Upton Broad and Marshes


Image of the Day - Mute Swan on the nest
Note: the feathers on the head and neck are stained orange-brown by iron and tannins in the water


Having walked around the edge of the Marsh on my previous walk and; been suitably impressed by the host of wetland plants, I was inspired to devote a day to exploring the Marsh properly. 

Looking at the map there didn't seem to be any footpaths, but fortunately after a quick bit of surfing I located a site with details of permissive paths through the marshes. You can use this or my track on EveryTrail below. I strongly recomend using my GPS trails as some of the paths are indistinct and some are very close to the edge of treacherous 'quaking marsh' - at least I can guarantee that my trail avoids this area. (You may be lucky enough to find a Norfolk Wildlife Trust leaflet at the car park but this shows paths through the woods only, and keeps well away from the Broad and Marshes).
one of the many dykes in the wood


Nesting Mute Swan

Upton Broad from a viewing platform


Upton Broad and Marshes at EveryTrail

A walk along the River Bure

Inspiration - Thurne Dyke Drainage Mill
Following a visit to Thurne Dyke Drainage Mill (above) earlier this year I was inspired to explore the area more - esp. as the map indicated a large number of mills along this stretch of river.

Palmer's Drainage Mill
Starting from the small car park at Upton Dyke walk through the busy boatyard and you are almost immediately faced with Palmers hollow post mill - the only remaining windpump of its type. Its hard to imagine how such a small fragile looking structure has survived for so long.

Clippesby Mill
On leaving Upton Dyke you are immediately faced by two, unfortunately, derilict mills. Oby to the left and Clippesby to the right.

Oby Mill
Continuing along the path you soon come along side the imposing and quite Dickensian Upton Black Mill
Upton Black Mill
But in the distance are the more cheerful (and inspirational) Thurne Dyke and St Benet's Level Drainage Mills - they are unfortunately the only mills on this stretch of the River open to visitors (and with sails in tact). This strech of the river is also the busiest - with craft coming on to the Bure from the nearby South Walsham Broad.
Thurne Dyke Drainage Mill
St Benet's Level Drainage Mill
St Benet's Level Drainage Mill
Sailing on Thurne Mouth and heading for South Walsham Broad
Lonely South Walsham Drainage Pump
St Benet's Abbey
From St Benet's Abbey the path heads for South Walsham and then turns to border Upton Marshes - the subject of my next post.

River Bure Walk from Upton Dyke at EveryTrail

Blickling Park and the Upper Bure Valley

Preferring the hills and mountains of the Peaks and Lake District or the Dales of Yorkshire, this walk is not one that I expected to enjoy that much. It was just going to be one of those 'weekend' strolls through the flat Norfolk countryside. But no! After repeating the walk a third time in 2 weeks I felt the need to share it, both here and on EveryTrail.

Of course it helped that each time I did the walk, the weather was glorious and being Spring there were lots of flowers and much bird activity along the way. Also..... it was mid-week so I had the whole walk to myself. The solitude was bliss - despite the frequent 'near heart attacks' I experienced, each time I disturbed a ground feeding Pheasant!!!

The walk starts at the Blickling Hall National Trust Car Park. Regardless of which exit you take turn left and follow the road until you reach the gates of the park.

The Ancient Turnstile at the Park Gates
Beyond the gates - thru the ancient turnstile on the right - bear left where the track divides and take a few moments to reflect on Humphrey Repton's carefully sculptured landscape. Then on to the Great Wood where recently there has been much logging activity.

The omnipresent Barn Owl
The first time I walked along this track a Barn Owl swooped down and flew directly in front of me and down the track. That experience endeared me to this walk and immediately raised my spirits.

At the end of the track there is another (small and less well used) car park. Leave it and turn left along a very quiet single track country lane towards Itteringham.

The second time I did this walk I witnessed the Barn Owl make a kill by the side of the lane. I stopped in my tracks, but he was aware of my presence and after completing the kill he flew off into the nearby woods to enjoy the fruits of his labour. Again his presence lifted my spirits.

