Sunday, 13 January 2019

Into the Orion Nebula

Orion Nebula (reprocessed)
M42, Orion: Tele Vue 60 + Canon 80D + Vixen Super Polaris
"An unformed fiery mist, the chaotic material of future Suns" - William Herschel, 1789 
Herschel's description (written long before spectroscopy revealed the true nature of gaseous nebulae) could hardly have been more prescient. The Great Orion Nebula (Messier 42) is indeed a cradle of new stars (at 1,300 light years, the nearest star-forming region to our own sun), visible to the naked eye as a misty patch in Orion's Sword on winter nights.

Viewing M42
I'm occasionally asked what it looks like through a telescope: a one-word answer would be "Majestic", but don't expect to see the full extent of the nebula - or indeed the vivid colours that you get in photos like the one above. As with most deep-sky objects, the Orion Nebula rewards careful and prolonged examination. Here's a sketch I made a long time ago (for GCSE Astronomy coursework!) illustrating the typical low-power view through a small telescope under suburban skies:

One telescopic feature you won't often see clearly in photographs is the Trapezium, a tight grouping of four hot young stars whose ionising radiation has helped sculpt the nebula into the shape we see today. In my 4-inch refractor the nebula is nicely framed in a 24mm Panoptic eyepiece (42x magnification) with layers of nebulosity building up to the core. Add in an Ultrablock filter to improve the contrast and the nebula takes on the appearance of a swooping bird of prey. With a 5mm Nagler (200x) under steady skies, a fifth member of the Trapezium is just visible.

So far the weather has only allowed me one opportunity to look at M42 with the XT10, but even under less than ideal viewing conditions it was immediately obvious that the extra aperture had improved the view dramatically. The core region had a strong green tint and averted vision made it so bright that the Trapezium was almost lost in the glare. Lots of finely detailed structure was visible with dark rifts cutting through the nebulosity. The Ultrablock filter wasn't really necessary for such a bright object, but it did seem to increase the overall extent of the nebula, particularly on the northern side.

Photographing M42
For any birders who've made it this far, the Orion Nebula is arguably to astrophotography what the kingfisher is to bird photography, the gateway drug that lures you into a lifetime hobby. (It even comes with its own fish, of a sort.) The image at the top of this post is a stack (not a mosaic) of 108 thirty-second exposures (plus 15 dark frames and 21 flat frames). As I'm still shooting unguided (for now) I've been careful not to choose targets too far away from the celestial pole, so at -5 degrees declination M42 presented the biggest test yet of my polar alignment accuracy. Fortunately the Great Nebula is a forgiving target - you can pull out a considerable amount of detail and colour even with relatively short 30-second subs. If you look closely, some slight trailing is evident, but not enough to spoil the final image.

Processing M42
As I've said before, acquiring all the light-frames (plus darks and flats) is only half the battle; there's still a lot of work to do. The image above was assembled using the freeware program Sequator. Compare it with my first attempt using the more widely-known freeware DeepSkyStacker. The samples on the Sequator website suggest it's optimised for landscape astrophotography (i.e. wide-angle shots in which the horizon is visible), but it seems to do an equally good job for deep sky photography. In terms of workflow, I certainly found it easier to process the stacked image produced by Sequator. As you can see in the mouse-over comparison below, Sequator did a much better job of retaining the detail around the Trapezium area. There's less noise too, although the DeepSkyStacker version shows more of the fainter regions of the nebula.


It's also worth noting that Sequator did an excellent job of identifying and removing the light pollution gradient. DeepSkyStacker doesn't cater for this so I used the Light Pollution Removal tool in Noel Carboni's Astronomy Tools Actions set (which, despite having more user control, did on this occasion leave a series of contour lines in and around the brightest parts of the nebula). The Sequator stack did contain some colour noise, but this was easily removed using the Colour Blotch Reduction tool from the same set.

Other pros and cons: Sequator was fast (less than 30 minutes processing time compared to up to an hour for DSS). However, it also left some curious purple "appendages" around some of the brighter stars, as shown in the crop below:

I've seen Sequator described as "stacking for dummies" on one popular astro-forum, but on the above evidence I think it'll be this dummy's image-stacker of choice for the foreseeable future. This is by no means an outright rejection of DeepSkyStacker, but more likely an indication that I still haven't figured out how to get the best out of it.

I like the colours better in the Sequator version too, although that's a matter of personal taste.

Which one do you prefer?

