Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-03-2021, 09:27 AM - 1 Like   #16
Pentaxian
Michael Piziak's Avatar

Join Date: Dec 2013
Location: West Virginia
Posts: 2,409
Original Poster
QuoteOriginally posted by interested_observer Quote
The key to a good location is to keep the major light dome in the area to your back, and there by be pointing from a light area into a darker area.

Find Polaris - the north star and point at it (or just point to the north) and you will get actual star circles around Polaris.

Get a copy of Stellarium for your PC (its a free download) to show you where everything is. I think that it's about $10 for your smartphone, so that you can just hold your smartphone up to the night sky and it will overlay on the screen where all the stars are located. Also, Photopills ($10) on your smartphone will do that and more, especially well suited for the milky way shooting and planning.

Thanks for the tips. I went to the Stellarium website and was pleased to find out that it is available for LInux! I am checking out the web version of it now...

---------- Post added 10-03-21 at 09:29 AM ----------

QuoteOriginally posted by biz-engineer Quote
Looks like you had a earth quake while recording you first star trials images. Any injuries, I mean are you Ok?
LOL, yep we had a major quake! ha! I too would like to know what went awfully wrong with that exposure - and weirder thing is, that 2 photos came out of it!

---------- Post added 10-03-21 at 09:34 AM ----------

QuoteOriginally posted by Bob 256 Quote
You're getting there. As mentioned, a good stable tripod is best for long exposures like you're making. You can make very long exposures this way, provided your camera battery isn't exhausted in the process since the camera will likely draw current during the exposure. Some use a battery eliminator to make long exposures like you're doing. Try to focus on a bright star or planet before making the exposure to get sharp star trails.

You can get more detail out of some of your photos by post processing. Here is one with curves applied to it. You'll get the feel for these as you do more and experiment.

I think that bright spot in this one is the Orion nebula which you might take a closer look at with your telephoto zoom. You'll need a wide open short exposure to prevent blurring of the image if you do.

Thanks for the tips.

My tripod is a cheap one (an Amazon basics item). I did, however, stabilize it a LOT by hanging an 8 pack of sodas from the hook. With my tripod, I was actually more concerned with it tipping over in the wind than getting a shaky exposure....

The Orion nebula, eh? I thought it was merely a planet, which generally are my brightest stars in my photos in the past....

Thanks.....


Last edited by Michael Piziak; 10-03-2021 at 10:32 AM.
10-03-2021, 10:43 AM   #17
Pentaxian
Michael Piziak's Avatar

Join Date: Dec 2013
Location: West Virginia
Posts: 2,409
Original Poster
QuoteOriginally posted by Bob 256 Quote

You can get more detail out of some of your photos by post processing. Here is one with curves applied to it. You'll get the feel for these as you do more and experiment.
Yes, indeed. I did an auto-levels and got this result, which made it look like a photo taking during a sunny day....

10-03-2021, 12:20 PM - 2 Likes   #18
Pentaxian
ecostigny's Avatar

Join Date: Nov 2017
Location: Branford, CT
Posts: 549
QuoteOriginally posted by Bob 256 Quote
You're getting there. As mentioned, a good stable tripod is best for long exposures like you're making. You can make very long exposures this way, provided your camera battery isn't exhausted in the process since the camera will likely draw current during the exposure. Some use a battery eliminator to make long exposures like you're doing. Try to focus on a bright star or planet before making the exposure to get sharp star trails.

You can get more detail out of some of your photos by post processing. Here is one with curves applied to it. You'll get the feel for these as you do more and experiment.

I think that bright spot in this one is the Orion nebula which you might take a closer look at with your telephoto zoom. You'll need a wide open short exposure to prevent blurring of the image if you do.
Actually, the bright spot is the planet Jupiter, which is considerably brighter than the Orion Nebula. You can tell that this isn't Orion because there's no sign of Betelgeuse and Rigel, which are two of the brighter stars in the sky. Jupiter is in Capricorn these days, along with Saturn at the opposite end of the constellation.
10-03-2021, 01:04 PM - 1 Like   #19
Pentaxian At Large
Loyal Site Supporter
robgski's Avatar

Join Date: Nov 2012
Location: Shenandoah Valley, Virginia
Photos: Gallery | Albums
Posts: 7,084
There is a lot of experimentation in learning how to do this well.
Good news, you are getting star trails. Bad news, ambient light is blowing out your skies.

