Fog

FOG

`The weather is like the government, always in the wrong’

Jerome k Jerome

Shetland weather is very mixed and it is said that you can have four types of weather in the same day and this is true. In summer when the temperature rises and meets old air it causes fog, very dense in places.

The Haar – or sea fog rolls in and cloaks hillsides and crofts and makes things mysterious. Fog is also known as `Stumpa’ in Shetland. The most common is Advection fog which is caused by a warm air mass crossing a cooler surface- often the sea, in which case the heat is transferred downwards from the air. This reduces the air temperature to its dew point, producing saturation then fog.

The difference between Advection and radiation fog is the role played by air movement in its formation. The term `Advection’ is used almost exclusively in meteorology and oceanography normally referring to the horizontal motion that transports some property of fluid. Advection refers to the amount of heat transported by the wind or ocean currents.

Advection fog is commonly found in areas such as Shetland, especially on the east side as warm air is cooled by the sea surface, this is known as sea fog – Haar, it occurs often in spring and early summer when the sea temperature is recovering from its lowest.

Advection fog is always moving and even winds of 30 knots may not move it, however a stronger wind will lift the fog to form extensive stratisform cloud.

We love to complain when the weather is poor or visibility reduced by fog but we can appreciate the good weather when it comes.

As a photographer I love to find the edge of the fog where the sun meets the dense mass creating a great contrast of light. Below is a photograph of Channerwick Bay in the south mainland, the bank of fog holding its position for a few minutes before enveloping the tractor beach and fields.

Here is an interesting fact:

The tiny water droplets that make up fog are so small that it would take seven thousand million of them to make a single tablespoonful of water

Orion

Only had two clear skies since moving up to Shetland, but the stars were amazing with very little light pollution. Unfortunately it was too windy for photos and now the days are long with little darkness so it may be a while before i can get any more star photos. I will be adding more sky photos soon. For now its good to remember Orion.

Anyone looking up at the night sky to the south cannot fail to see the Orion constellation. It is recognised by the bright stars of Rigel and Betelgeuse top and bottom. The three stars in the middle are know as Orion's belt and looking closely at the three stars  the Orion Nebula can be seen lower down on what is named as Orion's sword.

Orion is most visible from January - March in the northern hemisphere, but May - July it cannot be seen as it appears in daylight hours.




Orion can be used to locate other stars, by extending the belt south Sirius can be found and like wise north Aldebaran can be located.

The three stars in the belt are

• Alnitak which is a triple star 736 light years away
• Alnilam is a large blue super giant the 30th brightest star in the sky
• Mintaka is 916 light years away and is the faintest of the three stars

Orion Nebula (Messier 42) is possibly the first deep sky object people want to photograph, after all its easy to find and can be seen by the naked eye. The Trapezium is a cluster of quadruple star system and  has many new born stars together with luminous gases and dust make a great object to photograph. It is amazing to find that it is 1,344 light years away and is thought to contain over 1,000 young stars and 700 other stars in various phases. 

The first ever photo of Orion Nebula was back in September 1880 when Henry Draper used an 11 inch refractor telescope to take a 51 minute exposure. It was also the first object that the Hubble telescope observed in 1993

the above Nebula photos are 17 images @ 50 seconds guided then combined.

Reducing Light Pollution

                                                           New light pollution map of Europe

At least most of Shetland, apart from Lerwick, Scalloway and Sullom are reasonably dark sites. I know I keep on about this but in Sheffield light pollution is a major problem, even in the depths of the Peak District you have Manchester at one side, Sheffield at the other.

This makes it impossible to take an exposure of more than 40 seconds otherwise you can see an orange glow appear in the image. Perhaps a light pollution filter might help, or in my case make a drastic move to Shetland where this is less of a problem.

                                       Unprocessed Photo except for noise reduction at ISO 1600


To see the Milky Way and other constellations you need to view from a dark area otherwise the light drowns out the stars. This is also the case when a full moon appears. I have been surprise that many people think that the moon is needed to provide a light in the sky to illuminate the stars, sorry but this is far from the truth.

People often say that you need to be more than 100 miles from a city to benefit, some chance in the UK. One thing to help is to shoot in RAW and then adjust the white balance after, but those shooting in jpeg should set for daylight white balance. Using an Astronomik CLS Filter will reduce the light pollution and bring back the colour of the stars. Don't forget the optimum time for photography is around 2 am when most people have turned their lights off and gone to bed.

While you are out waiting for a long exposure you need something to do, so when not some light painting

                                                                                                                                                      It's me !!!

Massive Meteor shower due

Make sure May 24, 2014, is circled on your sky watching calendars. On that date, we might experience the most dramatic display of "shooting stars" in more than a decade.

According to predictions, a little-known comet will pass perihelion in early May of 2014 and, two weeks later, sandblast Earth with dust particles spread along its orbit.

NASA / JPL / Horizons

The source of all this buzz is a little-known periodic comet called 209P/LINEAR. Discovered by an automated sky survey in 2004, it follows a looping but relatively tight path that carries it just inside Earth's orbit every 5.04 years. According to dynamicist Syuichi Nakano, Comet 209P/LINEAR's next perihelion occurs on May 6, 2014, at a point 0.969 astronomical unit from the Sun and with Earth not far away. 

