Friday, June 21, 2013

Tavy railway bridge panorama

I'm not a practiced shooter of panoramic pictures but some subjects cry out for the ultra wide treatment.  A couple of weeks ago I went to Warleigh Point on the banks of the Tamar near Plymouth.  The aim was to shoot insects in the nature reserve (I did) but I couldn't resist shooting the railway bridge which crosses the Tavy where the Tavy and Tamar join.

Railway bridge over the River Tavy, Devon.  Click to enlarge.
One of the benefits of digital photography is the ability to stitch multiple shots together in software rather than requiring a dedicated panoramic camera such as the Hasselblad XPan back in the days of film.  In this case the bridge, set against a background of the rolling hills of the Tamar valley, needed a stitched panorama to avoid either cropping top and bottom or the inclusion of large amounts of sky or estuary mud if I'd tried to fit the whole width in a single frame.

Out came the tripod, on went the 180mm macro to get the right framing, the camera was set to manual exposure at 1/400 and f9 to avoid variations in brightness across the panorama, and I took 12 shots, tracking from left to right with decent overlap between the shots to make the stitching easier.

Back at my desk I processed the RAW files with identical recipes, batch converted to JPEGs and stitched the 12 files using Canon Photostitch (free with Canon DSLRs).  Sounds easy.  It's not.  You can't rely on the autostitching so each merge seam has to be merged using multiple points to get the best placement.  12 shots is eleven merge seams.  Get one out and it throws off your other merges.  And to check it's necessary to save the merge, check the resulting JPEG - and start again if a merge hasn't worked correctly.  I spent a little over an hour getting it right to produce a seamless panorama.  It may be easier in more advanced programs but I work with what I've got.

Even that wasn't the end of the process.  The resulting panorama needed straightening tp produce the correct alignment.  I use GIMP as my photo editor and this has a tool to set the correct angle.  In the case the alignment was easy.  I simply aligned the middle four spans at the point they met the river.  Just like using a spirit level.  A final crop and save produced a 25875 x 2947 px image, reduced by Blogger to 1600 x 182 for inclusion on this post.

I think it works well - and the original preserves all the detail inherent in a high resolution shot.  Detail like this of one of the supports.  Click for the 100% crop.

100% crop from Tavy railway bridge panorama
Now to find someone who can print it.  At ~300dpi it should work out to 90 x 10in / 225 x 25cm, even larger if I take the dpi down to 250 or even 200.  On second thoughts I'm not sure I've got that much wall space - especially if I repeat the process with the tide in.


I've added a 4000px wide image to Flickr.  Click here to view.  Right click on the Flickr image and choose original from the size options to see the larger image.

Friday, June 14, 2013

I have a little list....

...of butterflies I've never managed to get good photos of despite them being local.  For example, there's a few fritillaries that I've seen but never captured up on Dartmoor; green hairstreak - I can't seem to find the local populations; wall brown - I haven't seen a good specimen with camera in hand since my film days; and the small copper, which keeps eluding me despite being locally common.  Part of it lies in not being in the right place at the right time but sometimes it comes down to pure luck.  Sometimes it's bad luck.

The Holly Blue butterfly, Celastrina argiolus, is common enough locally.  I see it most years, fluttering around the hedgerows in search of its holly and ivy host plants.  Small, pretty - and always, it seems, tantalisingly out of reach.

Until the 5th of June this year.

I walked outside, camera in hand, and disturbed a Holly Blue feeding on my perennial wallflower.  It flew off before I could get a shot.  Another disappointment.  And then, 30 minutes later, it came back to feed on the wallflower.

Now was my chance.  I had the Tamron 90mm macro and 25mm extension tube on the 600D camera, flash on, AV set and everything ready.  I maneuvered into place.  The butterfly was feeding on the far side of one of the wallflower heads.  I quickly took a couple of shots as insurance, even though its head was out of sight.

Holly Blue butterfly, head hidden behind a flower of Erysium 'Wlaburton's Fragrant Star'
I'm glad I did.  Rather than - as I expected - move to a position where the whole butterfly would be in view it simply flew off.  And never came back.  Still, I suppose it's better than no photograph at all. 

I've been more fortunate with another couple of butterflies that were also on the list.  One recent day out, albeit in two different locations, yielded decent shots of a male Orange Tip and a Small Heath.

Orange tip butterfly, Anthocharis cardamines, male
Orange tip butterfly, Anthocharis cardamines, male
Small heath, Coenonympha pamphilus
 But I still want that Holly Blue.

As always, click the pictures to embiggen.

Monday, June 10, 2013

Dallying with the damsels

Damselflies that is, smaller and more delicately built than their larger dragonfly cousins, but equally photogenic.  Over the last couple of weeks I've been able to capture a few nice shots of three of the commoner local species, a promising start to the summer.

It started with a female Large Red damselfly, Pyrrhosoma nymphula, in the typica colour form, that wandered into the front garden at the end of May, giving me a chance for a few shots - including a close up.

Pyrrhosoma nymphula forma typica -  female large red damselfly
Pyrrhosoma nymphula forma typica -  female large red damselfly
A few days later a male showed up round the little pond in the rear garden and posed for long enough to allow me to get the 180mm macro lens onto a tripod to do some natural light / fill flash photography.

Pyrrhosoma nymphula  -  male large red damselfly
The hard part, as always with side views of insects, is getting the whole damselfly parallel with the sensor plane so that both the head and tip of the tail are in sharp focus.  Practice helps - but blind luck and a good few tries seem to be as important.  The extra working distance of the 180mm macro lens really helps.
Pyrrhosoma nymphula  -  male large red damselfly
A little further afield - well, close to the woods where I walk the dogs - I came across both male and female common blue damselflies, Enallagama cyathigerum.  Well away from the still water they prefer, they were both a bit skittish but, eventually, I managed to get some reasonable shots.
Enallagama cyathigerum - common blue damselfly male
Enallagama cyathigerum - common blue damselfly male

Enallagama cyathigerum - common blue damselfly female
Meanwhile, on the streams that flow down from Dartmoor, Beautiful Demoiselle damselflies are emerging.  Calopteryx virgo is one of two UK species with pigmented wings, brown in the case of females and immature males, iridescent blue in mature males.

Calopteryx virgo - immature male

Calopteryx virgo - immature male beginning to develop the blue wings of maturity
At the location I took the two shots above I didn't manage to capture an adult male - so here's one I photographed a couple of years ago.  They'll be more common in a few days, ready for my next trip out.
Calopteryx virgo - mature male
Of course, typically for immature males of any species, some can be very vain.  This one was quite happy to allow me to set up the 180mm macro and tripod at 1:1 working distance (about 18cm), maneuver around, and fire off multiple shots at close range to get some different views than the conventional side on or top down shot.  It even obligingly switched backgrounds while staying close to me.  In the second of the shots it's eating its lunch, a small midge.

Calopteryx virgo - frontal view of immature male

Calopteryx virgo - frontal view of immature male
An enjoyable start to what I hope will be a productive summer.

As always, click the pictures to access the larger versions.