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| Moderated by: chrisbet, | ||
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Robert
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Following on from some other night time outings I wanted to get a nice star trail photograph of the Ribblehead Viaduct and some other local landmarks. Last evening we headed off to Ingleton armed with the D3 and D300S, plus my large adapted surveyors tripod. My original concept was to capture the viaduct from near the road to the south of the viaduct but having set up and taken a few shots I decided the viaduct was far too insignificant in the images. Not wanting to have a prospective good cloudless night wasted we moved down to the viaduct and set up in a swamp. Very soggy conditions, with some quite deep pools of water all around. After some tentative exposures I took to 2 sets of images. This is a quick process from the second set, with reduced exposure. We had a visitor who trudged through to scene with a very bright torch, then back again... Using the Lightroom removal tool I erased the worst intrusions and some airplane trails, then exported JPEGS which StarTraX software used to create the image below. With the D3 and the 20mm Nikkor I was able to capture Polaris and the ground level scene. With DX the D300S can't get both, even with a slightly wider (and slower) 18mm lens. Nikon D3, Nikkor 20mm f2.8D, 20 seconds @ f3.3, ISO1600 exposures at 40 second intervals.  |
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jk
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Just need that train steaming or deiseling across. Very nice Robert. |
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Eric
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  Attachment: steam.jpg (Downloaded 24 times) |
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Eric
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Seriously though.....Really nice Robert. I suspect it's a lot harder than you make out.  |
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jk
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How many exposures Robert? Please can you post a single exposure image version. |
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Robert
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Eric, what can I say!  What a superb edit. The idea had crossed my mind but I never thought that a suitable train might exist. Well done. Thank you for the kind words. My shoes are gradually drying after their soggy night. Must take wellies next time. JK, I will dig out one of the frames and post later, I don't much count the frames, I tend to run a sequence for at least 30 minutes regardless of the frame rate, that seems to provide a nice length of trail. Currently with the D3 the interval between the start of each exposure is 40 seconds, I think the Riblehead exposures were 20sec @ f3.2, so the sensor had a little time to cool between exposures, I might experiment with lower ISO and a longer exposure? The software can fill the small gaps between the exposures. I have seen star trail photographs which must have been taken all night and the image is just rings of light which os OK if that's what you want but it's very difficult to make out the constellations or identify particular stars, except Polaris of course!!! I have been eying the Milky Way, last night it was quite distinct but I think I will have to find the darkest skies possible to get anything worthwhile. Thinking in terms of making a panorama across the sky with something between 100 and 200mm, although maybe the 300 f2.8 might be able to be pressed into service? Trouble is the sky is constantly moving in a circle and tracking it could be an issue without a big polar mount. Maybe I could make something... Need to get the lathe working and thinking cap on! LOL |
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jk
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Personally I dont like the star trails as it makes the highlights distracting, which is why I asked about the single exposure shot. My experience of this is with the Fuji. Shooting with the camera at ISO1600 for 20-40secs at f2.8 If you make a polar mount then be sure to document it well. I would attempt to make one here. |
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Robert
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jk wrote:Personally I dont like the star trails as it makes the highlights distracting, which is why I asked about the single exposure shot. OK no problem, I accept the stare trails can be distracting, I just feel they add an unusual dimension to the image and have novelty value purely from a pictorial point of view. I have shown people both and they usually react with more interest and enthusiasm to the star trail images than the plain star image single exposure. I also feel they allow the range of colours to be more visible, rather than just white dots. I have found you can extract a great deal more detail from each exposure but of course it also tends to increase noise perhaps internal camera noise and light pollution, it also seems to cause a lack of contrast due to the noise. More work needed... Maybe the NIK filters have a role here? The single shot is a bit more demanding in a way because it needs to be as short as possible exposure to reduce the elongation of the stars on the periphery of the radius from Polaris. 30 seconds is way too long if it's to be used for a single image mid radius I guess it at least double the diameter to streak length. There are chart's and calculators out there which give the ideal combination of shutter speed/focal length/minimum aperture. Yes, I will make lots of photo's of a polar mount. Changing tack slightly, I noted with interest in the D850 brochure some illustrations of the D850 mounted on a slide rig formed with a tripod and a large rock! I am trying to devise a slide rig to add linear motion to time lapse photography. Getting slow, smooth controllable linear motion is a bit of a challenge. I was interested to note that the rig in the D850 brochure appears to have wheels running on tube rails for the mount to slide along. I envisage adapting a cross cut saw slide mechanism with longer rails... The cost of this gear to buy 'the proper thing' is colossal. I'm sure it can be created from skip salvage bits and pieces. A car window winder motor would provide a simple motor which could be driven with a timer pulse feed to inch the head along the tracery slowly over some hours. |
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Robert
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jk wrote:How many exposures Robert? 44 images used to make that star trail picture at 40second intervals which according to my calculations is 29.3 minutes duration! Not bad for a guess... Here we go, I have done a little more processing on this one just to pull out a bit more detail, the processing of the star trail batch was slanted towards uniformity for the batch but this one is aimed to get the best (I can) from a specific image. Same exposure details as the star trails image above.  This is a 100% crop from the same image (one image pixel to one screen pixel), centred on Polaris, same processing.  |
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jk
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Nice pictures. Thanks for posting. |
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Robert
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My pleasure. Should have a set from the D300 soon when I get them processed. Any idea what that jumble of pixels under Polaris might be? Could it be CA? The lens is my Nikkor 20mm f2.8D AF @f3.2. |
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Robert
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Last night went to Cartmel. The Priory is a very distinctive landmark which is very prominent in the village centre. Over the years I have worked on the structure of the priory several times, from the drains to the belfry and leadwork on the roof, I even helped install the 'new' Organ back in the sixties. So I know Cartmel Priory pretty well. This is our second batch, the first batch was dominated by too many trees. The batch contains 54 exposures. I was a bit troubled by passing cars lighting up one tree which looked wrong so I chose a nice exposure and layered it to obscure the bright tree. Nikon D3, Nikkor 20mm f2.8, F3.2@20seconds, ISO 1600.  Specially for JK one chosen exposure without the star trails.  |
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Robert
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Just for interest, this is the output from the StarStaX software which I used to create the star trails. I wasn't happy with the brightly lit tree or the red light by the Cromwell door of the Priory. The tree had been lit by several passing cars while I was making the star trail stack exposures. The red light was me showing Christopher the bullet holes in the door made by Cromwell and his men when they attacked the priory in about 1645 during the dissolution of the monasteries. There are bullet holes which burst through the heavy oak door and can be plainly seen. I layered a much cleaner image over the star stack image and cut away to reveal the star trails and other bits that were good.  |
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