Just before the road junction at Itteringham Common turn to the right at a signposted footpath. It may be a bit muddy here but not for long. Cross the dyke and river by a series of footbridges, then bear slightly to the left towards a long meadow with a stream to the left (and river beyond that). Proceed slowly and quietly to observe heron and egret by the edge of the stream.

Watch out for Heron and Egret along this stream
 At the top of the meadow follow the edge of the wood until you come to a track emerging from the wood on your left. Directly opposite the track look for a stile which takes the footpath uphill along the edge of a field. On the summit look back at the glorious view across hills and open fields - not a road or track in sight. The continue along the path for wonderful views across the Bure Valley.

The path eventually drops down to farm buildings, a cottage by a pond and the main farmhouse. Continue past the farmhouse (along a long drive) and eventually turn onto the start of a country lane. Keep to the lane (all the time keeping an eye out for Heron by the river, in fields to the right), until you meet another track to the left, just before Fring Wood Farm.

If you plan to stop for lunch at the lovely Saracen's Head (see below) then turn left along the track, otherwise spare yourself a fairly tedious, uninspiring walk by continuing past the past the farm for a short distance to rejoin the route at the next turn right.

The Saracen's Head meets you at the end of the track
After lunch and a beer at the Saracen's Head walk a short distance along the road (slightly busier than the lanes used so far), until you meet a signposted footpath uphill through a field to the edge of Calthorpe Hill Plantation - a private wood that in late spring is crammed full of bluebells. Keep to the footpath until you meet the road. Then turn right and continue until you meet another signposted footpath on the left, (just before the road meets Fring Wood Farm).

At the end of the track bear left onto a field edge path and keep a look out for a stile into the meadow on the right. Cross this and walk through the meadow, (at the right time of year - June - the meadow is full of yellow flag iris), to reach a footbridge over the River Bure.

From the footbridge over the River Bure - watch out for the Barn Owl
After the bridge cross a long wet meadow (a sturdy, wide, boardwalk has been constructed) to low lying woodland at the far end, where there is another footbridge. Eventually the path emerges onto a country lane. Turn right and almost immediately left, just before some cottages. Keep to right around the field until the path reaches Blickling Park. 

Follow the path to the left (or carry straight on to the Park gates and the ancient turnstile, if you want to bypass the Park and return directly to the car park) to The Lake.
The northern edge of The Lake in Blickling Park
 
 Follow the path along the lake edge until you meet the Hall and its walled gardens.

Blickling Hall at the southern edge of The Lake

Looking into the formal gardens from the footpath that surrounds them

Eventually the footpath emerges at the front of the imposing hall. The path then continues on to

Blickling Hall
the Buck' Arms Inn where you can reward yourself with good food and drink before returning to the car park located behind the Inn.



The Buck' Arms Inn

Depth of Field and Bokeh - more Wolfram Widgets

This post is all about determining camera setting to achieve a more precise Depth of Field - in particular for those difficult Bokeh shots - where the traditional calculations just don't seem to work. 

Lets start with another of my Wolfram Widgets - a traditional Depth of Field Calculator - and for those who don't know the diameter of the circle of confusion for their camera all you have to do is enter your sensor type and it's worked out for you.



And for completeness here is a Hyperfocal Distance Calculator.


These seem to work well for most landscape compositions. However when trying to achieve the maximum DoF (using the largest possible f-number)  the edges are often a bit soft. This is often due to camera shake or Diffraction. So for those using a tripod I've created a very simple Diffraction Limit calculator - it calculates the diameter of a spot  created by diffraction when a point of light is projected onto the sensor.



If the resulting diameter is greater than your camera's circle of confusion (this can be found in the results produced by the DoF calculator, for your sensor type) then any resulting image will be compromised by diffraction. That is a point of light will no longer be resolved to a sharp edged circle (of confusion) with diameter of approx 0.02mm on the camera's sensor. It will instead be resolved to a larger, fuzzy circle equal to the diameter calculated for the given f-number. Usually diffraction starts to become a problem at f-numbers greater than f/16.

