Username:

Password:

Altair AstroDIO DehumidifiersAtik CamerasModern AstronomyDavid HindsNe3 Filters

Author Topic: Making star trail images with a DSLR and Startrails v1.1  (Read 4607 times)

0 Members and 1 Guest are viewing this topic.

Offline Dangerous_Dave

  • Poster God
  • *****
  • Posts: 2373
  • Deep sky acolyte
    • Dave's pics
Making star trail images with a DSLR and Startrails v1.1
« on: 13:18:11, 02 October, 2008 »
Hi folks, I wrote this tutorial for another forum I contribute to and thought one or two people on here might find it useful.

Quote
Equipment

1. A good solid tripod (inc tripod head)

I use a Manfrotto 055XB and 804RC2 three way head but honestly anything will do, providing there is no risk of slippage or wind vibration. Some tripod heads, like my 804RC2, only tilt upwards to c.45 degrees, but you should be able to use them reversed.

2. A DSLR with continuous shooting mode and takes a shutter release cable

On Canons, continuous shooting mode is the icon with the little stack of frames

3. Lockable shutter release cable

I use a Canon TC80N3 remote interval timer which operates as a lockable shutter release

4. Wide angle or fish eye lens

The shorter the focal length the better, because we want to get in as many stars as possible. You can take star trails with any lens, but over 25mm or so you will start to struggle to include any foreground and the trails could appear as uninspring straight lines.

I use a Sigma 18-200 zoom lens set to 18mm.


5. Power supply and camera power cable

In a star trail sesh, we need to take several hours of uninterrupted subs, so the last thing we want to be doing is changing batteries.

You could use a mains adaptor plugged into extension lead or, as I do, a 12v jump starter with an Astronomiser power adaptor for my particular camera. A fully charged jump starter will last all night taking star trails.

6. Some form of dew control

A lens hood will afford some form of dew prevention, but if you intend to capture over an hour or more and/or you are imaging in an area prone to dewing (ahem Kielder) and/or it's a fairly damp night it would be wise to employ some other form of dew control. You could use a dew strap and controller, though personally I can't be bothered with the extra cables so I will either chance it, or warm the lens with a hairdryer at regular intervals (unfortunately you will not be able to shine a torch at the lens during the run to check how dewy it is!).

7. Startrails software

Download Achim Schaller's superb Startrails software - freeware.

My setup:



Capturing the images


1. Camera settings

(It goes without saying we are using the DSLR in MANUAL mode!)

1.1 Memory card

The first thing you will need to do is wipe your camera's memory card - format it, don't just delete the pics. We want to capture as many shots as possible so need as much free space as possible. If you have several memory cards, it goes without saying - use your biggest one.

1.2 Resolution/compression settings

Startrails can't handle RAWs, and they're big and waste card space, so we are going to shoot in jpeg format. The quality setting we select will depend on the resolution of your camera, the size of your memory card and the length of the imaging run but we want to aim to use the largest and least compressed we can get away with. I generally go for Medium/uncompressed setting on the 300D - I can get 500+ subs on my 1GB flash card at this setting, and could afford to go up to large, but a lot of the time I am using my smaller, 512MB flash cards so like to keep things consistent.

1.3 Mirror lockup

Turn this off

1.4 Shooting mode

Set the camera to continuous shooting mode - the icon for this on the Canon is a little stack of frames, there is a button which cycles between continuous shooting mode, single shot mode and timer shot. For Nikon, Pentax etc consult your manual.

1.5 Exposure/Aperture/ISO

We are going to take 30 second subs. The main reason for this is 30 seconds is the longest non-bulb exposure setting we can take with the Canon. I suspect this is fairly ubiquitous!

As for aperture, we are going to aim for the fastest we can get away with. That's f3.5 on my Sigma lens at 18mm. If you have a lens which degrades at faster apertures you may need to stop down a step or two.

