Read this and weep - Pentax GPS + more

[bakubo]

Image stabilization so sophisticated that it compensates for the rotation of the earth. Nice.

Probably it doesn't do it perfectly or maybe not at all, but the Pentax IBIS can shift up/down, left/right, and can also rotate. I don't know if the rotate part is useful for this application or not. I think the Sony IBIS can only shift up/down and left/right.

[pakodominguez]

Sometimes a small bombshell is dropped by a minor company doing something no-one thought of. Pentax clearly thought of something a VERY long time ago and built it into their K-5 and K-r models. Look at the Astrophotography function...

This is a common practice in the videogames world, where once in a while, some savvy post a new trick on a specialized forum... and the charm of an "old" console come back. People were expecting the same from the Alpha division, but I think the time a Sony (and others makers also...) camera is on the market is not long enough in order to follow this approach -other than the V4 on the A700 or the last upgrade on the A850/A900...

[bossel]

How many of us track stars? Cool technology, but of no use for most normal users

[bakubo]

How many of us track stars? Cool technology, but of no use for most normal users

Probably anyone who is not interested in this would be better off not buying the O-GPS1 accessory.

[bakubo]

I did some searching trying to find exposure guidelines for night sky photography. I didn't find anything too specific, but what I found would indicate my earlier guess is probably about right. Everywhere said to experiment with exposures and that is what digital is good for. As I mentioned already though, a dark sky is important with little or no light pollution. Probably the darkest skies I have ever seen were in parts of Africa and in West Papua, New Guinea.

By the way, I read a hint that sounded interesting. It said that the stars would just be pinpoints and those don't show color well. The hint was that from time to time during the long exposure to change the focus so that the stars are oof for a few seconds and then go back to in focus. It said that the result would be that the different star colors would show up much better.

[Javelin]

a lot of the time when your shooting star fields the photographers are shooting multiple exposures and stacking thats why theres not a lot of exposure info around. this is the way most beat the noise generated from long exposures

[Greg Beetham]

Here is a free stacking program, I haven't used it myself. There is quite a lot of info about astrophotography on the site. http://deepskystacker.free.fr/english/index.html
Greg

[bakubo]

We have all seen wide angle night sky photos with the sky full of stars and trees, rock formations, cactus, etc. in the foreground. With a tracking mount or this new Pentax function the stars may stay sharp with no trails in long exposures, but the foreground object would be blurred. It seems that even shorter exposures with stacking wouldn't work well in this case either since as the earth rotates and stars change their positions the camera would have to be moved. So, I wonder how do people make those sorts of photos with a foreground and sky full of unstreaked stars? I suppose it can be done with a single exposure that is long enough to capture a whole bunch of the stars yet not long enough to make obvious star streaks. I don't know when I will be in a place with really dark skies again with a tripod, but whenever that might be I will give it a try.

I found some example photos on Google images. This first one seems to have just a bit of star streaking in the outer areas.

night-sky-over-church-800.jpg

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[Greg Beetham]

I just took a couple from the backyard, just for fun, there is a bit of light pollution coming from the side in one and from behind in the other. I might have overdone the ISO at 3200 and/or the exposure might be better at 10sec maybe or drop to ISO1600 and expose for 20secs, hard to say, but I reckon stacking would be the way to go in any case as these aren't too wonderful.
Greg
ps. Henry those pix with stars and earthy bits would be high ISO perhaps and just the right amount of exposure, I can't guess how else it could be done offhand.

KM5D KM24-100
The Cross (upper left) and Eta Carina (unstable star, middle-ish)

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I put Omega Centauri (giant ball of stars) down at the bottom right in the hope of also getting Centaurus A (galaxy) in the shot but it might be a bit faint for that, or I need darker sky, or my 10" telescope

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[Birma]

Interesting shots you found Henry.

I like the variety of colours in your shots Greg. The first really does look like the "final frontier". Much to much light polution where I live in the UK for this kind of thing - will have to wait for trips away to try anything like this.

[Greg Beetham]

Hi Birma and thanks, one thing that I am amazed at is the amount of faint stars I got that I couldn't see with the naked eye. There is also a very large amount of tumbled nebula and dark patches of dust all across the Eta Carina area, so it would be nice to be able to photograph it properly, I'd say I'd definitely need dark sky out away from the city area to stand a chance of getting that faint nebula well depicted in the shot.
Greg

[bakubo]

Greg, those are pretty good.

I found some Pentax photos using this new function:

http://www.pentax.jp/japan/products/o-g ... racer.html

In particular notice the last 2 (off, on). When it is turned on the stars aren't streaked, but the foreground is blurry. When it is turned off it is the opposite. Completely expected, of course.

[Greg Beetham]

Thanks Henry, I spent most of the morning trying to match up any of my star atlases with those Pentax photos to try and find what parts of the sky are depicted in the wider views, in the end I had to admit defeat on that one. I thought there was Corona Borealis in there but the surrounding star pattern didn't match so now I don't know where it was, I also looked at the Pisces and Cetus areas but no luck...I have to imagine it upside down as well so that makes it a bit more difficult.
That Pentax gadget looks like it works quite ok even at 300sec and that's pretty amazing, also the amount of noise at 300sec I would have thought would be amazing as well but the image looks very clean. There are some minor edge aberrations but those could be lens related more than tracking related.
Greg

[Javelin]

subtracting a dark frame would still work to get the noise out i think

[Winston]

I found the first article on this page interesting.