But, if I follow all the time honoured advice on DoF, I am not always completely satisfied. If you have the same problem and in particular if you have problems applying DoF advice when creating Bokeh images read on. The problem is not your (or my) ability to follow the 'rules'; the problem lies in how we use the 'circle of confusion'.
Diagram showing the DoF Limits and the 'acceptable' circle of confusion at the sensor 

Consider the following:

The Depth of Field Calculator suggested that focusing on the card and using f/16 I would have a very narrow DoF (less than 3cm) 


I therefore assumed that the text on both the lens cap and on the mug in the background would be unrecognisable. So what's going on?
When a lens is focused at a certain distance, light from that part of the scene forms a point on the camera sensor. But, light from other parts of the scene, that are closer or further from the point of focus, form circles rather than points. These circles are referred to as circles of confusion. 
The closer to the point of focus the smaller these circles are and the further away they are from the point of focus the larger they are.

Now when we talk about DoF we are saying that points of light from that region will be rendered on the sensor as circles no larger than a circle which when printed on a 10x8inch print and viewed from 3ft by someone with 20/20 vision, will appear sharp.
  • On a full frame DSLR this is deemed to be a circle of diameter 0.029mm
  • On an APS-C Nikon/Pentax/Sony this is deemed to be a circle of diameter 0.02mm
  • etc.
However points of light from objects outside the DoF form larger circles but,..... they may still be recognisable, still 'in focus', albeit a little soft around the edges. For example consider the letter 'N' on the lens cap lying well outside the DoF, it's 6mm high. The letter will be rendered as a collection of white circles larger than the 'standard circle of confusion'(0.02mm on my camera), but much smaller than 6mm (actually 2.8mm - trust me for now, you'll see how this figure is calculated later). Now although each circle will overlap its quite obvious that the overall image of the letter will be recognisable. It will only become unrecognisable when points from the letter are rendered as much larger circles, (closer to 6mm).

There is an alternative way of looking at DoF (see Merklinger).

We can ask the question: If we projected a point on the sensor back through the lens onto a screen placed at point X, (less than D the distance to the point of focus) how big would the circle be?

The answer (according to Merklinger) is
Sx = (D - X).f/D.N

where f=focal length of lens and N = f-number


Similarly for a screen placed at point Y, (greater than D) the projected circle would have diameter:
Sy = (Y - D).f/D.N

Diagram showing the 'projected' circles at X, D and Y
(any object at Y smaller than the projected circle will be out of focus, larger and it will be recognisable but with soft edges)
Using these simple equations and substituting answers from my DoF Calculator, we can establish that the smallest object to be rendered sharp at the near limit of DoF is 0.122mm in diameter and at the far limit of DoF is 0.126mm. So any detail with a diameter of 6 - 8mm close to the DoF limits is clearly going to be recognisable, (even with the effects of diffraction, that cut in at f/16).
I clearly need another widget that calculates the f-number required to ensure near and far objects, of a given size, are out of focus.



And here are the results for my Bokeh image:


The calculator suggests that any f-number less than f/5.7 will produce acceptable results

The resulting image using f/5.6

Merklinger's equations are so simple to use and remember, and they offer such precise control over focus that I guarantee I'll be using them in future - who knows I might now even be tempted to venture into portraiture and macro photography.

Sun Locator

For some time now I've been looking for a simple application that would enable me to plan my location, at any given time, according to the position of the sun, (esp. at sunrise and sunset).

Finally I turned to Stephen Wolfram's inspirational new "Wolfram Alpha Widgets" site in order to build my own. The site is based on Stephen's new WolframAlpha search engine. Although still in its Beta version it's sufficient to enable the rapid build of some pretty impressive applications.

Simply enter the date and time and either the location's name or it's latitude and longitude; press submit and voila the application displays the sunrise, sunset, altitude, azimuth and location relative to the horizon throughout the day.

Enjoy.

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