photography – Richard Mudhar

Scorhill Stone Circle panorama

I wanted to try out panoramic photography at Scorhill stone circle near Gidleigh in Dartmoor as well as tinkering with radio. I didn’t have much time there, it’s a tough drive through winding roads and Google maps had already warned me that I had about an hour on site tops if I wanted to make a meeting in Exeter in the afternoon. It’s worth a rematch, because there’s quite a lot of interesting stuff within a mile, what with the Shovel Down stone rows and possibly another circle to the northwest.

A long time ago I had ambitions to take panoramic pictures of stone circles. The moving panorama thing really sings with megalithic stone circles, they don’t move so much so you don’t need video for the immersive experience, and we have 900 stone circles still extant in the UK, mainly in the west of the country. Those were the dotcom days of Apple QTVR and plugins, and hardware that was only just up to the job. QTVR is pretty much dead now. Backwards compatibility isn’t really in Apple’s DNA. The problem with QTVR was these had to be encoded in that format, because computers weren’t hard enough to do the processing of the source file on the fly like Panellum does. So these images are lost in Apple-history-land, although the source files I do have show just how poor digital cameras were¹ in the 2000s, the pictures won’t particularly benefit from being QTVR un-munged and re-munged to whatever is the panoramic tech of the moment. On the plus side, the stones are still there so a reshoot is possible 😉

Panoramic photography images are big – the panorama is 1Mb in size, so I’ve put it after the read more break. They aren’t as big as John’s trig point images, but the great advantage of a stone circle is that all the action is in the near field, you don’t have to zoom in so much.

dogs and dappled light

I shot these pics raw, because there was a weak sun through the haze, so I thought I could push some of the shots, However, the weak sun came through dappled cloud, and Sod’s law seemed to say that in one direction the cloud closed in again just as I passed the same direction the second time². I have a Kaidan Kiwi-L and it is sweet, compared to trying to spin round a stone circle on a monopod with the integral level. Some of the win is that the click stop forces you to take enough pictures, and you can mount the camera vertically. There are much cheaper ways of doing this now – well, after you have amortised the cost of the 3D printer.

Kaidan made a big fuss of how you should adjust your camera so it spins around the nodal point, and early software used to be critical on that. I do still try and match that, but either Autopano Pro is a lot less critical of getting that right or I have become a slovenly panorama maker because it seems less critical now. With a stone circle much of the action is at a reasonably constant distance from the lens and the foreground is often miscellaneous grass so maybe a bit of parallax error in the foreground isn’t seen so much as when doing a panorama in a building, with all its straight edges calling out a poorly centred camera.

Scorhill has a lot of human traffic – dogwalkers abound, and I waited about 10 minutes while a lady did her callisthenics in the stone circle. This shortened the photoshoot, I just about took the Kaidan twice round the circle in varying light before some more hikers with a huge hound hove into view and I figured I needed to clear site to head off to Exeter. I could push the exposure for the darker pics, but the problem is the light is different as the sun went in, so they don’t match well.

lighting for panoramas

I need to think differently about lighting for panoramas, since they’re inherently more tricky. You can’t keep the sun behind you with a panorama by definition, and the golden hour is also not ideal. What looks great on a still in one direction will be the sun low in the sky and great big long shadows in the other. Exposure is easy with an overcast sky, but that sky is so boring. It’s probably safe to say too much contrast is a problem in panoramas, because many of the photographer’s tools to minimise it can’t be used through 360 degrees

Probably the best light for stone circle panoramas is a blue sky with plenty of fluffy clouds, one of which is over the sun for the entire duration of the panoramic spin. Panoramas may be more suited to the mid-morning and mid-afternoon, a little bit off the ghastly high-contrast sun overhead at noon time and get some shadows to give modelling but before shadows get out of control.

Look ma, no Linux

Getting away with modest zoom ranges is just as well, because you seem to need Linux to run the splitting program generate.py to get multiresolution images. I don’t have a GUI on my linux box and have already had to rebuild it three times when some software digs itself into a hole I couldn’t get it out of. So when I spot requirements like so

To be able to create multiresolution panoramas, you need to have the nona program installed, which is available as part of Hugin, as well as Python with the Pillow package. Then, run

I think, right, move along now, nothing to be seen here…

When I tried Hugin years ago there was some hoohah about the patented SIFT algorithm, so you got to manually select the tracking points, involving lots of swearing when it didn’t work. Life is too short for that sort of thing.

So I bought Autopano Pro, and they were nice enough guys to trace my license key even though 11 years have passed and I have a new email address, so that is how I process my panoramic images. Kolor is now closed.

It appears that the SIFT patent will expire next year, which is good. Software patents suck. If they exist at all, they should be on a much shorter scale – software and Internet time is shorter than dog years so a maximum term of five years would let you get dominance without jamming progress in a field for over twenty years.

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Olympus E-PM1 camera left-hand thread screws to catch fixers out

This post is as a public service. WARNING – an Olympus E-PM1 camera has some LEFT-HAND thread screws. I’ll show you where these blighters are later.

Manufacturers really seem to hate people taking their gear apart, but I’ve never come across Olympus’s sort of craftiness before. There’s no good reason for them to make these screws left-hand thread, other than to make you strip the soft plastic they’re set into if you have the temerity to try to take your own property apart. Evil bastards. It’s not like a bicycle crank on the left-hand side, where there’s a damn good reason for the left-hand thread.

