Starship Asterisk*

Star Trails and Tajinastes

Explanation: What bizarre planet do these alien creatures inhabit? It's only planet Earth, of course. In this well-composed scene, the sky is filled with star trails around the north celestial pole. A reflection of the Earth's daily rotation on its axis, star trails are familiar to photographers who fix their camera to a tripod and make long exposures of the night sky. But the imposing forms gazing skyward probably look strange to many denizens of Earth. Found on the Canary Island of Tenerife, they are red tajinastes, rare flowering plants that grow to a height of up to 3 meters. Hidden among the rocks of the volcanic terrain, tajinastes bloom in spring and early summer and then die after their seeds mature. On the distant horizon, below and left of the celestial pole, lies the Teide volcano.

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Sheesh -- its not bad enough the Apod picture of the day has me going around in circles, but when i clicked on red tajinastes - i got the Spanish version of Wikipedia!! I think this site is still in hang-over mode from the 15th Birthday celebration one tooooooo many root

how much faster would the earth have to spin in order for us to see this sky with the unaided eye?
happy 15th apod

Here ya go, beyond! http://en.wikipedia.org/wiki/Echium_wildpretii

http://en.wikipedia.org/wiki/File:Echiu ... LC0204.jpg
It's a rather pretty plant; kind of spiny though! I can see why the bees would like it.

Hey does anyone know how to take a photograph like this one? How long does it take? Can you use a Canon 40D or are there other things you need to make this image work? I would love to do it someday.
What a beautiful picture! The plants in the shot make it perfect!

-Thanks to whoever knows the answer to my question-

Hannah

Based on the length of the star trails (about 45 degrees), it looks like it was a 3 hour exposure. With digital cameras, quite often you can take multiple shorter exposures and "stack" them, but I never could figure out how you could stack star trail images without getting gaps in the trails. If anyone can explain that to me, please do.

You can definitely take an image like this with your 40D. The simplest way would be to get a shutter cable (one that can lock the button down), and lock it down for 3 hours. For an exposure of that length, you will need a really dark place no matter what aperture or ISO settings you use.

WildGuruLarry wrote:Based on the length of the star trails (about 45 degrees), it looks like it was a 3 hour exposure. With digital cameras, quite often you can take multiple shorter exposures and "stack" them, but I never could figure out how you could stack star trail images without getting gaps in the trails. If anyone can explain that to me, please do.

You can definitely take an image like this with your 40D. The simplest way would be to get a shutter cable (one that can lock the button down), and lock it down for 3 hours. For an exposure of that length, you will need a really dark place no matter what aperture or ISO settings you use.

Alright, thank you! I didn't think I'd get such an immediat response! Thanks! I will have to get a shutter cable. That's what I thought I had to do. I'm going campingin August, so that'll be perfect time to do it!

Can anyone tell me what that bright one is at lower left, and why it's fuzzy (like a seismograph) when none of the others are?

Transcribe what the author said of the movie today in Apod in Spanish for the curious trace left, "the stroke to the left is Venus, and finally makes some strange movements because of low clouds."

Owlice to the rescue again!! Yahoo! And might i enquire about the meaning of your new signature??

WildGuruLarry wrote:Based on the length of the star trails (about 45 degrees), it looks like it was a 3 hour exposure. With digital cameras, quite often you can take multiple shorter exposures and "stack" them, but I never could figure out how you could stack star trail images without getting gaps in the trails. If anyone can explain that to me, please do. :)

You can definitely take an image like this with your 40D. The simplest way would be to get a shutter cable (one that can lock the button down), and lock it down for 3 hours. For an exposure of that length, you will need a really dark place no matter what aperture or ISO settings you use. :)

You can't take a 3-hour exposure with a 40D, or with any DLSR. The dark current is too high, and the pixels will fill up from that and obscure any actual image. DSLRs give the best long exposure results for 5-10 minute images. An image like this is made as you first suggest- a lot of short images are stacked together. You do sometimes see star trail images that show gaps in the trails. However, newer DSLRs like the 40D are capable of writing an image so quickly that there is less than a second between the end of one frame and the beginning of the next. That's short enough to make gap too narrow to see in a wide field image like this (stars along the celestial equator only move 15 arcseconds in a second; nearer the pole it's less; this image has a scale of around 200 arcseconds per pixel).