Sunday, 30 December 2018

2018 in Pictures

I didn't think I'd be able to top the previous year, but 2018 served up a bumper crop of sightings (September in particular had enough highlights to fill a best-of list all by itself). But here for your viewing pleasure, after much vacillating, are the pick of the bunch:

There's nothing like a Waxwing to brighten up a dull winter's day:

Waxwing (Bombycilla garrulus)

I've got to include at least one Kestrel (it's the Law) and this bird was a bit special:

Kestrel (Falco tinnunculus)

Why go to the trouble of catching your own frog when you can steal one from a Marsh Harrier?

Buzzard vs Marsh Harrier

The light wasn't great that morning, but it's not every day that a Cuckoo pops up right in front of you:

Cuckoo (Cuculus canorus)

Here's something else you don't see every day, a Mole out in the open:

Mole (Talpa europaea)

...though it really wasn't the best day for small furry things to come out of hiding.

Also at Stodmarsh, a Hobby grabs an in-flight snack:

Hobby (Falco subbuteo)

At Foreness Housemartins collect mud for their nests:

House Martins (Delichon urbicum) 

And a Stoat pops up at Stodmarsh:

Stoat (Mustela erminea)

A typically quiet month for birds, but not for dragonflies such as this Norfolk Hawker:

Norfolk Hawker (Aeshna isoceles) 

Last ones to arrive; first ones to leave. A Swift prepares for its autumn migration at North Foreland:

Swift (Apus apus)

1st September at Grove Ferry was one of those rare and remarkable days where everything falls into place. It included Spotted Flycatchers and a Bullfinch (in the same tree), a Whinchat, and even a surprise Bittern. But it was the reserve's star attraction that stole the show:

Kingfisher (Alcedo atthis)

Return visits later in the month uncovered a Small Copper butterfly (the first one I can recall seeing at the reserve), plenty of Willow Emerald damselflies, Lizards, and this juvenile Green Woodpecker:

Green Woodpecker (Juvenile) 

Winter birds start arriving along the coast, including this handsome Brambling at North Foreland:

Brambling (Fringilla montifringilla) 

Not the best photo, but arguably the best bird of the year; Scott Haughie's White-billed Diver (in summer plumage!) which attracted birders and photographers from across the country:

White-billed Diver (Gavia adamsii) 

I expect I'll be frowned on in some quarters for including it, but this ESCAPED Hoopoe brought some entertainment (unless you're a grub) to an unlikely part of Thanet:

Grub's Up (again)

Another month, another loon; a Red-throated Diver (not in summer plumage) in Ramsgate Harbour:

Red-throated Diver (Gavia stellata)

All the photos on this page were taken with a Canon 80D DSLR and the trusty Tele Vue-60 refractor.

In the next post, I will be returning to outer space.

Wednesday, 22 August 2018

A Journey into Astrophotography

I'll say one good thing for He-Who-Must-Not-Be-Retweeted; he's encouraged me to turn my attention away from this increasingly nonsensical planet and back into deep space*. I've dabbled with astrophotography before (hand-tracking with a 50 mm lens), but mostly I've stuck to the brighter objects like the moon and Jupiter. Long-exposure astrophotography at focal lengths greater than 300 mm requires precise motorised tracking, but it was only after a trip to Astrofest 2018 (and some intensive research) that I figured out a practical and affordable way to go about it.

Here's a picture of the trusty Tele Vue-60 (the same scope I use for most of my wildlife shots) in its latest mode atop the equally trusty Vixen Super Polaris mount (fitted with Skywatcher dual-axis motor drives and an ADM dovetail plate adaptor):

With a field-flattener attached the TV-60 is roughly equivalent to a lens of 400 mm focal length. So far, this arrangement is good enough for exposures up to about two minutes duration depending on the accuracy of my polar alignment. (The Skywatcher handset does have an ST-4 port for autoguiding should I wish to attempt longer exposures in the future.) Here's another angle showing the motor drives attached to the Right Ascension and Declination axes:

Any serious astrophotographers visiting this blog might be shaking their heads at this point and muttering about vignetting and edge-of-field distortion, red sensitivity, thermal noise etc. in much the same way that serious wildlife photographers might mutter about autofocus and aperture control when they see what I'm using. But the point is, I don't get enough clear, moonless nights a year to justify spending the kind of megabucks that others spend on their gear. And, crucially, I can use the same DSLR and the same little scope for multiple purposes (which probably explains why the focuser is starting to look a little worse for wear). And (whisper it quietly) one good photo of the Orion Nebula looks very much like another good photo of the Orion Nebula, no matter where you are on the earth. Unless you have your own observatory equipped with an adaptive optics system, you're probably not breaking new ground.

