Cornish Skies vs Hertfordshire Skies

[Knight of Clear Skies]

Here's two sets of widefields taken from Crowdy Reservoir on Bodmin Moor, Cornwall, and a site just up the road from me in south-east Hertfordshire, about a mile north-east of the town of Ware. The same camera, lens, exposure settings and processing were used for both sets - Samyang 14mm lens at f2.8, Canon 700d (unmodded), 30 seconds at ISO 800 (with a +0.67 brightness adjustment in Canon DPP, as the Cornwall shots came out a little dark when I reviewed them. I think this makes them equivalent to ISO 1,300 or so). If your monitor is wide enough I've put the views side-by-side.

View to the East. The planes in the Hertfordshire shot are from Stansted Airport, lots of jets and contrails around here.

View South. (The Hertfordshire shot is particularly bad here as that's London in the distance, the bright lines are contrails.)

West.

North.

Zenith (straight up would be somewhere towards the top of the frame in both pictures, as the tripod handle catches).

The Crowdy reservoir pictures were taken at the end of November as part of a set I took to support Cornwall Council's Dark Sky bid for Bodmin Moor. I took the Hertfordshire pics last night. I haven't got things quite right, there is more horizon and less sky in the Hertfordshire set, but they should be pretty good for comparison purposes. I think you can see why I do most of my imaging from Cornwall.  Would be interesting to see similar shots from around the UK to see how they compare. While not everyone has the Samyang lens I'd have thought a 30 second shot with a kit lens at f3.5 and ISO 1600 would give something in the same ballpark as the above.

Despite appearances, the skies up here in Hertfordshire aren't terrible, on a decent night I can make out the Milky Way and Andromeda. While views to the south are very restricted there is another site I've used which has better views to the west than the one above (surrounded by trees though). Driving a few miles north would also help me, although I've yet to find anywhere suitable. On the other hand, the roads were dry last night - lots of LED lighting is being installed around here and I don't know how bad the reflections are when it's wet.

This is my most successful image from Hertfordshire, 14 minutes on Comet Catalina & M101 with a 135mm lens at f3.4. While I had to use GradEx to clean up the background, M101 was bright enough to punch through the LP when well positioned.

Something I haven't tried up here yet is my Ha filter, would be interesting to see how much LP leaks through it. I'm also thinking about investing in a 3nm Ha filter for my new 1600MM-Cool camera to open up my skies more.

Hope you find these interesting.

[Alan White]

Very interesting indeed.
I was taken aback by how dark Cornwall skies were last summer, winter skies if cloud free must be wonderful.
Light pollution is such a blight for us astronomers!

[Gazabone]

Makes me feel very lucky to live in Cornwall (despite the weather!). Thanks for posting. 

[James]

I used to live in St Albans (now in Devon luckily) and I spend a week in Cornwall every April with my in-laws, on the Lizard, and yes, the skies are really dark. There's a quarry or two dotted around and there always seems to be someone with external lights on full - to keep the Cornish Piskies away... so I recognise the two sets of picture in LP terms...

I have the same lens but tend to put a 6D on it, or a modded 650, Ill try and see if I can get some pictures done locally (near Exeter) using the same settings you've used  My skies here are in between the two sets you've posted - luckily  bit more like the Cornwall ones!!

James

[laudropb]

Very nice, if sad, comparison.

[johnfosteruk]

We go to a spot near Mullion once a year now, for many reasons, one of which is the dark skies, it's tremendous.

Being in Plymouth I can hop over the bridge whenever I fancy but a week away under Cornish skies is just another level of tremendousness.

[Pete Presland]

its a sad state of affairs, I am just up the road in Bedfordshire and it gets worse every year!

[Knight of Clear Skies]

On 19/02/2017 at 14:17, James said:

I have the same lens but tend to put a 6D on it, or a modded 650, Ill try and see if I can get some pictures done locally (near Exeter) using the same settings you've used  My skies here are in between the two sets you've posted - luckily  bit more like the Cornwall ones!!

James

Would be interested to see them, I also wonder how much difference the camera would pick up from night to night.

On 19/02/2017 at 16:17, laudropb said:

Very nice, if sad, comparison.

It is a shame, as a good chunk of the LP is unnecessary and a waste of energy to boot. On the other hand the 30 second exposure with the fast lens makes it look worse than it really is, even over London I can make out M42 naked-eye. I can still enjoy the skies in Hertfordshire, despite their limitations. The new LED lighting strikes me as overly bright but at least councils are wising up to the benefits of turning banks off after midnight.

[FenlandPaul]

Really interesting comparison. Cornish skies are lovely.  Last Summer we stayed a couple of weeks at the lighthouse keeper's cottage that overlooks Sennen and Lands End.  Once the hideous Lands End visitor centre lights were switched off at around 11pm, it was Milky Way right down to the horizon.  Stunning.  Looking forward to popping back this Easter for a week.

The pic of M101 is spot on - shows what can be achieved from the less than ideal conditions most of us spend most of our time under!

 

Paul