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FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial 
Thread started 11 Mar 2013 (Monday) 23:28
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Startrails - A Successful Failure

 
doidinho
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Mar 11, 2013 23:28 |  #1

This is the result of my first attempt photographing star trails. I thought it would be nice to do a brief write up up about how I prepared, how the shoot went, what went right, what went wrong, and what I will plan to do differently next time.

My hope is that I can get some good suggestions to put to use on my next shoot and that others who are gearing up for their fist attempt may be able to glean something from my write up (and the responses that hopefully follow).

I had been reading up on how to photograph the night sky for about a month. I picked up an ephemeris app, started monitoring the weather, learned about clear sky charts, and read all I could find on how to best capture star trails.

For the location I settled on a small ledge I knew which is about an hour from my house. I chose the location pretty much just on it being relatively far from the city and because I had been their before and knew my way around (helpful for finding your way in the dark). The plan was to get to the park, hike a couple of miles to the ledge, start shooting around 2am, and shoot into twilight (around 5:30am) to get some light on the foreground which I knew would be dark as it was just two days before the new moon.

The forecast was finally looking decent for the evening of Friday, March 9th. I felt that had learned as much as I could from the internet and I had a plan; it was time to shoot. I left my house around 11pm, got to the location at midnight, gathered my gear together and headed out to the trail head around 12:30am. Right before I got to the trail head I decided it was time to locate the north star to ponder composition on my way up to the ledge. After locating the north star I started to think that perhaps a view of the ledge from below would make a better image. I then realized that this was my first time photographing star trails and therefore I would likely make some mistakes. Suddenly, a shot from the lower (and much closer) location became much more appealing:)

I decided to take the lower shot and headed out to the other end of the lake which is below the ledge. I thought I could get a nice composition from there and would also be able to get some star trail reflections. After arriving at the general shoot location around 1am I began to shoot some test shots at ISO6400 and wide open in order to find a good spot to shoot from. After finding my spot and figuring out my exposure base on the appearance of the test images on the back of the camera, it was time to focus. I settled on f/4.5, and a 2 minute exposure time at ISO 400.

The aperture was set based on me reading that wider was better and that wider makes stars brighter. I didn't know if this was what I really wanted, but knew I needed to start somewhere and thought this would be my best guess. Exposure time was set based on me wanting to keep it at or below two minutes. In the past I had noticed a real increase in noise when exposures go above two minutes for other types of shots, so I thought two minutes would be a good starting point. ISO came out to be 400 which was fine. I took a dark frame at my chosen settings and at 1:45am it was finally time to shoot.

I set up my Magic Lantern bulb exposure and intervalometer and the camera started clicking away. Everything was going smoothly and the exposures looked good in the LCD. At about 3:00am I noticed that the images were coming out foggy and discovered condensation on the lens. There was a lot of condensation on the lens and I also noticed that condensation on the tripod was starting to freeze. I decided that it was time to end my session, so I took my camera off the tripod, dried and cleaned the lens, took a +2EV light exposure, took two final dark frames and headed home. I was kinda bummed, but halfway expect battle the learning curve to some extent on my first shoot.

After transferring the files to Lightroom I noticed that the images actually got foggy around 44 minutes rather than 1.25 hours when I noticed it in the viewfinder. Oh well, at least I had a few images and could work through the assembly process. As it also turns out, the the images were all underexposed by about one and a half stops. I'm attributing this to the fact that I didn't turn my viewfinder brightness down, it was too high, and that it resulted in me overestimating the exposure. It also turned out that I must have bumped the tripod and changed the focal length while cleaning my lens off tripod. I could not get the final light image I took for the foreground to align with the rest of the images.

Here is the result of my 44 minute exposure without the foreground lighter foreground frame. Lesson learned, don't rely on iphone apps to locate the north star; learn to locate it yourself. I intended the north star (and the center of the spinning) to be about 1/3 down into the frame and a little bit to the right:)

IMAGE: http://farm9.staticflickr.com/8513/8547821707_bfaff04622_b.jpg
IMAGE LINK: http://www.flickr.com …/27883438@N07/8​547821707/  (external link)
Startrails1 (external link) by Doidinho (external link), on Flickr

And now for the questions.

What do you do for dew?

