New Birmingham image gallery after recent trip

    Selfridges Store - Street Entrance
    Selfridges Store – Street Entrance

    Last Wednesday a group of us from Tetbury Camera Club made a visit to Birmingham (England not Alabama!) for the purposes of some photography. We organise regular photography trips within striking distance of Tetbury, including quite a few to London, but this was our first time to Birmingham ensemble. I used to work in Birmingham and so it had been reasonably straighforward to devise a route taking in the best bits of the centre of town. But it was ten years ago that I last ventured into Birmingham and a lot has changed since then – for the better – notably the construction of the splendid new library and the increase in the pedestrianisation of the streets in the centre. Birmingham, motown of the Midlands, had finally all but banished the motorcar from the centre of town – and what an improvement.

     

     

    The highlights of the trip were:

    1. Selfridges and the Bull Ring
    2. Snow Hill area
    3. Cathedral Green
    4. Victoria Square
    5. Council House
    6. Town Hall
    7. Centenial square showing library etc.
    8. Library Roof for a panoramic view of the city
    9. Malthouse Wharf area
    10. Gas Street Basin – aerial tour – click here
    11. The cube – aerial tour click here

    I have started a new gallery devoted to images of Birmingham. We will be going back
    soon for another session.

    Landscape Astrophotography

    avebury-1
    Communing with the Heavens – 26s, ISO1600, f2.0 Sony NEX7 and Samyang 12mm

    Last Friday I tried my hand at some Landscape Astrophotography at the ancient stone circle at Avebury. I went with a friend from Tetbury Camera Club – safety in numbers in the land of Druids! Friday was a new moon and being July the Milky Way was high in the sky. Both of us had recced the scene in the daylight and had some specific POVs in mind. But neither of us could be sure how dark it would be.

    Avebury is on the edge of the Salisbury Plain dark area, but quite close to Swindon and Calne besides having its own small group of houses and a pub in the village. As it turned out the Milky Way was visible but I would say not stunning. Good enough for an atmospheric shot of the stars and the old stones. The sodium light from Swindon and Calne dominate the horizon, and do tend to wash everything with a sodium light cast even where to the human eye it looks dark – the camera sees it all.

    I was using my Sony NEX7 with a Samyang 12mm manual focus lens. I had already checked to see where the point of infinity focus was on the lens focus scale and had checked that the lens resolved point light sources as such, so I was reasonably confident that I had tha basic kit. The high ISO performance of the NEX7 is pretty good and I do use ISO1600 for interior work and it cleans up OK. I had even purchased some chemical hand-warmers which I had ready in a sock to attach to the lens if condensation looked like being a problem, but there was no need for that.

    Using the so called rule of 500  I would be able to shoot at 28 secs while maintaining the appearance of reasonable point sources for the stars. Anything over that, the theory says, will produce visible short lines instead of points. The rule of 500 works like this: you divide 500 by the full frame focal length of the lens and that’s your max shooting time. So for my Samyang 12mm, that is the full frame equivalent of  an 18mm lens: 500/18 gives approximately 28secs. I have read that 400 is a more practical number which would give 22 secs. I opted for 25secs at f2.0 and ISO1600, which has produced a reasonable result, perhaps slightly on the dark side. You can see though, that the shorter the focal length, the better. A 50mm lens on a full frame camera would give only 10 secs using 500.

    What I was not prepared for was the difficulty of composing the image in very dark conditions. The NEX 7 has an EVF and it could see nothing! Even Matt with his D800 and its OVF said he was struggling to compose his images (they looked pretty good to me!). It was a matter of shooting blind, reviewing the result, adjusting the camera on the tripod, repeating the process until an acceptable composition was achieved. Getting everything just right was still almost impossible but the advantage of a wide angle lens and 25 megapixels is that there is plenty of scope for cropping! To speed the composition process up I used a much higher ISO and shorter shutter time.

    Taking the image is just the beginning. It takes a lot of careful processing to extract the detail from the image, and to get rid of the inevitable high ISO noise. I used Topaz Denoise, which does a very respectable job.  Even with the camera’s “in camera noise reduction” turned on, you are going to get noise, though presumably the camera has done away with any hot pixels.

    The finished image above, was the result of processing in Lightroom (mainly) with Topaz Noise reduction and the Topaz Detail  (preserve highlights preset). I am still experimenting with the processing and trying to find the ideal compromise between low noise and sharpness of image – not there yet!

