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30 minute exposure [pics]

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Roland Wooster said:
OK, far south then. None the less, my real question is how did you
find a star that the earth's rotation is in linear axis with, and
thus shows up as a center point of the image which everything else
is rotating around?

Is it easier to achieve than I'm thinking and you just pointed the
camera upwards or are you an astronomer and knew what to aim for,
or are you extremely lucky?

Thanks,
Roland.
Click to expand...
I pretty much just point the camera due south. The earths rotation does the rest. I am no astronomer thats for sure, but I have seen it done by others. I would gues that someone on the equator could not get such an image???
 
I am normally a storm chaser and weather photographer, but the weather has abandonded us to a disturbingly topsy turvey winter of warm and dry, then cold and drenched, then warm and dry again. Its currently warm and dry so the camera gets pointed at the sky.

10 minutes at ISO200. Looking NW on a dark night, no moon Glow on horizon from distant city of Adelaide. Night sky reflected in the dam in the gully. Tree lit up by house 100 metres behind.



A 100% crop - clean and smooth



Another 100% from the shadows



The detail resolved is quite amazing considering the conditions. No noise reduction, just light sharpen using layer masks. Shot in RAW and opened in ACR.

Cheers,
Tim
 
What F stop did you do?
Timkat said:
We've all seen the star trails pics before but I thought I may do
it again by just releasing the shutter and letting it run out of
time all on its own 30 minutes later it had finished with the shot.
Another 20 minutes later the battery went flat in the middle of NR.
Anyway here is the result...



18mm, manual focus at infinity, f 3.5, 1800 seconds @ iso 400.
Image shot in raw, white balance was manually set in ACR. Did a
rather rough job in removing the CCD burn in CS2. No noise
reduction in post work, just smart sharpen (almost too much)
The trees were not visible with the naked eye but clearly enough
light pollution from the distant house provided illumination.
And for interests sake a 100% crop.



Cheers,
Tim
http://www.hillsrain.com
http://weather.saint.net.au/
Click to expand...
--
Mike L.

http://www.pbase.com/ferrari355/galleries

Minolta Dimage S404
Nikon D70
 
yeah I did like 20 Min at F3.5 and ISO 200 and my sky was blown out white.
Timkat said:
Christoph S. said:
...that the pic is not over-exposed with f 3.5 and 30 min.
Click to expand...
Possible for the trees?? But certainly not the skies IMO. You can
see the white haze of the milky way running through the centre of
the image. Bumping the ISO to 1600 and 1-2 min exposure on a dark
night and the milky way pops out in all its splendour!
Cheers,
Tim
Click to expand...
--
Mike L.

http://www.pbase.com/ferrari355/galleries

Minolta Dimage S404
Nikon D70
 
100% crop is noisy, but i guess thats expected. but i still love the overall capture. great work!
 
Yeah, that's why I thought you were far north, what I really meant was: far from the equator. I'm in California and if I point straight up I get an arc across the image, not a full circle. I will have to try pointing north from some mountain top so I get as little foreground in the way as possible and I might be able to get more of a full circle, although I doubt a complete one.

Roland.
--
Gallery at http://www.rolandwooster.com
 
I just got a 12-24. I wonder if I should return it and keep using my kit lens...I thought I'd need 12mm but 18mm seems plenty wide.

--
How can you shoot women and children?
Easy...ya don't stop down so much. Ain't photography Hell!
 
Point of clarification. For the Northern Hemisphere, the Earth's axis of rotation points almost directly at Polaris, or the North Star, located in the constellation Ursa Minor. It's one of the brighter stars in the northern sky, and the trick to finding it is to use the first two stars in the Big dipper, and run an imaginary line from the bottom of the "dipper", through the two stars that make the "front of the dipper" until you come across the first bright star, about two fist lenghts away. That is Polaris. Everything will appear to rotate around Polaris. The further south you go, the lower in the sky it will appear. In NJ, its about 1/2 way up from the horizon to straight up, or 42 Deg. Any star that is less that 42 Deg from Polaris will make a complete arc. Stars greater that 42 Deg away will dip below the horizon. In the Southern Hemisphere, there is no star as close to the Earth's axis, but, I believe, the Southern Cross is the closest approximation.
--
Bob LaPadura
 
I have yet to try this with a DSLR. I went through a phase where I did this frequently with an old manual SLR. Yours came out much better than I would have expected with a D70. Film is still the best in this areas due to its low noise and long exposure abilities. I have done these kinds of shots with the shutter open for hours. This looks very promising though as you really pulled off the effect.

The perspective is very different than I am used to. Since I live in the US, I am used to seeing Polaris in the center of the circles.

Is there any risk involved with this? Could pixels get damaged doing this kind of shot? I notice you said it died during NR. Was the battery fully charged when you clicked the shutter?

great job!

daniel
 
Cheers Daniel. There is little doubt that film is still very much king for this type of work. At least for now :-) I cannot see any way that the CCD would be damaged. The battery died during NR because I wa silly enough to not use a fresh battery. I do think that this compromised the final image quality though. I have found that long exposure shots are pretty much as smooth with NR as without. Its biggest advantage is removal of the "ccd burn".

I will try another 30 minute shot at iso 200 later on tonight and importantly a fresh battery! I have done ISO 800 for 18 minutes before without NR and the results were quite good and reasonably clean considering. What may work better is multiple short exposures stacked perhaps?
aut0maticdan said:
I have yet to try this with a DSLR. I went through a phase where I
did this frequently with an old manual SLR. Yours came out much
better than I would have expected with a D70. Film is still the
best in this areas due to its low noise and long exposure
abilities. I have done these kinds of shots with the shutter open
for hours. This looks very promising though as you really pulled
off the effect.

The perspective is very different than I am used to. Since I live
in the US, I am used to seeing Polaris in the center of the circles.

Is there any risk involved with this? Could pixels get damaged
doing this kind of shot? I notice you said it died during NR. Was
the battery fully charged when you clicked the shutter?

great job!

daniel
Click to expand...
 
Love the photos..I'm going to have to live till 100 to try out everything I see in the D70 group

If you have a minute take a look at this site it predicts where you can see satelites and their brightness. A few years ago i purchased a photo magazine where someone had captured flares from Iridium satellites ...

http://www.heavens-above.com/

Regards John Boyd
 
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