Try tilting the camera higher and avoiding that tree, and
You could also use a longer lens with a narrower FOV to limit ground clutter.

You are in WBGVa, you must have plenty of mountain roads and scenic overlooks with less light pollution.


Last edited by robgski; 10-03-2021 at 01:17 PM.
10-03-2021, 01:44 PM - 3 Likes   #20
Loyal Site Supporter
Loyal Site Supporter




Join Date: May 2007
Location: Flagstaff, Arizona
Posts: 1,252
QuoteOriginally posted by Michael Piziak Quote
which made it look like a photo taking during a sunny day....
How about this version, from a few minutes playing. With a vignetting correction, it could be made even more uniformly dark. As noted above, yes, indeed, that bright object is Jupiter. If you look closely at the top left of its trail, you can see the trail(s) of one or two of its moons.
Attached Images
 
10-03-2021, 08:19 PM - 3 Likes   #21
Loyal Site Supporter
Loyal Site Supporter




Join Date: Jun 2009
Location: Tumbleweed, Arizona
Photos: Gallery | Albums
Posts: 5,642
I took one of your test images and ran it through an online plating utility that identifies the area in the sky you captured and identifies all the stars and their constellations.

  • Astrometry.net - here are the results from the plating, providing all the data it was able to extract from your image (just not the exif data).
Here is a link to an article on the web about the color of the night sky. The guy is an astronomer. His website has about 50 articles on just about any topic dealing with astrophotography.One of the better general raw processing utilities that is good for astro is raw thearpee, which is available on Linux.

Last edited by interested_observer; 10-03-2021 at 08:38 PM.
10-04-2021, 05:36 AM - 2 Likes   #22
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 4,847
As you've just discovered, long-duration exposures of the night sky can be fogged. And although @AstroDave's post processing shows that it's possible to remove the background fog to create a dark sky, the fog does limit the visibility of fainter stars and thus

The longest possible exposure time (for a given ISO and aperture) depends on:
1) your camera sensor's dark current
2) the quantity of light pollution (city lights + moon light).
3) the quality of the atmosphere (humidity, haze, dust, smoke, etc.)

Issue #1 is something you can test in the comfort of your home. To do so, turn off long-shutter time noise reduction. Next, put the lens cap on, cover the viewfinder eyepiece, place the camera somewhere dark, and shoot a 1 hour, 2 hour, or whatever long duration image of absolute darkness. You'll find that even in pitch darkness, the image will have a speckled fogginess that gets worse with longer durations and at higher temperatures. Hard-core astrophotographers use cameras with chilled sensors and take special care to collect "dark frames" which are long duration test shots that record the pattern of the sensor's dark current and enable them to subtract that part of the image fog.

Issue #2 is the easiest to control but typically means driving somewhere that's very dark and then only shooting when there's no moon. Other's have posted a link to a light pollution map you can use to find suitable locations with less light.

Issue #3 is harder to control but websites such as Clear Outside (Clear Outside v1.0 - International Weather Forecasts For Astronomers ) can help you forecast the quality of atmosphere at your location to pick nights that are more likely to yield decent images. Clear Outside also gives International Space Station passovers and moonrise/moonset times.

Issues 2 & 3 aren't exact sciences so it's a good idea to try to measure the actual light pollution and haze conditions when you get to the site. One tip is to do a high-ISO test photo before doing a really long duration shot. Multiply the ISO you plan to use by 64 or increase the ISO by 6 stops (e.g., ISO 100 becomes ISO 6400) and take a shot where the number of minutes of exposure in the test shot equals the number of hours you plan for the real shot (a 2 minute high-ISO exposure provides a test for 2 hour low-ISO exposure). (Or you can do one with the number of seconds in the test shot equals the number of minutes in the planned shot: 45 seconds at high ISO simulates 45 minutes at low ISO). The point is to get a sense of the quality of the sky.


Have fun!

