the night progresses drift further to the North and Northeast.

To photograph the Noctilucent clouds I would recommend a decent DSLR but a good bridge camera can also capture them. Fast wide angle lenses, with an aperture of f/2.8, will allow you to use a relatively fast shutter speed of around 10-15 seconds. Longer exposures will tend to blur the fine detail in the clouds as they move across the sky. If you use telephoto lenses to capture the very fine detail in the clouds then the exposure times will need to be reduced to a few seconds to avoid motion blur spoiling your photographs.

A tripod, or a good solid wall, is essential to support the camera during the long exposures and a remote intervalometer is ideal to minimise any camera movement. Manually focusing on a star and then turning off the autofocus function will ensure the lens remains focused on the clouds rather than hunting for the correct focus point and manual exposure, or exposure compensation, is necessary  to avoid overexposing the surprising bright NLCs.

Some beautiful still photographs can be taken and if you have the time then taking a lot of images for a timelapse can be very rewarding as you will see the structure of the Noctilucent clouds change as they flow and ebb across the night sky.

If you are very lucky you might catch the NLCs and the Northern lights in the same evening. The timelapse below was captured on the 23rd of June 2015 and shows the Northern lights and Noctilucent clouds from Cemlyn bay on Anglesey.

For more information and scientific details of NLCs I would recommend visiting the Atmospheric Optics and NLCNet websites and the website of the NightSkyHunter for a fascinating insight into the classification of the NLC structures. Spaceweather.com also get some beautiful NLC images when the season kicks off.

The countdown has begun for the new season. Good luck and good hunting !

St Mary de Crypt

Photographs and 360 panoramas of St Mary de Crypt church in Gloucester


Cheltenham Camera Club

Photographs from the Cheltenham Camera Club


Tewkesbury Abbey

This is a small collection of photographs and a 360 degree digital tour which will grow over time as I revisit the Tewkesbury Abbey. If you wish to read more about the Tewkesbury Abbey I would recommend visiting the official website

Tradition, originating in the desire to account for the name of the town, would assign the foundation of a cell or chapel to Theoc, or in Latin form Theocus, in or about 655. In support of this theory Camden and others assert that it was called in Anglo-Saxon times Theocsburg or Theotisbyrg. Others would derive the name from the Greek “Theotokos,” as the Church is dedicated to St. Mary, and others again refer us back to a very early name, Etocisceu—Latinised as Etocessa. In Domesday Book the town is called Teodechesberie, and throughout the Chronicles of the Abbey is called Theokusburia.

The Chronicles of the Abbey tell us that the first monastery at Tewkesbury was built by two Saxon nobles, Oddo and Doddo, in or about the year 715, a time when Mercia was flourishing under Ethelred, and later, under Kenred and Ethelbald. It was dedicated to the Virgin Mary, and endowed with the manor of Stanway and other lands for the support of the Benedictine monks who, under a Prior, were there installed. Oddo and Doddo died soon afterwards, and were buried in the abbey church of Pershore.


Race of Remembrance 2018

The 2018 Race of Remembrance event (#RoR2018) takes place over the weekend of the 9-11th November on the #Tracmon #Anglesey circuit and is hosted by Mission Motorsport

This page has images from the event which are freely available to anyone who wishes to keep a memory of the event or make a print. The on-line images are sized and optimised for use on social media (right click the image and select save image as..), if they are used I would ask that a credit be given.

There are many images from the Race of Remembrance weekend so grab a coffee, or three, and get comfy 🙂 #RoR2018.

If you would like a print file then please e-mail me at kevin@photosbykev.com quoting the number of the image(s) and I will send you the image files that you can print locally. No catch, no charge, just my way of supporting the event. If you wish to give a small donation to support Help for Heroes then please use Mission Motorsport.


