Crater Floor Star Trails final

One of my earliest attempts at Star Trails was taken from this crater in Lanzarote last year. Then there was a high wind and quite a few clouds around. This time it was a crystal clear sky with little wind. Another difference was using the fisheye lens to get more of the Crater Rim in the image which I think gives a more dramatic look

This was taken from the floor of the crater Montana Cuervo near Masdache, Lanzarote. It is not as well visited as many places on the Island. It requires an easy 20 minute flat walk on a footpath from the road to the base of the Crater. Round the right hand side there is a great gash in the Crater wall permitting easy access to the crater floor. There are large numbers of rocks scattered across the Crater floor.

The images were stacked in Startrails.exe

There are 2 methods of taking Star Trail images, either one long exposure of 20 minutes plus or a lot of shorter exposures later blended together. The problem with the first is if something goes wrong such as a walker with a flashlight or condensation you can lose the whole thing so I went for the second. It would normally be very time consuming to blend all the pictures together but there is now free software available to do it for you at http://www.startrails.de/html/software.html

With the method of stacking together shorter exposures noise is not such an issue so I turned off the Cameras noise reduction settings. If these are turned on it doubles the exposure length as a second image is taken automatically of the same length for the noise reduction process. This also causes gaps in the Star Trails if multiple images are blended. Noise was corrected later with software.

The circular pattern is formed by pointing the camera towards Polaris the Pole Star near the Plough. As the Earth turns stars more above the pole do not appear to move as much as those more above lower latitudes. I had with me an HTC Android Smart Phone with the Google Sky App. This enabled me to locate the pole star while there was still light. The foreground comprises an HDR image taken while there was still light. With the Camera and Tripod locked in position the star trail images were taken later when the stars were out.

A little light from nearby towns shows at the rim gap and on the right. The lack of clouds makes this less obvious. Also I kept frames with some remains of blue in the sky which avoids any orange glow from light pollution..

The images used were taken over 1 hour 14 minutes with 37 images of 1 minutes 59 seconds  exposures each with 1 second gap between each exposure on the timer. These were stacked with the startrails software.

All the settings and equipment were as follows

- Sony A700 Camera.

- ISO 200, f3.5, 1 minute 59 seconds, 8mm.

- Long Exposure and high ISO noise reduction set to off. Otherwise the Camera would take One minute and 59 seconds between each shot for its own noise reduction resulting in great gaps in the Star Trails.

- Samyang Fisheye lens 8mm.

- Tripod.

- Interval timer

See this post for a review of this Timer

http://edwinjonesphotography.com/blog/2012/5/timer-interval-remote-review

Tips

- Arrive early, bring a compass or Smartphone, to help find the north star.
- Setup gear while it’s still light, get your composition and wait.
- Shoot test shots, make sure you can see the first stars.
- Wait for that perfect moment and then start the exposure.
- Bring a torch, so you can find you way and make adjustments after dark.
- Bring warm clothing and a snack and drink.

<b>Photoshop</b>

For the Star Trails the stacking software works on jpegs which are then saved as a Tiff.

After opening in Photoshop some extra detail was brought in with Topaz Adjust and Noise reduced with Topaz DeNoise.

The Star Trails were brightened with adjustments in levels, contrast and brightness.

Saturation magenta reduced to tone down the purple shade of the light pollution

After flattening the image duplicate layers were brought up to sharpen and then apply Topaz DeNoise again.

For the foreground this was a standard 3 shot HDR taken with light still in the sky with some enhancement in Topaz.

Adjustments were made to increase Vibrance and detail and sharpen.

On the Star Trails image I selected the sky using the quick selection tool. Then I copied the selection and pasted it in to the foreground HDR image. I used the move tool to line it up with the foreground.  Some pixel level cloning was done along the line of the join to remove some bright areas which came across from the foreground image

BEFORE AND AFTER

Below are the Before and After images. First the HDR image of the foreground after Photomatix but before other processing. Then the Star Trails Image after merging of the frames but before other processing and then the final result.

Tonemapped Foreground

Crater Floor Star Trails background tonemapped

Merged Star Trails image

Crater Floor Star Trails stars image

Final Image

Crater Floor Star Trails final

For licences see Crater Floor Star Trails

Edwin Jones