10-04-2021, 09:54 AM - 1 Like   #23
Pentaxian
Michael Piziak's Avatar

Join Date: Dec 2013
Location: West Virginia
Posts: 2,409
Original Poster
QuoteOriginally posted by ecostigny Quote
Actually, the bright spot is the planet Jupiter, which is considerably brighter than the Orion Nebula. You can tell that this isn't Orion because there's no sign of Betelgeuse and Rigel, which are two of the brighter stars in the sky. Jupiter is in Capricorn these days, along with Saturn at the opposite end of the constellation.
Thanks for the information and for verifying that it is Jupiter. I read that nebular can be either an area where a star had died/is dying or even an area where new stars are forming - do you know which is it that Orion is? Just curious....

---------- Post added 10-04-21 at 09:57 AM ----------

QuoteOriginally posted by robgski Quote
There is a lot of experimentation in learning how to do this well.
Good news, you are getting star trails. Bad news, ambient light is blowing out your skies.

Try tilting the camera higher and avoiding that tree, and
You could also use a longer lens with a narrower FOV to limit ground clutter.

You are in WBGVa, you must have plenty of mountain roads and scenic overlooks with less light pollution.
Thanks for the info....
I would use a longer focal length lense, but I'm currently kinda doing an experiment where I leave my 50mm lens on the camera for a week or so to discover things about the lens.
& yep, West By God Virginia (ie West Virginia) it is. A look at one of those light pollution maps quickly shows that our state is one of the less populated areas in the eastern U.S., so there are plenty of places to drive to, to attempt to capture star trails again. Smiles....
10-04-2021, 10:17 AM - 1 Like   #24
Pentaxian
ecostigny's Avatar

Join Date: Nov 2017
Location: Branford, CT
Posts: 549
The Orion Nebula is one of the nebulas that is a massive region of star formation; in fact, it's the closest big one to Earth. Of course, "close" is roughly 1,300 light years away, where a light year is 6 trillion miles.
10-04-2021, 10:28 AM   #25
Pentaxian
Michael Piziak's Avatar

Join Date: Dec 2013
Location: West Virginia
Posts: 2,409
Original Poster
QuoteOriginally posted by AstroDave Quote
How about this version, from a few minutes playing. With a vignetting correction, it could be made even more uniformly dark. As noted above, yes, indeed, that bright object is Jupiter. If you look closely at the top left of its trail, you can see the trail(s) of one or two of its moons.
Thanks for the post processing work - it looks very good IMO !
I did not know that applying vignetting correction(s) would result in this type of final image. Vignetting, in my mind, is the circular dark area around the edge(s) of an image, & I thought this type of correction would result in eliminating that dark area outside the circle...

---------- Post added 10-04-21 at 10:29 AM ----------

Thanks to all that replied. I gave each of you a green thumbs up!
10-04-2021, 10:30 AM - 1 Like   #26
Loyal Site Supporter
Loyal Site Supporter




Join Date: Jun 2009
Location: Tumbleweed, Arizona
Photos: Gallery | Albums
Posts: 5,642
QuoteQuote:
I read that nebular can be either an area where a star had died/is dying or even an area where new stars are forming - do you know which is it that Orion is? Just curious....

10-04-2021, 11:37 AM - 1 Like   #27
Loyal Site Supporter
Loyal Site Supporter




Join Date: May 2007
Location: Flagstaff, Arizona
Posts: 1,252
QuoteOriginally posted by Michael Piziak Quote
Thanks for the post processing work - it looks very good IMO !
I did not know that applying vignetting correction(s) would result in this type of final image. Vignetting, in my mind, is the circular dark area around the edge(s) of an image, & I thought this type of correction would result in eliminating that dark area outside the circle...
Depending on lenses and cameras, vignetting may or may not be particularly sharply defined. It is often, as in your image, fairly gradual for lenses on the cameras they were designed for (i.e. full frame lenses on FF cameras / APS-C lenses on APS-C cameras). Take your lens and shoot a uniformly illuminated surface (or clear sky on a nice day) at various f-stops and you should be able to see the effect.

