The Big Dipper

[Nicks Pics]

I was intrigued to try some star photography by some very interesting astro-landscape photography Iv'e seen occasionally. I only used 3 sec. exposure, so it ended up looking pretty natural. I found this one to be a bit of an unusual task in editing, but I suppose I could have taken several different approaches.

[Wayland]

There is a very good rule of thumb regarding astro exposures which I find useful.

Start with the number 500* and divide it by the full frame equivalent focal length of the lens you are shooting with.

The resulting number gives you the longest shutter speed you can use before seeing significant movement of the stars in your frame.

For example: If you are using a standard 50 mm lens on full frame. 500 divided by 50 gives you 10 seconds. Simple.

On a sensor with a 1.6 crop factor that 50mm would of course be the equivalent of an 80mm on full frame. So 500 divided by 80 gives you 6.25 seconds in that case.

*(Some me people use 600 as a starting figure which gives slightly more generous settings but I prefer to stay on the safe side.)

[Nicks Pics]

There is a very useful rule of thumb regarding astro exposures which I find useful.

Thanks for giving this informative tip. I don't know what the equivalent crop factor of my sensor is, but I imagine it is fairly small, because I'm using a bridge camera; however, I think I can grasp the general point of the tip being that the magnification increases the effect of movement, so as it increases, the exposure time must be proportionately decreased._?

[Wayland]

Yep. That's about the gist of it.

You might find the crop factor in your instruction book or it might give you the "equivalent" focal lengths in the specifications.

[Shadowman]

Looks good from a distance, silhouette really adds to the imagery. Full screen shows lots of noise and as Wayland pointed out, out of focus stars from either camera movement or too long of an exposure.

[JBW]

The double star in the handle is a standard test for how good the 'seeing' is. In your shot it is hard to tell that it is a double. Was it a so-so night or a too long exposure?

[bnnrcn]

Nice effort Nic. I like the silhouette

[Nicks Pics]

Thanks everyone. I think the image quality decreased some in the downsizing. Now I see blocky color transitions in it, which I didn't see in the version on my computer.

The double star in the handle is a standard test for how good the 'seeing' is. In your shot it is hard to tell that it is a double. Was it a so-so night or a too long exposure?

Thanks for pointing out the double star. I can see they are a little blurred together. The camera was probably not completely still. The night was pretty clear, as I recall.

I would think that a long exposure would be desirable for star photography so that the sensor can soak up more of the light from the stars, perhaps more than one can usually see with their eyes. But maybe this can also be the cause of problems related to the image.

Full screen shows lots of noise...

There was a ton of noise in this image, but I also wanted to sharpen the stars and not loose the distant ones, or blurring the pine needles on the silhouette.

[HaseebM]

Nick I am happy to see your image, very few seem to post astronomy images here and I am a keen astrophotographer myself though due to my city light pollution, my images are mediocre at best. I have taken images with both a still tripod and 50mm lens as well as camera piggy-backed on a telescope which gives me greater control over duration to avoid star trails. Professionals use Equatorial mounts which are aligned to the North star and then calibrated with stars in their area of the sky. With the help of auto-guiders, they can shoot exposures of more than 10 minutes without stars trailing.

Hint: Try aiming your camera towards the star Antares ( bright orange ) which is towards South and take exposures of around 30 x 3 secs. Then combine them and you will be surprised at how well it turns out. You need to download freeware called Deep Sky Stacker which is excellent for stacking images.

Here are couple of examples:-

Orion nebula at 70mm.



M 41 open cluster.

[Nicks Pics]

Nick I am happy to see your image, very few seem to post astronomy images here and I am a keen astrophotographer myself though due to my city light pollution, my images are mediocre at best.

Thanks very much for giving me some ideas on astrophotography. Astrophotography isn't generally my main focus (pun) , but I was eager to try it some having seen some very interesting images, and am eager to try again. My camera has the potential for 1200 mm equiv. focal length, but at the longer lengths, I had trouble finding any stars for my camera to focus on. So I went for a more earthly view-this time.

Perhaps combining images, or layering really would be the best way to get good results in pp with astro-images.

You have neat images. I am surprised how many stars could be seen at only 70mm., though that is quite a bit of magnification. Taking photos through a telescope is an interesting idea. I've seen it done with binoculars, (not with very good results though)

You should get out of town some, if you can, if you have light pollution where you are, and take some pictures you don't think are mediocre.

[HaseebM]

Thanks Nick, those images were taken with a camera lens only. I also take images using telescopes and the results are even more interesting. Too bad though I cannot expose long enough to bring out details in objects like Andromeda or Rosette nebula etc., For comparison, here's the same image of Orion nebula taken through a 102mm Refractor.



Since this is an Achromat refractor, I can do very little for chromatic aberration. Hope you like it though. Btw, M42 Orion nebula is perhaps the easiest and most photographed celestial object aside from the Moon and Planets.

[Wayland]

I've been getting increasingly interested in combining astro shots with landscapes. It seems like the technology has come of age recently.



Just had some news that this one has been short listed for this years "Landscape Photographer of the Year" so I've got my fingers crossed that I might get into the book again.

This was twenty seconds f/4 6400 iso. With a 17mm on full frame.

[Mark von Kanel]

I've been getting increasingly interested in combining astro shots with landscapes. It seems like the technology has come of age recently.



Just had some news that this one has been short listed for this years "Landscape Photographer of the Year" so I've got my fingers crossed that I might get into the book again.

This was twenty seconds f/4 6400 iso. With a 17mm on full frame.

Did you paint the foreground with light?

[Wayland]

There was a half moon near the horizon to my left which provided all the light I needed for the stonework although it was a bit low for the grass.

It also threw some light into the sky which explains why it is a bit blue. The warm glow near the horizon is light pollution from Aberdaran to the SSE.

[IzzieK]

So how many shots did you take from this for the final presentation? Just curios...

There was a half moon near the horizon to my left which provided all the light I needed for the stonework although it was a bit low for the grass.

It also threw some light into the sky which explains why it is a bit blue. The warm glow near the horizon is light pollution from Aberdaran to the SSE.

[dabhand]

Nik,

It's also worth remembering that in the Northern hemisphere stars rotate counterclockwise around the zenith (essentially Polaris aka the North Star) and that the closer a star is to the zenith, the slower it will appear to move - down by the horizon it will fairly zip along (relatively).

steve

[HaseebM]

Excellent image Wayland. My fond wish is to one day see the Milky Way.

[Nicks Pics]

Hi Haseeb, Your image of the nebula looks like it could have been taken from outer space. That telescope-camera combo seems to work pretty well. Thanks for sharing.

Wayland, Astro-Landscape landscape photography is really interesting. I was attempting/would like to attempt that.

Steve,
Thanks for pointing out how the stars would rotate less around the North Star. Though I didn't have a long enough exposure for that to probably make much of a difference this time. In certain instances, Iv'e seen star rotation captured on purpose in images, but you wouldn't want that unless you were doing it on purpose.

[Wayland]

So how many shots did you take from this for the final presentation? Just curios...

I took a lot of frames as usual, (Hard drive space is pretty cheap these days, fuel for return trips not so cheap.) but this image was built from just three of those frames.

The main frame was pretty good on it's own but I aligned and used the other two on layers blended to darken to clean up some of the noise in the sky.

[Nicks Pics]

The main frame was pretty good on it's own but I aligned and used the other two on layers blended to darken to clean up some of the noise in the sky.

So did you not need more than one image to make that general appearance, apposed to using HDR, or something like that?