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10-02-2021, 07:20 PM   #1
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My dismal first attempt at star trail(s)

Asahi Pentax M-50mm macro f4 with k-s2 with tripod & remote (IR). Lens set to F4. ISO 100 on one image and ISO 400 on the other.


My dismal first attempt at star trail(s). I don't know how I ended up with 2 images though. Photo begins at 3 seconds after remote button is pushed and left open for 45 mins to an hour.

Back porch is a little bouncy that image(s) were taken from.

Oh well, it's my first attempt. It's very cloudy also, so only the 1 planet is prevalent.



&




Click on image several times to zoom in - not that it matters much. Comments please

Going to go down to a concrete ground and try again right now.

10-02-2021, 07:29 PM - 1 Like   #2
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I'm confused why only one 'star' in the picture and its orbital spin bouncy porch or not.
10-02-2021, 07:37 PM   #3
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QuoteOriginally posted by tuco Quote
I'm confused why only one 'star' in the picture and its orbital spin bouncy porch or not.

Well, only a few "stars" are visible - it's overcast.

I'm taking another long exposure right now - this time from a concrete porch at the ground level. After about 30 to 45 mins I'll see what happens and post the image back to this thread.
10-02-2021, 08:44 PM - 2 Likes   #4
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Well, I would suggest trying....
  • ISO - 400 to 800, start off high and adjust. Perhaps go as high as 1600. With my old K5, ISO 800 was a stretch, 1600 better. I've gone as high as iso 4000 with my k5 and captured good results
  • Aperture - Go with your fastest lens - if f4 is it, then start with ISO 1600 to compensate.
  • Exposure - I would put the camera in manual 30 seconds, then set it for continuous and lock down the external shutter release. Then stack the results (see the links below) No external shutter release, then I would then suggest Bulb and 20 minutes should be more than enough for good star trails.

Here are some good links...



Last edited by interested_observer; 10-02-2021 at 08:50 PM.
10-02-2021, 08:53 PM   #5
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Hmm,

On my second attempt. I pressed the remote again to stop the exposure. The light on the camera's back flashed for about a minute or less - I suspected it was processing or saving the image.
Anyways, Got the SD card into the computer, and there is no image saved to the card at all.
Hmm....



---------- Post added 10-02-21 at 08:54 PM ----------

QuoteOriginally posted by interested_observer Quote
Well, I would suggest trying....
  • ISO - 400 to 800, start off high and adjust. Perhaps go as high as 1600. With my old K5, ISO 800 was a stretch, 1600 better. I've gone as high as iso 4000 with my k5 and captured good results
  • Aperture - Go with your fastest lens - if f4 is it, then start with ISO 1600 to compensate.
  • Exposure - I would put the camera in manual 30 seconds, then set it for continuous and lock down the external shutter release. Then stack the results (see the links below) No external shutter release, then I would then suggest Bulb and 20 minutes should be more than enough for good star trails.

Here are some good links...

Thanks for your reply!
I will use your tips as I try a third time now...

Addendum: I just put the card back into the camera. I have a fully charged battery. The light on the back of the camera just keeps flashing and I can't get the camera to turn on. Hmmm....
Addendum 2: Took the battery out and reinserted it and it's good to go again... Formatted the card in camera... Here we go for a 3rd try with "interested observer's" tips
Addendum 3: I was thinking that instead of taking a bunch of pics (continuous picture taking?), that instead of that, then simply taking one long picture (exposure) would do the job. But I will try that method later also...

Last edited by Michael Piziak; 10-02-2021 at 09:16 PM.
10-02-2021, 09:08 PM - 2 Likes   #6
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Disable all of the additional image processing items. They are probably delaying the saving of the image. Image save should be pretty immediate and fast.

I added a couple of thoughts to the initial post. Don't be afraid to up the ISO to start to get something. If you are using one shutter push to open and then a subsequent second shutter release to close, put a hat over the lens to block the light just before the second push. Also use a 2 second delay.
__________________________

I would start with 5 minutes - you will get star trails but not really long ones. This would be a good test period rather than waiting 20, 30 40 or an hour. Get everything working and then go for a 20 minute duration.


Last edited by interested_observer; 10-02-2021 at 09:13 PM.
10-02-2021, 09:35 PM - 1 Like   #7
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Plus remember that for a 45 minute exposure your camera needs to do another 45 minute exposure with the shutter closed to create a dark noise exposure to subtract from the first exposure to remove noise due to the heat generated by the sensor while the shutter was open for the first 45 minute exposure.
\
This may explain why in your second trial there was no resulting image as you had not allowed the camera to do the second exposure to then subtract the noise.

Regards

Chris

10-02-2021, 09:38 PM - 1 Like   #8
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And as is obvious from your photo, you *must* ensure that there is no movement during the exposure. Since you have point source lights to deal with. any movement of the camera/tripod will result in squiggles rather than star trails.
10-02-2021, 09:43 PM   #9
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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 ----------

QuoteOriginally posted by interested_observer Quote
Disable all of the additional image processing items. They are probably delaying the saving of the image. Image save should be pretty immediate and fast.