All I did was adjust curves in Photoshop Elements. I was making the whole frame darker or lighter (I may have masked out the tree - I don't remember). There is some vignetting in your image which makes the corners gradually darker than the rest of the frame. If that is corrected (which various programs can do) by applying the inverse of the vignetting effect, then adjusting the whole frame uniformly would make it uniformly darker all over.
10-04-2021, 12:30 PM - 1 Like   #28
Site Supporter
Site Supporter
bobbotron's Avatar

Join Date: Jan 2015
Location: Ottawa, ON
Photos: Gallery
Posts: 3,255
QuoteOriginally posted by Michael Piziak Quote
ok, I finally got some results....
The camera definitely takes a while to complete the process, after the button is pressed the 2nd time to stop the exposure. After standing there and watching the little circular orange light blink for 2 to 3 minutes, I decided to walk upstairs and wait and come back later. When I came back, the light had stopped blinking. In the image, there is definitely light pollution coming off of lights on the back of the house. So I can see why people like to do this in the forest where there is absolute darkness. It's a Ultra 100 MB/s SD XC I card.

Image 1: Final result after about a 15 minute exposure. ISO 400 at F4. This is the only image I was shooting for. Not optimal, as in the future I want a lot of black in the image.


Image 2: Short exposure at ISO 1600 F4 - practice image take before image 1



Image 3: Short exposure at ISO 100 F4 - practice image taken before Image 1



Question: How long of an exposure can I take using this method?

---------- Post added 10-02-21 at 09:53 PM ----------



Thanks for the tips. As you can see from my post, I was able to get some result. I think ISO 100 would be appropriate considering the light pollution coming off the back of my house and other houses in the area...

I am using the IR remote to start the exposure (it waits 3 seconds after button is pressed to begin) and then use the remote to stop the exposure.

---------- Post added 10-02-21 at 09:56 PM ----------



I wasn't aware that heat was generated by the sensor. With my method, just one push of remote to start then one push of the button to stop, isn't there just 1 exposure?
Regardless, does heat become an issue on the camera?
For what it's worth, you're *almost always* going to have to post process astro photos. The photo above should be run through something like Lightroom, Rawtherapee, etc, to bring down the levels.

I'd say keep trying, you really need to do about 20 or 30 of these to get a feel for it.
10-04-2021, 12:34 PM   #29
Pentaxian
Michael Piziak's Avatar

Join Date: Dec 2013
Location: West Virginia
Posts: 2,409
Original Poster
Curious if these dots are celestial objects, or more likely are lens imperfections - ? some dots are dark colored on the blue image (that I didn't circle)...


As circled in images below. Click images several times to zoom in.



&



Perhaps best thing to test this is to take a photo at f4 against the sky or other background ?

Addendum: Just took these 2 images of daytime sky for comparison, at f4: https://www.flickr.com/photos/piziak/51550079907/in/dateposted-public/ *AND* https://www.flickr.com/photos/piziak/51550878586/in/dateposted-public/ (should have taken them at ISO 400 instead of ISO 100)

Addendum 2: These 2 photos taken at F4 & ISO 400: https://www.flickr.com/photos/piziak/51551141608/in/dateposted-public/ *AND* https://www.flickr.com/photos/piziak/51551815265/in/dateposted-public/

Last edited by Michael Piziak; 10-04-2021 at 01:31 PM.
10-04-2021, 12:58 PM - 3 Likes   #30
Loyal Site Supporter
Loyal Site Supporter




Join Date: May 2007
Location: Flagstaff, Arizona
Posts: 1,252
Those are what are called "hot pixels" - minor problems in the sensor (not lens). If they were celestial, they'd be streaked out like the rest of the stars/planets.

See Hot Pixels for some more info (or do a google search)
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
attempt, attempt at star, camera, card, exposure, f4, flickr, image, images, iso, k5, lens, light, michael, miles, noise, orion, pentax help, photography, polaris, release, results, shutter, star, trails, troubleshooting
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Night First Star Trail Attempt bertwert Post Your Photos! 2 01-18-2016 01:37 PM
Night First Star Trail Attempt jswillems Photo Critique 6 01-22-2011 03:21 PM
People A Dismal Day of Football deadwolfbones Post Your Photos! 11 12-12-2009 01:12 PM
My first star trail shot came out doubled? RollsUp Photographic Technique 25 11-25-2009 08:05 AM
My First Stacked Star Trail Photograph Christopher M.W.T Post Your Photos! 27 09-11-2009 09:40 PM



All times are GMT -7. The time now is 02:08 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top