I quite liked this camera, despite the plastic battery door hinges breaking off after a year. It’s pocketable, but can take a decent EVF if necessary, I have a VF-4. I recently dropped the camera, and on power-up I hear this noise (recorded form about 2cm away). The clunk is fine and has always been like that, the death rattle is new.

Which does not fill me with confidence that this camera is long for this world, although the pictures are fine. I can almost count the plastic gear teeth wearing, and it’s loud enough to draw attention, which is a drag for photographing people. I suspect it’s slower off the mark than it used to be, too. So I thought I’d pop the back and take a look to see if something is obviously wrong. Continue reading “Olympus E-PM1 camera left-hand thread screws to catch fixers out”

Wolf Supermoon

The first day of the New Year features a full wolf supermoon, ¹ when the Moon is closest to the earth so brighter and bigger. The Moon was lovely so I figured I’d try for a shot. the Independent tells you why it’s a Wolf moon.

The Moon disc itself is as bright as the beach on a summer’s day when you are taking a picture of it, because it’s in full sunlight, no clouds and about the same distance from the sun as the Earth. Should be a doddle – I got the Canon EF 100-400 lens that I cleaned up, put it on a monopod and aimed at the Moon. f/8 1/400 ISO200 go.

Turns out not to be as easy as that. I needed a tripod, switched off IS and even then not every shot was equally sharp, must find the remote cable for the Canon, maybe it’s mirror slap. Took the best, that’s the top picture. I then tried my Micro Four Thirds camera with a 100-300 lens – the MFT sensor is probably smaller than the APS-C sensor on my EOD450D so the 300 end is probably comparable with the 400 on the Canon Continue reading “Wolf Supermoon”

Infrared camera trigger experiments

Wouldn’t it be nice if I could take a picture of a bird as it passed through an invisible beam of light? The idea’s not original, these things exist, but they are quite dear, so I am experimenting with making these.

The most obvious way is a light source and a photocell, and indeed many years ago at secondary school I developed an analogue circuit[ref]people normally consider monostables as digital but mine was built using discrete transistors and resistors, and the time delay was infinitely variable, as it would be with a CMOS 4538, so I consider it analogue[/ref] using OC71 transistors scavenged off postwar computer boards to make up monostable multivibrators for the delay elements and one with the black scraped away from the housing to act as a phototransistor.

Not bad for a school project from 1976. It looks better as an animation than a sequence of stills.

This gonzo technology of 40 years ago triggered the flash for the source negatives used in the animation – you set a very slow drip, and as the drop passes the photocell it triggers the delay. By increasing the delay between the drop passing and the flash going off you get the progressive animation, assuming each drop makes a similar pattern.

This was done with a manual camera, a new Canon AE1 ISTR that one of the other kids had. But the trick is to do all this in the dark, click the camera on Bulb and use the trigger to trip the electronic flash, which responds within milliseconds and has a short duration of about a millisecond if you reflect some of the flash back into the photocell of the flash (to turn it off as early as possible).

So there’s nothing incredibly hard about doing this, in controlled conditions, in a darkened room. If I were doing it again, I’d do it in the same basic way, using a phototransistor and a CD4538 CMOS dual monostable rather than a discrete monostable – one half to give the delay controllable with a pot and the other to make a pulse off the falling edge to go into a NPN transistor to trip the flash. There’s no need to muck about with PIC microcontrollers or Arduinos though you could do it that way if you really have to for a higher cost plus the aggravation of writing code, plus the jitter of the Arduino sampling the sensor/responding to the interrupt. In high-speed photography sub-milliseconds matter.

Everything gets harder outdoors

Outdoors you have massive and variable amounts of light from the sun, distances are longer, there’s just a whole lot more hurt all round.

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Using near IR to look for photosynthesis and plant health with NDVI

The NoIR Raspberry Pi camera comes with a blue filter to do near infrared photography – the blue filter ices the visible red but passes near IR which records as red, apparently.

NDVI image of something in the polytunnels. Should have made a not of what this plant is 😉 Anyway, more red and going to magenta white overload=more photosynthesis

NDVI (Normalized Difference Vegetation Index) is the near IR plus red divided by near IR minus red. Take a look at this image for the meaning of the colours – red, magenta and white is more photosynthesis, cool colours and black are less. Chlorophyll uses red but doesn’t use near IR which it reflects, hence the difference carries useful information.Lots more at Public Lab. Continue reading “Using near IR to look for photosynthesis and plant health with NDVI”

Canon EF 100-400 L lens fungus attack

note – this is a Mk 1 version of the Canon EF 100-400 L

A working photographer uses their lenses all the time and probably never runs into this. I was into bird photography for a while, about eight years ago, and had the Canon EF100-400 IS L like every other wannabe bird photographer. In between now and then the field has separated the sheep from the goats – real bird photographers use longer primes, because the birds are always at the long end of any zoom. Or they use astro scopes on manual focus 😉

Anyway, I take time out from birds and photography, because life gets in the way, and I stow the lenses in a relatively cold room. A couple of years back I figured I’d take some long lens pics, and get greeted by this

which makes me curse. Mainly on the front element, though a starting spot on the inner element, which is part of the IS mech. The inner part is magnified by the biconvex front element. The spotty crap is on the inside of the front element, the fine filigree round the edge on the front of the front element. Continue reading “Canon EF 100-400 L lens fungus attack”