Friday 10th – practise sessions (24 images)


Friday 10th – qualifying session (175 images)


Saturday 10th – morning practise sessions (80 images)


Saturday 10th – Supercar Saturday (150 images)


Saturday 10th – The Endurance race

part 1 in very damp conditions (159 images)


Sunday 11th – The Endurance race

part 2 (98 images)

Photogrammetry – baby steps


The Abbot Malvern alias Parker monument

 

The Sarah Morley memorial at Gloucester cathedral (reduced to 10%)

3D model of the Sarah Morley memorial
by Photosbykev on Sketchfab

a print screen showing the full detail of the 3D model

The Cloister fan vaulting at Gloucester cathedral (reduced to 10%)

 

Part of the Gloucester cathedral cloister. 150 images shot on a Canon 5D4 and 50mm lens

Part of the Cloister in Gloucester Cathedral
by Photosbykev on Sketchfab

 

First ‘proper’ attempt at a small 3D model (approx 200mm in diameter) – 23 DSLR images were used to capture this skull carved into a gravestone. The images were processed with 3DF Zephyr lite software produced by the company 3DFlow.

 

RTI Imaging – baby steps

First attempt using a RTI dome populated with 6 x 3 watt daylight LEDs controlled by a custom control box

without processing the image above is a typical record of the subject


My first attempt at RTI, that’s Reflectance Transformation Imaging to you and me 🙂 . I drifted into this type of photography after shooting graffiti at Gloucester cathedral and quickly realised that normal photographic techniques can struggle to bring out all the detail.

Using directional lighting placed at a low angle to throw a strong shadow into the dips and bumps of graffiti craved into stone gives some impression of what is there.

The RTI technique uses a single light source to take multiple photographs, typically 50 or more, with the light source being moved all around the subject during the capture session.

For my 1st attempt at RTI I used a carving in Welsh slate of a Draig, the Welsh Dragon. The sculpture was commissioned for my home several years ago but seemed ideal as a test subject.


1st Baby steps – for this test I was using:

  1. A Canon 5D4 and 24-70mm lens set at 47mm focal length with the target approximately 500mm from the camera and the diagonal coverage of the target was 400mm.
  2. A Sirui tripod with the camera suspended off an inverted centre column.
  3. For lighting I used a Godox AD200 flash head and a laser range finder mounted on a common bracket which I can mount onto a second tripod.
  4. A Phottix wireless camera trigger.
  5. The X-rite ColorChecker Passport Photo calibration card.
  6. A 10mm Silicon Nitride ball bearing and a 25mm Obsidian ball.

Some initial thoughts on the image capture process:

  1. Never underestimate the shadow being thrown by the light sphere when illuminated at 15 degrees. Check it with a test image to ensure the shadow doesn’t encroach on the subject. 
  2. Don’t frame the subject too tightly, leave room for the light sphere and check the shadow again. For info, the length of the shadow is 4 times the height of the light sphere at 15 degrees, it is long!
  3. The 10mm ball bearing only covered 160 pixels on the image, the recommended diameter should be around 250 pixels. The sequence worked but I suspect it was marginal. This is the blended light sphere image the RTIbuilder software produced and shows the highlights created by each flash position. It’s nowhere near perfect but adequate for this first test.
The blended Light sphere

4. I used the X-rite ColourChecker Passport Photo calibration chart to ensure my colour and exposure are as good as I can make them. The brightest image will always be when the flashgun is nearest to the surface normal so check the exposure at 65 degrees and avoid blowing out the highlights.

The off white square next to the pure white square should be used to set the white balance and to set the optimum exposure in Lightroom. The RGB value for this square should 200,200,200, in Lightroom this is approximately 90%, 90%, 90%

5. The black obsidian spheres are relatively cheap but the surface is fairly soft and easily marked, I would recommend buying the more expensive Silicon Nitride ball bearings which are very hard and the surface finish is excellent.

6. The distance from the flashgun to the subject should be 3-4 times the diagonal of the image. I used a laser rangefinder mounted to the side of the flashgun to set the distance and the angle of the flashgun.

7. It’s important to ensure that the camera does not record any of the subject due to the ambient light, so use a low iso (100) and small aperture (f11) and set the shutter speed to your highest sync speed, I used 1/160 second. It is not recommended  to use a smaller aperture because of diffraction, this optical effect causes the image to be softer even though there is an increase in depth of field.


2nd Baby steps – for this test I was using:

a dull 2 pence coin captured with a Canon 5D4 and Canon 100mm macro lens

 

For further information, software and guidance on the capture and image processing the Cultural Heritage Imaging website is well worth a visit.