    I am looking forward to some more experimentation with the camera too. I need to perfect the art before my holiday next year to the USA where we will be visiting some truly dark places! On my list to try out is the concept of taking multiple images and using the Photoshop median filter to remove noise. I have seen this technique demonstrated on the internet and it looks good.

     

    Curved Reflections on Water – An Explanation?

    On a recent trip to Canary Wharf with fellow photographers from Tetbury Camera Club for some night photography, we spent some time at Millwall Dock photographing the reflections. When we got home and started processing the images we were looking at curved reflections that seemed to bear no resemblance to what you would expect to see. Here is an example. Some were much more pronounced than this one. Some curved to the left, some to the right.

    Curved Reflection
    Curved Reflection in Millwall Dock, Isle of Dogs

    In searching for reason for these curved reflections there were no plausible explanations on offer until it came up in discussion with Jim who provided an answer after just a few seconds of thought! And after a lot more thought on my part and with the aid of some pencil sketches I came to the conclusion that he is right.

    First of all, this is what it is not…. anything to do with the the lens, or the mirror (mine is a NEX-7 which is mirrorless!).  It is all to do with the reflection of light off the surface of the ripples being blown across the water surface.

    Look at the image above and you will see that the reflections are not representative of the illuminated scene but are reflections of the lightest parts of the scene smeared in a band vertically across the water surface – the obvious examples are the cyan colour of the JP Morgan sign and the purple colour reflected from the horizontal lights on top of the building to right of centre.

    The image above  is an HDR fusion image from individual shots ranging from 0.25 to 15 seconds – some  long exposures. So within the exposure time of the images making up the water we would expect the ripples being blown across the surface to have travelled many centimeters.

    So what is happening. If we take the simple example of waves moving towards the camera and think of a wave as being a mirror we can see how the reflections are smeared by reference to the diagram below. At the point where the wave is flat (A) – at its peak and the bottom of the trough – you should see the normal reflection as if the surface was a mill pond. The leading surface of a wave will reflect light into the camera lens and the trailing surface will also reflect light into the camera lens and here is where the smearing occurs. What I think is happening is that the very bright lights – say the JP Morgan sign – overwhelm everything else above and below. So on the water surface beyond where the reflections of the letters would be for a dead calm surface we see reflections off the leading surface of the ripples (C). And conversely, closer to the camera we see reflections from the trailing surface of the ripples (B). Because the ripples/waves are marching across the water the reflections are merged together and the brightest light dominates. If the ripples are going away from the camera then swap trailing surface for leading surface. The whole effect is accentuated by the long exposure.

    Diagram Smeared Reflections
    Diagram showing how the reflection is smeared by the surface ripples on the water.

    So far so good, but what about the curve? That is explained by the fact that the ripples are not marching directly towards or away from the camera but are at an angle. Depending on the orientation angle of the ripples (which way the wind is blowing), and the position of the camera relative to the subject, the reflection will appear to curve to the left or to the right. So in our case, if my theory is correct, the wind is blowing the waves in a direction that is from near left to far right or far right to near left. Which direction, forward or back, does not matter (just the orientation) but for the sake of this explanation I am assuming far right to near left. In this case the rear edge/surface of the wave is acting as a mirror at an angle and reflects light that should be heading to the left of our camera back into our lens making it appear to come from somewhere to the left of where it should be. And by the same reasoning where we would expect to see a reflection on the right side of the vertical band of light, the rear surface of the ripple reflects the light away from the lens making the water appear dark. If the ripples were orientated far left to near right the reflection would curve to the right.

    Curved Reflection
    Diagram showing how reflection is curved

     

     

    Here is the un-cropped, unprocessed 0.25 second exposure shot with the exposure turned up in Lightroom so you can see what is happening on the surface of the water; and you can see the direction of the ripples on the water surface, running far right to near left as expected.

     

    reflections curved to left
    Reflections curved left showing ripples orientated far right to near left

     

    And below you can see the opposite effect to the one above, with the curves running the opposite way,and the ripples running the opposite way too. QED? I hope so!

    Curved reflections to right
    HDR image of Millwall Dock with reflections curved to the right this time.
    curved reflections
    Here is the shortest  un-cropped exposure of the HDR set with the exposure cranked up in LR to reveal ripples running far left to near right – exactly as predicted.

What’s it all about?

Here are my jottings about my photographic projects and activities. I have been working on a focus stacking macro photography rig. There are quite a few posts about that. In addition I write about other photographic activities as and when!

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