Just 18 days later, we should cross through dozens of particle streams shed during past orbits. The predictions are still rough, but three different models suggest the sky show could be spectacular. "All the trails ejected between 1803 and 1924 cross Earth's path in May 2014," notes Jérémie Vaubaillon (IMCEE, France). "As a consequence, this shower might as well be a storm," with the potential to see more than 1,000 meteors per hour under ideal conditions.

That's the same conclusion reached by Russian meteor sleuth Mikhail Maslov, who thinks at least 100 to 400 meteors — and quite possibly many more — should rain down per hour. But he cautions that Comet 209P/LINEAR is small and hasn't been observed much. Moreover, outbursts of meteors linked to this comet haven't been noted in the past.

The potential for a strong showing in 2014 was first pointed out by meteor specialists Esko Lyytinen and Peter Jenniskens, but detailed calculations by Vaubaillon and Maslov have heightened the anticipation.

Although darkness in Shetland will be at a premium at that time of year its worth staying up to see this shower

Moon Phases

The moon always shows the same face to the earth and craters can be seen on the surface. It is the second most luminous planets in the solar system after the sun. Back in 1967 I was at school and witnessed the moon landings, which captured everyone's imagination. there are some that don't believe that the Americans landed at all . the footprints will last for many hundreds of years because there is no wind and no atmosphere to destroy them.

When I look up at the sky at night and see the large searchlight of the moon shining down i cannot fail to be moved. It is approx 239,000 miles from earth yet we seem to be closely connected , i know that the moon is likely to be a part of our planet having been struck by a large meteor which broke a chunk from the earth which eventually became the moon as we know it.

The large featureless plains that can be seen by the naked eye are called Maris or seas, these are really vast solidified pools of lava. These seas cover 31% of the surface on the near side of the moon, on the far side these only cover 2% of the surface.

The light coloured regions are know as the highlands as they are higher than the seas, these have been studied and have been found to be 4.4 million years old.

Craters form a large part of the surface and at the last count there is over 300,000 craters over 1 km in length .

A few days after new moon, when there is just a very slim crescent, you can sometimes see earth shine on the unilluminated portion of the moon .Earth shine caused by sunlight being reflected off the earth and falling onto the moon

                                                                                                                                                          Photos showing earth shine

When photographing the moon make sure that you remove all filters otherwise you will get a reflection as shown the the photo below

stop moving please

In the last Blog i talked about increasing the amount of night photography time.This one is about a different type of time. If you have ever taken a night photo you will know that the stars move (really its the earth that's moving) and cause streaks so you have to calculate the exposure time based on the lens and camera that are used. Often the calculation is based on the 600 or 500 Rule which i think is better for more rounded starts.

                                                                                                                                                                  That's unless you want a star trail effect as above

Shutter Speed Using the 500 or 600 Rule

Use this table to help you calculate the maximum shutter speed you can use before you’ll start getting noticeable star trails in your nightscape photos.

Use the 600 rule for longer exposures and web images where slight trailing won’t be noticeable, or

Use the 500 rule if you’re more conservative or plan to print your images at 30” or higher.

                      1.5x Crop Sensor                   1.6x Crop Sensor                  Full Frame

                               NIKON                             CANON

Focal Length 500 rule 600 rule                  500 rule 600 rule             500 rule 600 rule

8 mm                42 s     50 s                            39 s        47 s                       63 s        75 s

14 mm              24 s     29 s                            22 s        27 s                       36 s        43 s

17 mm              19 s     23 s                            18 s        22 s                       29 s        35 s

24 mm              14 s     17 s                            13 s        16 s                       21 s        25 s

35 mm                9 s     11 s                              9 s        11 s                       14 s        17 s

50 mm                7 s      8 s                               6 s        7.5 s                      10 s        12 s

70 mm                5 s      6 s                               4 s         5 s                          7 s          9 s

For custom focal lengths, simply divide 500 or 600 by the focal length of your lens.

Example, for a 20 mm lens: 600 / 20 = 30 seconds on full frame, or 600 / (20*1.6) = 19 seconds on a Canon crop camera or 600 / (20*1.5) = 20 seconds on a Nikon/Sony crop camera.

  

For a 2 x crop sensor (bridge or 4/3rd camera)

            500 rule

14 mm  17 s

20 mm  12.5s

30 mm    8s                          

45 mm   5s

Finally

At last some dry weather with clear skies. On Tuesday it cleared late on but I was out giving a talk on Shetland so wouldn't have  been able to do any night photography. On Wednesday night we had already made plans so it was down to Thursday and luckily it was a good clear night but very cold, down to -4 degrees.

When i arrived up at Ringinglow near Sheffield it was just light so I set up asap and thought I was in a quiet spot until around 50 cyclists past in 3 groups, followed by a few cars which lit up the area I was working in. So not a dark site but as I have mentioned before we don't have any true dark site around here

Orion nebula (Red spot)

On Thursday I was lucky enough to see the aurora which was a surprise as i had not received any notification. Seeing the photos the next morning from Shetland you can understand why Sheffield had a glimpse for around 30 seconds. The photos coming out of Shetland were incredible with some fantastic reds and greens, wish we had been there. The aurora activity is only ever 12 years or so with 2014 being the best one, although some activity can be seen at other times.