That's not to say I won't be eagerly imaging the Orion Nebula when I get the chance just like every other amateur, but M42 is a spectacle of the winter sky, so for my first target I chose the globular cluster M13 (because it's big, bright, and not too far away from the north celestial pole):

M13 Globular Cluster
M13, Tele Vue-60 + Canon 80D (30 x 1 min @ ISO 800)

The long exposure times required to make an image like this turn pinprick stars into blobs of light, giving the false impression that they are almost touching each other. Although direct interactions in globular clusters do occasionally happen (the most likely origin of blue stragglers), the average distance between stars in a typical globular is actually 0.1 to 0.5 light-years, a fraction of the distance between here and Proxima Centauri (4.2 light-years), but still many times the size of our planetary system. This image from the Hubble Space Telescope resolves the core of M13, giving a better impression of the star density. Around 150 globular clusters are known to orbit our galaxy, dipping in and out of the galactic plane in highly inclined orbits. To put that in perspective, M87, the giant galaxy at the heart of the Virgo Cluster, is surrounded by 16,000 globular clusters.

I recently had the pleasure of looking at M13 through a 10-inch telescope and the result was breath-taking (so much so that I completely forgot to look for NGC 6207 - the "little" galaxy visible towards the bottom-left of the image above).

In my 4-inch achromat M13 takes on the appearance of a "grainy snowball thrown against a pane of glass", always on the brink of being resolved but never quite making it, except when averted vision is employed. In the 10-inch scope (at 133x magnification with a 9mm Nagler eyepiece) it was transformed into a vast three-dimensional city of stars, its brighter members glinting like crushed diamonds right across the face of the cluster, with hundreds - perhaps thousands - more revealing themselves in averted vision. The longer I looked, the more impressive it became, as I began to discern chains of stars arcing out from the centre.

M13 is arguably the most spectacular globular cluster visible from UK latitudes, but there are several others which run it close, such as M3 in the constellation Canes Venatici:

Messier 3
M3, Tele Vue-60 + Canon 80D (31 x 1 min @ ISO 800)

Of course, acquiring the images is only half the battle; processing them is an art-form in itself. I'll leave those details for another time as I'm still very much a beginner at this, but if you want to know what software I used, the links are here.

In the meantime, if you ever get the opportunity to look at M13 or any of the other showpiece globulars through a medium to large-sized telescope, I strongly recommend it. Drink in the spectacle, contemplate what you're seeing, and then look at it again. Photographs just can't do it justice.

See more of my TV-60 deep-sky photos on Flickr.

*Famous last words... While I was drafting this post, He-Who-Must-Not-Be-Retweeted announced the creation of SPACE FORCE (I swear I can hear the echo as I'm typing it). It seems there really is no escape from the Tangerine Nightmare.

Sunday, 13 May 2018

Birds of East Kent: Kestrel

Latest in an occasional series of posts discussing the different birds that can be found in East Kent and how easy (or not) it is to get a decent picture of them.

Kestrel (Falco tinnunculus)

I don't usually bother with top-ten lists or stuff like that, but if I had to choose a favourite bird it would undoubtedly be the Kestrel. It's not the biggest (or smallest) bird of prey; nor is it the most colourful. It's not even the only British bird that hovers, though the other contenders can't hope to match its precision or its tenacity. But, more than any other bird, it's always been a small part of my life in some shape or form. It was there on the striking red badge I received when I joined the YOC:

It was there in Ken Loach's famous film (adapted from the novel by Barry Hines) that I saw in my early teens. And it was there at the start and end of the summer holidays, glimpsed from the side window of a car; a bird that seemed to defy not just gravity but time itself as it hovered above the roadside verges while the twentieth century flowed around it.

Kestrel (Falco tinnunculus)

I've had the privilege of seeing a wild kestrel up close on a couple of occasions, most recently in February of this year when I encountered one perched in a small tree by the North Foreland golf course. I took some photos and continued on to Botany Bay to see if there was anything interesting on the shore. When I turned around to walk back I was surprised to see the same kestrel standing on a fence post. Naturally, I couldn't pass up the opportunity to take some more photos:

Kestrel (Falco tinnunculus)

From badges to films to poetry (see: The Windhover by Gerard Manley Hopkins) there is something about the kestrel that seems ingrained in the British psyche. A good example of this can be found in Powell and Pressburger's 1944 wartime classic A Canterbury Tale. In the film's prologue, a group of medieval pilgrims make their way towards Canterbury while a voiceover narrates a passage from Chaucer's text. A falconer stops to release a kestrel into the sky. The bird dips and soars ... and transforms into a Spitfire flying above the English countryside. Four hundred years of history spanned in a single cut.