I added a couple of thoughts to the initial post. Don't be afraid to up the ISO to start to get something. If you are using one shutter push to open and then a subsequent second shutter release to close, put a hat over the lens to block the light just before the second push. Also use a 2 second delay.
__________________________

I would start with 5 minutes - you will get star trails but not really long ones. This would be a good test period rather than waiting 20, 30 40 or an hour. Get everything working and then go for a 20 minute duration.

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 ----------

QuoteOriginally posted by seventhdr Quote
Plus remember that for a 45 minute exposure your camera needs to do another 45 minute exposure with the shutter closed to create a dark noise exposure to subtract from the first exposure to remove noise due to the heat generated by the sensor while the shutter was open for the first 45 minute exposure.
\
This may explain why in your second trial there was no resulting image as you had not allowed the camera to do the second exposure to then subtract the noise.

Regards

Chris
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?

Last edited by Michael Piziak; 10-02-2021 at 09:48 PM.
10-02-2021, 09:57 PM - 1 Like   #10
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QuoteQuote:
Question: How long of an exposure can I take using this method?
With Bulb, depending on how you have your camera setup a)push to open, wait, push to close - as long as you want to wait. b) you can stack a long series of 30-second frames to get longer star trails. 3) Using an intervalometer you can set it up to take up to 24 hours 4) with a wired external shutter release, you can push to open the shutter, then lock it open until you are ready to close it.

Here is the light pollution map for West Virginia - _________________

It's all experimentation based on your location. It is also a balance between how much light is in the sky and the light domes in the surrounding areas.

That was a good capture! I see that you are starting to get some fall colors back there....


Last edited by interested_observer; 10-02-2021 at 10:08 PM.
10-02-2021, 10:07 PM   #11
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QuoteOriginally posted by interested_observer Quote
With Bulb, depending on how you have your camera setup a)push to open, wait, push to close - as long as you want to wait. b) you can stack a long series of 30-second frames to get longer star trails. 3) Using an intervalometer you can set it up to take up to 24 hours 4) with a wired external shutter release, you can push to open the shutter, then lock it open until you are ready to close it.

Here is the light pollution map for West Virginia - _________________

It's all experimentation based on your location. It is also a balance between how much light is in the sky and the light domes in the surrounding areas.

Wow, that light pollution map is really *NEAT* ! The city I live close to ~18,000 people, and I definitely live in a light pollution area of the state, even though our state is a low population state in the eastern U.S.

I believe the Pentax k-s2 I'm using has built in intervalometer features. I think the k-s2 has quite a few astro-photography features for a mid level camera. It's also weather resistant, so that's good too for leaving the camera outside a while - never know when a few sprinkles are going to come down! But the manual lens isn't WR, so that could be an issue


I am actually really pleased and a little excited at the results I have achieved tonight - even though they are far far from optimal compared to the beautiful pics that people have taken of star trails. I realize I have way too much over exposed areas between my stars/planets. Again, I'm just glad to get some results, after a handful of failures trying to get what I got (in image 1). It is quite satisfying when you figure things out in photography....

Last edited by Michael Piziak; 10-02-2021 at 10:14 PM.
10-02-2021, 10:15 PM - 1 Like   #12
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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.

10-02-2021, 11:52 PM - 2 Likes   #13
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QuoteOriginally posted by Michael Piziak Quote
Oh well, it's my first attempt. It's very cloudy also, so only the 1 planet is prevalent.
Looks like you had a earth quake while recording you first star trials images. Any injuries, I mean are you Ok?
10-03-2021, 06:36 AM - 1 Like   #14
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QuoteOriginally posted by interested_observer Quote
Get a copy of Stellarium for your PC (its a free download) to show you where everything is.
+10 ! This may be my most-used program (well, after WordPerfect, I guess)

Then get "Heavens Above" - Heavens-Above (put in your proper coordinates, unless you want to see what's happening out here!) to see when/where to add some Space Station trails to your shots.

QuoteOriginally posted by Michael Piziak Quote
I think ISO 100 would be appropriate considering the light pollution coming off the back of my house and other houses in the area...
No - you want higher, or you won't get (m)any stars - just Jupiter/Saturn . As you are aware, the way to beat light pollution is to go to a dark sky area (not turning down the ISO). I'm not sure where you are in WVa. I lived for four years in Green Bank (50 miles south of Elkins, WVa) at the National Radio Astronomy Observatory - that was DARK! The nearest McDonalds was 50 miles away!

QuoteOriginally posted by seventhdr Quote
This may explain why in your second trial there was no resulting image as you had not allowed the camera to do the second exposure to then subtract the noise.
And, TURN OFF noise reduction! Otherwise, you will spend half your life waiting on the camera. This is totally unnecessary for all but the most fussy shots. Especially while learning how to do things.

---------- Post added 10-03-21 at 06:39 AM ----------

QuoteOriginally posted by Michael Piziak Quote
Not optimal, as in the future I want a lot of black in the image.
A bit of post-processing (adjusting the dark level) should help turn a lot of that sky background to black(er).
10-03-2021, 06:48 AM - 1 Like   #15
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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.
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