I'd make an image like this at ISO 200 or ISO 400, with the lens reduced one or two stops from maximum (to reduce aberrations), and I'd use a smart cable release, that can be programmed to shoot a sequence automatically (an inexpensive Canon accessory). Then I'd stack the subframes in Photoshop.

beyond wrote:Owlice to the rescue again!! Yahoo! And might i enquire about the meaning of your new signature??

Bicycling, beyond, bicycling! I'm still slow, but faster than last year (yay!)!

Thanks, Leon! I thought it was Venus, but wasn't sure, especially with the wiggling!

Chris Peterson wrote:

WildGuruLarry wrote:Based on the length of the star trails (about 45 degrees), it looks like it was a 3 hour exposure. With digital cameras, quite often you can take multiple shorter exposures and "stack" them, but I never could figure out how you could stack star trail images without getting gaps in the trails. If anyone can explain that to me, please do.

You can definitely take an image like this with your 40D. The simplest way would be to get a shutter cable (one that can lock the button down), and lock it down for 3 hours. For an exposure of that length, you will need a really dark place no matter what aperture or ISO settings you use.

You can't take a 3-hour exposure with a 40D, or with any DLSR. The dark current is too high, and the pixels will fill up from that and obscure any actual image. DSLRs give the best long exposure results for 5-10 minute images. An image like this is made as you first suggest- a lot of short images are stacked together. You do sometimes see star trail images that show gaps in the trails. However, newer DSLRs like the 40D are capable of writing an image so quickly that there is less than a second between the end of one frame and the beginning of the next. That's short enough to make gap too narrow to see in a wide field image like this (stars along the celestial equator only move 15 arcseconds in a second; nearer the pole it's less; this image has a scale of around 200 arcseconds per pixel).

I'd make an image like this at ISO 200 or ISO 400, with the lens reduced one or two stops from maximum (to reduce aberrations), and I'd use a smart cable release, that can be programmed to shoot a sequence automatically (an inexpensive Canon accessory). Then I'd stack the subframes in Photoshop.

Hmm.... Ok. I have another question. How do you take an image like this:
http://masslessparticles.files.wordpres ... _usno1.jpg

Obviously very dark nights are needed...But how do you take it?

-Hannah-

Guest wrote:Hmm.... Ok. I have another question. How do you take an image like this: http://masslessparticles.files.wordpres ... _usno1.jpg
Obviously very dark nights are needed...But how do you take it?

The thing that makes an image like this tricky is that the sky exposure is long enough (a few minutes, probably) to require tracking. But if you track the sky, you motion blur the foreground.

The most common way to make an image like this is to composite separate sky and foreground images. I suspect that is what was done with this image, since there is a slightly unnatural looking boundary between the edge of the mountains and the sky.

Owlice, my guess was "running". But ya know - rideing a bicycle is kinda like running in place, except that you are moving.

Chris Peterson wrote:I'd make an image like this at ISO 200 or ISO 400, with the lens reduced one or two stops from maximum (to reduce aberrations), and I'd use a smart cable release, that can be programmed to shoot a sequence automatically (an inexpensive Canon accessory). Then I'd stack the subframes in Photoshop.

are there specific cameras that can be programmed like this? for example is it possible to take these shots with "Canon 500D" in the programmed way? because 40D's cable release is different from 500D's. there are two models for Canon 500D (RS-60E3 & RC-1/RC-5) which i doubt calling them smart --they can just trigger the shutter and lock it!