If the description of that scene rings a bell it's because Stanley Kubrick used the same trick in the famous bone-to-spacecraft transition in 2001: A Space Odyssey. Coincidence, homage or blatant rip-off? It's a question that's been debated for fifty years, and will probably be debated for fifty more. In the meantime, the kestrel continues to soar above fields, along cliff-tops, and across marshes - hovering, observing, sometimes descending for prey, and then moving on, seeing colours that no human eye can see as it patiently constructs its daily map of the world.

Effortlessly at height hangs his still eye.
His wings hold all creation in a weightless quiet,
Steady as a hallucination in the streaming air. 
Ted Hughes, The Hawk in the Rain (1957)

See also:
More of my Kestrel photos on Flickr
Kestrel (RSPB)
Kestrel (Birdforum)
Kestrel (Birdguides)

Sunday, 24 December 2017

2017 in Pictures

I normally leave end-of-year round-ups to the more prolific bloggers, but this year I've taken a lot more photos that usual, partly because I bought a new camera, and also to serve as a welcome distraction from the daily hourly news maelstrom generated by Brexit and He-Who-Must-Not-Be-Retweeted. It's reassuring to know that there are still some quiet corners of the world where wagtails still wag, kingfishers still fish, and kestrels still hover, unconcerned by the sound and fury of angry old men who never stop to listen.

But enough of all that; here are some highlights.

Photographers often rhapsodise about the "golden hour" just before sunset, and it doesn't get much more golden than this:

White on Gold

A Water Rail breaks from cover at Grove Ferry:

Water Rail (Rallus aquaticus)

This colourful Pheasant took it upon himself to greet visitors to the Stodmarsh car park:

Pheasant (Phasianus colchicus) 

A smart Shelduck flies overhead at North Foreland:

Shelduck (Tadorna tadorna)

A dull and drizzly May Day at Grove Ferry was livened up by this magnificent Kingfisher (one dive, one fish caught, one lucky photographer):


Later in the month, a decent view (for a change) of a Cuckoo:

Cuckoo (Cuculus canorus)

The dragonflies at Grove Ferry / Stodmarsh attracted lots of visitors, including this dashing Red-footed Falcon:

Red-footed Falcon (Falco vespertinus)

Fortunately there were still plenty of dragonflies left after the Red-footed Falcon departed, including this Norfolk Hawker (aka the Green-eyed Hawker):

Norfolk Hawker (Aeshna isoceles)

Lots to see in North Yorkshire, including Red Grouse:

Red Grouse (Lagopus lagopus)

...and the famous Gannets of Bempton Cliffs:

The Gannets of Bempton Cliffs

Back in Kent, a relative newcomer to Grove Ferry, a Willow Emerald Damselfly:

Willow Emerald Damselfly

Some drastic Photoshopping saved this image from the bin. The Marsh Harrier changed direction so suddenly I cut off half of the upper wing and had to clone it from the other one. I wouldn't normally do this much work to an image, but I think in this case it was worth it:

Marsh Harrier

Fortunately my reflexes were a little better when this Kestrel made a quick getaway:

Flight of the Kestrel

After seeing a Red-throated Diver in 2014 and a Great Northern Diver in 2015, I wondered how many years I'd have to wait to see a Black-throated Diver in Ramsgate Harbour. Turns out it was only two:

Black-throated Diver (Gavia arctica)

Another new visitor to Ramsgate Harbour, an Iceland Gull:

Iceland Gull (Larus glaucoides)

The year started with a Little Egret against a golden backdrop, so it seems fitting to end it with its larger cousin, a Great White Egret, looking for fish in front of the golden reeds of Grove Ferry:

Great White on Gold

No autofocus was used in the making of these pictures.

Saturday, 28 October 2017

Shooting with the Canon 80D

Kingfisher (Alcedo atthis)
Canon 80D & Tele Vue 60 refractor, 1/1250 sec, ISO 640

I tend to steer clear of technical write-ups on this blog as the Internet is already stuffed with photographers telling you all about what their camera can do rather than what they've actually done with it. However, given that the bulk of the traffic to my Flickr pages this year has been driven by people specifically looking for photos taken with the Canon 80D, I thought I'd share my impressions after several months of shooting with it. Please bear in mind that this is all very subjective and I can only compare the 80D against other Canon DSLRs I've used (namely the 350D, 40D and the 7D Mark I).

Noise-handling is significantly improved over the 7D Mk I. Tastes vary of course (I don't mind a little grain as long it doesn't look too obviously "digital" - and I actually prefer it to the over-aggressive noise reduction that some photographers insist on), but I find the 80D gives exceptionally clean images up to ISO 400, and stays workably clean all the way up to ISO 3200. The image below was taken in very gloomy conditions at ISO 3200, but I was still able to get a good 12x8 print out of it.