I searched around and it appears that a dew heater (made for a telescope) may be the ticket. I called up the closest store that stocks them (a couple hours drive by car) and they were super helpful, but didn't have any actual experience using them with camera lenses. They suggested I try a Kendrick heater (external link) with an Astrozap controller (external link). Does this sound right? Anyone have any first hand experience using these?

What do you do if dew does form? Is there a way to successfully fight it while shooting?

How do you monitor it? I don't think I could see it without shining a light in the lens and ruining a frame.

How do you expose and compose when shooting into the night?

f/4.5, 120s, ISO 400 was at least 1.5 stops over this time, so next time should I just set it to f/4, 120s, ISO 800 and start shooting around twilight? Are there or do you have any rules of thumb for seting exposure when shooting into the night?

What if I start out too soon and end up underexposing? Do I just adjust everything manually until I zero in on the perfect settings and then take a little bit longer break, set the intervalometer and bulb timer, and then resume shooting?

How do you locate the north star prior to the star being visible in the sky?

Thats about it for me tonight. Any comments, critique, advice, or additional questions would be appreciated.

Robert McCadden
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evan55
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Mar 12, 2013 01:05 |  #2

Turned out pretty decent, looks like there is a airplane light trail by the mountains.

Which program did you use to compile this?


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Omri ­ Alon
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Mar 12, 2013 03:25 |  #3

Nice shot! I also tried my first startrails just a day after you did. I got to my location at sunset, so setting up was easier.


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etaV8R
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Mar 12, 2013 06:07 |  #4

Looks like a great start. I'm trying to learn about this as well so I really can't offer any help with the issues but am anxious to hear suggestions of others.


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Joe929
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Mar 12, 2013 08:23 |  #5

It looks very good to me, what was your focal length?


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doidinho
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Mar 12, 2013 08:52 |  #6

evan55 wrote in post #15705185 (external link)
Turned out pretty decent, looks like there is a airplane light trail by the mountains.

Which program did you use to compile this?

I compiled the pictures in photoshop. I didn't do any retouching this time since I plan on reshooting and just wanted to figure out the compiling process.

Omri Alon wrote in post #15705386 (external link)
Nice shot! I also tried my first startrails just a day after you did. I got to my location at sunset, so setting up was easier.

One of my questions was about how to determine exposure when you set up before the stars come out. Do you have any tips? Feel free to share the image too:)

etaV8R wrote in post #15705591 (external link)
Looks like a great start. I'm trying to learn about this as well so I really can't offer any help with the issues but am anxious to hear suggestions of others.

Great, if you have any specific questions, post em up and we can try and work through them here.

Joe929 wrote in post #15705920 (external link)
It looks very good to me, what was your focal length?

Thanks Joe, an important piece of omitted info. I shot with my 24-105 at 24mm.


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Omri ­ Alon
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Mar 12, 2013 10:47 |  #7

doidinho wrote in post #15706006 (external link)
One of my questions was about how to determine exposure when you set up before the stars come out. Do you have any tips? Feel free to share the image too:)

From what I understand, at 24mm you have about 20secs until the stars are in a different place in the frame. So, as long as your shutter speed is slower than 20 seconds, the factors that determine the brightness of the stars are ISO and aperture.
What I tried to do is expose the BG correctly.
I shot mine at f/4 and ISO 1600.

This is my image:
https://photography-on-the.net …/showthread.php​?t=1282632


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doidinho
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Mar 12, 2013 18:20 |  #8

Omri Alon wrote in post #15706434 (external link)
From what I understand, at 24mm you have about 20secs until the stars are in a different place in the frame. So, as long as your shutter speed is slower than 20 seconds, the factors that determine the brightness of the stars are ISO and aperture.
What I tried to do is expose the BG correctly.
I shot mine at f/4 and ISO 1600.

This is my image:
https://photography-on-the.net …/showthread.php​?t=1282632

Thanks for sharing. I'm on board with your understanding of the exposure. What I do not understand is how I can determine the correct exposure prior to it being dark.

When I set up it was already dark. I simply shot some test images at my highest ISO and then calculated my actual exposure based on my test shots.

When you set up how did you know that the exposure you started with would be the correct exposure later on when it got dark? Did you ramp the exposure up as it got darker?