Amir wrote:are there specific cameras that can be programmed like this? for example is it possible to take these shots with "Canon 500D" in the programmed way? because 40D's cable release is different from 500D's. there are two models for Canon 500D (RS-60E3 & RC-1/RC-5) which i doubt calling them smart --they can just trigger the shutter and lock it!

I use the Canon TC-80N3 smart cable release. It works with all Canon DSLRs, but you need to make a little connector adapter to use it with the older models. I think it works without modification with both the 500D and the 40D.

Hi all, I'm a first time poster and a long time lurker. I've been admiring the APOD site for many years. It's a first do thing after checking my email. I used to check the Digg site some, but there wasn't much useful information coming from there. Mostly people calling each other Idiots and morons or complaining about something or another.
That's a beautiful picture today. Someone must really put in lots of effort to get a beautiful shot like that. I notice that the north star isn't quiet in the center. Is that because it's not exactly in the center in relation to the earth's axis or maybe because of the wobbling of the earth on its axis? Also there seems to be three or four star trails just outside of the north star. Is that another stars trail or is it the north stars own trail? Thanks.

moonstruck wrote:Hi all, I'm a first time poster and a long time lurker. I've been admiring the APOD site for many years. It's a first do thing after checking my email. I used to check the Digg site some, but there wasn't much useful information coming from there. Mostly people calling each other Idiots and morons or complaining about something or another.
That's a beautiful picture today. Someone must really put in lots of effort to get a beautiful shot like that. I notice that the north star isn't quiet in the center. Is that because it's not exactly in the center in relation to the earth's axis or maybe because of the wobbling of the earth on its axis? Also there seems to be three or four star trails just outside of the north star. Is that another stars trail or is it the north stars own trail? Thanks.

Polaris is not directly above the North Pole, so, yes, the bright white star trail is Polaris. The other dimmer, more yellow star trails are ... Hmmm, I don't know ...

Chris Peterson wrote:I use the Canon TC-80N3 smart cable release. It works with all Canon DSLRs, but you need to make a little connector adapter to use it with the older models. I think it works without modification with both the 500D and the 40D.

but i guess TC-80N3 would not work with 500D without modification. TC-80N3 is not mentioned among accessories for 500D in Canon's website; besides TC-80N3 uses "N3 Connector" whiles 500D takes "E3 Connector" (2.5-mm phone plug).
how can i make an adapter to connect N3 to E3 Connector? do you think it'll be ok if i just connect Tip, Ring & Sleeve of E3 to Expose, Common & Focus pins of N3?

Gee that was fast. Thanks, bystander.

Chris Peterson wrote:

Guest wrote:Hmm.... Ok. I have another question. How do you take an image like this: http://masslessparticles.files.wordpres ... _usno1.jpg
Obviously very dark nights are needed...But how do you take it?

The thing that makes an image like this tricky is that the sky exposure is long enough (a few minutes, probably) to require tracking. But if you track the sky, you motion blur the foreground.

The most common way to make an image like this is to composite separate sky and foreground images. I suspect that is what was done with this image, since there is a slightly unnatural looking boundary between the edge of the mountains and the sky.

Alright, thanks

-Hannah-
"When I see your heavens, the works of your fingers,The moon and the stars that you have prepared, What is mortal man that you keep him in mind, And the son of earthling man that you take care of him?"

bystander wrote:

moonstruck wrote:Also there seems to be three or four star trails just outside of the north star. Is that another stars trail or is it the north stars own trail?

Polaris is not directly above the North Pole, so, yes, the bright white star trail is Polaris. The other dimmer, more yellow star trails are ... Hmmm, I don't know ...

That region is about the only place where I can identify a few stars (using a star map), because the position is kinda clear with regard to Polaris.

1 - Polaris (α UMi); 2 - HD 5914; 3 - λ UMi; 4 - HD 107192; 5 - Yildun (δ UMi); 6 - HD 51802; 7 - HD 5848; 8 - HD 212710; 9 - HD 36905