Coot Chicks
Canon 80D & Tele Vue 60 refractor, 1/1250 sec, ISO 3200

From ISO 4000 the noise gets progressively more obtrusive, but still manageable (as demonstrated in this shot of a black cat, taken in poor light at ISO 5000 and downscaled to 12x8). Even at the highest ISOs the 80D's large pixel count means that you should be able to get an acceptable 6x4 print provided you don't have to crop too much.

The 80D's default colour setting seems slightly desaturated compared to previous models, but this can be easily fine-tuned in-camera or in post. The "Peacock Butterfly" test certainly produces reds that look closer to nature than the over-saturated reds of older Canon DSLRs.

I use manual focus for most of my wildlife photography so I can't really contribute anything to the 80D vs. 7D Mk II autofocus debate, but on the occasions I've used the touchscreen focus I've found it to be fast, responsive and very intuitive to use. If, like me, you plan to use your camera for astrophotography now and then, you might consider the 80D's articulated touchscreen to be a more valuable feature than the 7D Mark II's advanced tracking.

Birds-in-flight are always going to be a challenge using manual focus, but so far I've found that my hit-rate is better than with any previous Canon DSLR. Would autofocus have successfully tracked this tern or would it have zeroed in on the coots in the background?

Tern (with fish)
Canon 80D & Tele Vue 60 refractor, 1/1600 sec, ISO 400

Much has been made of the 80D's improved dynamic range at lower ISOs, and you'll find plenty of examples online where photos have been deliberately underexposed by an extreme number of stops and then fixed in Lightroom/Photoshop to demonstrate the camera's capacity for shadow recovery. In real-world terms you'd have to be doing something drastically wrong to underexpose a photo by that much without realising (and the metering is almost always spot-on - more so than any other camera I've used), but the improved DR does give you scope to be more adventurous in your post-processing, especially when trying to emphasise a particular mood. See this black-and-white shot of Whitby Abbey below for an example (move your cursor across the image to toggle the before-and-after):

Canon 80D + EF50mm f/1.8; 1/250 sec, f/8.0, ISO 125

I'm struggling to think of anything I don't like about the 80D: I miss the mini-thumbstick from the 40D and the 7D, but the touchscreen makes up for this. Overall the Canon 80D is a user-friendly and feature-packed camera (including settings for time-lapse, multi-exposure, minimum shutter speed, flicker detection, and so on) that does everything I would want from a DSLR.

See also:
More of my photos taken with the Canon 80D

Monday, 8 May 2017

Answer: "It's a Tele Vue."

Pheasant (Phasianus colchicus)

The question being, typically: "What's that on the end of your camera?"

As the name of this blog suggests, I do most of my photography with a telescope - a Tele Vue-60 refractor to be precise. What it lacks in autofocus and aperture control it more than makes up for in sharpness and colour correction. It's compact and portable and it doesn't need to be stopped down to hit the sharpness sweet spot. Recently Tele Vue embraced the world of social media and - as part of their ongoing 40th anniversary celebration - they asked if they could feature me on their new blog, in particular why I chose the TV60 and why I've stuck with it over the years. You can read the resulting post here:

Three scopes in one: astro-scope, spotting scope and telephoto lens

Astronomers of course need no introduction to Tele Vue, but for those who don't know, they're a Chester, New York-based company founded in 1977 by Al Nagler. Prior to that Al designed lunar landing simulators for the Apollo missions, using his knowledge of optics to create realistic wide-field vistas to aid the astronauts' training.

Tele Vue started out making lenses for large projection-screen televisions, but they've since become renowned for their high-quality eyepieces and telescopes. If you ever get the chance to look through one of Tele Vue's wide-field eyepieces, I highly recommend it. They call it the "spacewalk" experience and with good reason: if, like me, you started out in astronomy squinting through a cheap and cheerful 0.965" eyepiece, the difference is startling. When looking through a Nagler it's as if the eyepiece "gets out of the way", leaving you immersed in the stars (or suspended above the moon if lunar observing is your thing). And if the 82-degree apparent field-of-view of a Nagler isn't enough for you, they also do an Ethos range, which goes up to a whopping 100 degrees.

In the interests of fairness and transparency I should point out that:

a) Other telescopes and eyepieces are available
b) I was not offered any incentive by Tele Vue (financial or otherwise) to contribute to their blog or write this post. I'm just a proud TV-60 owner and I wouldn't dream of parting with it.

See also:
Tele Vue home page
My TV-60 photos on Flickr