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SteveInNZ
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Mar 12, 2013 19:32 |  #9

Firstly, I really like your failure. I'd be very happy with that.
I have dew straps and use them for camera lenses. You don't need to use them with a controller, it's just more efficient to do so and you'll get better battery life. Choose a strap based on the circumference of your lens. I also use disposable handwarmers which work very well. They're hopeless for warming your hands but you only need a couple of degrees above ambient for the lens and they last all night.
To clear dew off a lens once it's formed, I use a 12V hairdrier. I dry something off the camera as well and then test that by wiping my finger on it. If it's damp, i dry it and the lens. The drier is black so it doesn't show up in the photo. That's a last resort though.You really don't want to get dew on your lens.

If you can't see your lens without a light, get a red light and read up on dark adaption. Once you are dark adapted, starlight is plenty of light for most things. It only takes seconds to ruin an hours worth of dark adaption.

It looks like you have a nice dark site so the limitation on exposure time is just the background noise that you find acceptable. You can test that by shooting dark frames with the lens cap on. You'll want them later anyway. Then you can adjust the ISO and aperture to determine how many stars you want. Wider aperture and higher ISO give you more trails. Yes, you can have too many but that's a matter of taste and you'll have to experiment yourself.

I'm not sure if the bulb ramping is an advantage here or not. I know how it works but haven't used it. I usually start in the evening, set for my exposure time and throw out the overexposed ones until the light drops to the right level. Twilight also tends to be very flat lighting. A little bit of moonlight gives you much more texture. Your failure would look great with a bit of low angle moonlight.

A compass or compass app is really good for finding north. If you know where you are going, Google Earth is also really helpful. Use the ruler tool to find a landmark due north of where you'll be. Also look up your latitude. The angle from the horizon to the pole star is the same as your latitude. It can be handy to find what the angular view of your lens/camera combo is beforehand. Then you know if you can get the pole star into your shot as well as the foreground.
Eg. Washingtons latitude is 45N so the pole is 45 degrees above the horizon. A 17mm lens on a crop body has a view of 47 x 66 degrees so in landscape it would just scrape in and it would be fine in portrait.

Hope that helps.

Steve.


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Mar 12, 2013 19:36 |  #10

Looks real nice. Try bracketing shots. Then just go with what looks best depending on your conditions......


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doidinho
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Mar 13, 2013 14:05 |  #11

Oh boy, lots of good information:) Thanks for you replies Steve and Dave.

Steve, I think I will pick up some handwarmers and do some testing on my deck and then consider the dew heater depending on how the warmers work.

Will make sure and read up on dark adaption too. I was going to experiment with shotting in live view next time, I wonder if the preview image on the LCD will be bright enough to affect my dark adaption?

Edit, Just saw this. Even though I don't doubt it works it still made me chcuckle a bit:

" Each eye reacts separately to light, so you can keep one eye dark adapted while using your other eye to read star charts and slew your telescope. An eye patch is ideal."


Robert McCadden
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Mar 13, 2013 16:08 as a reply to  @ doidinho's post |  #12

I already had a small Mag flashlight. Bought an adapter kit that includes a red colored lens on Amazon. It works great keeping my eyes acclimated to the night yet bright enough to see switches on lenses and camera, and flashlight is fairly light to carry in bag.

MAGLITE AM2A016 Mini AA Flashlight Accessory Pack.
$4.38

http://www.amazon.com …ohs_product?ie=​UTF8&psc=1 (external link)




  
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SteveInNZ
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Mar 13, 2013 18:47 |  #13

Yes, Live-view is bright enough to spoil it. A red headlamp is ideal but with a wide lens, it's easy to have red light stray into your picture. Use live-view for setup and initial shots and then turn off anything that uses the LCD once you've started.
Lesson from last night - Don't forget to plug the dewstrap in. D'oh !
The eyepatch thing is true. I have one eye that is dominant so I find it hard to do. Some people use them at total eclipses to get the best view in totality. Useless factoid - Using the eyepatch to keep one eye dark adapted is the origin of the stereotype pirate having an eyepatch.


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Mar 14, 2013 03:14 as a reply to  @ SteveInNZ's post |  #14

Locate the big dipper, follow the handle into the pot. At the last star( top of pot) Go straight up.
That is the North Star(Polaris)


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Sgt.
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Mar 14, 2013 03:17 |  #15

This should help


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Startrails - A Successful Failure
FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial 
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