Again for ISO setting, we want this as high as we can get away with, though we have to bear in mind the noise profile of the camera at different ISO's and reduced dynamic range of the shot for post-processing. Personally, I find ISO400 a very nice compromise between dynamic range, noise and sensitivity for the 300D, but if I was using my 20D (which doesn't seem to get on with the Astronomiser power cable, sadly) I'd venture up to 800 or perhaps even 1600.

2. Preparing the shot

2.1 Framing the shot

OK, this is pretty obvious but we need to pay some attention to what we're going to have in our shot. Ideally we want some sort of interesting foreground to complement the stars and to pick an area of sky where there will be a range of stars of different magnitudes and colours, and we won't be bothered too much by air traffic - OK, realistically imaging large areas of sky over a few hours in this day and age you are almost guaranteed a plane trail, but you can increase your chances of getting plane-free chunks of subs by imaging after midnight and pointing your lens well away from local air corridoors (like the one NW from me!).

My personal opinion is planes are bad but anything outside the atmosphere is a bonus! One idea is to frame your star trail shot on a part of sky where you know there will be an ISS pass or Iridium flare.

If you include foreground, you will need to make sure it's level - duh, pretty obvious, but harder than you might think in the dark. I generally to spend some time tweaking my tripod head, taking 30 second test images, before I'm happy with the shot. Bear in mind, if we are using a low aperture setting, the depth of field will be pretty shallow, so if your foreground object is too close it will be out of focus, eg the telescope/mount in this shot.

2.2 Focus

Even though we're just taking startrails, we want this as accurate as possible, so we capture nice sharp trails, not great big fuzzy sausages.

I found the best method here was to take a range of shots while tweaking the focus and reviewing the stars on the LCD each time, till the stars were as small as possible, and then made a mental note of the setting. If you don't have a lens with focus markings then it might be an idea to mark the point with pencil/paint etc.

Although your camera lens may have an infinity marker, don't assume stars will be in focus when infinity is dialed in! My experience is the contrary!

2.3 Start the imaging run

OK, now we're ready to go. Press the shutter release down and lock it. The camera will take a sequence of 30 second exposures until it runs out of card space, the battery runs flat or we unlock the shutter release. Depending on how quick the camera's onboard processor is,  we might get a slight delay between one shot finishing and the next one starting, but this is fairly unavoidable and not a big problem in the final image.

The length of the imaging run is entirely up to you - but I would recommend no less than one hour, and the longer the better, so it would be wise to find something else in the meantime (eg sleep, observe, watch telly!) and bear in mind, if you walk in front of the camera you will end up in the stack!  :mrgreen:

2.4 Dark frames

Like all good astro stacking programs, "Startrails" lets us subtract dark frames to remove hot pixels, thermal noise etc so before we pack up, we take a few 30 second shots with the lens cap on.

Processing the shots[/u]

1. Upload the subs

Again - goes without saying, we need the jpegs on our computer for processing. You might find, with that number of images, the camera arranges them into several different folders on the flash card, however we need them all in the same folder on our hard-disk. It is worth double checking your subs to make sure they have all copied across - one way to do this is to order them by name (assuming your camera auto-names subs alphanumerically) or order them by time taken and look for any obvious gaps.

2. Stack the subs in Startrails v1.1

This piece of software really couldn't be any easier to use and there are thorough  instructions on Achim Schaller's website, but all the same here is the process:

2.1 Open the subs

Select File/Open Images, or the leftmost icon on the toolbar.

2.2 Open your dark frames

File/Open Dark Frames, or icon second from left on toolbar

2.3 Average foreground

This allows us to create an averaged foreground image which is blended back into the final shot. Select Build/Average Foreground or the big Sigma (greek letter) on the toolbar then select the number of frames to average (I generally use about 10)

2.4 Build startrails

At this point we might want to uncheck any frames that include aeroplanes, helicopters etc from the list box on the left!

Select Build/Startrails or the button on the toolbar second from right and watch the fun!  :cwm21:



If you're satisfied with the result, save it (as a lossless TIFF for further processing) - if not, you might want to go back and remove any problem frames.

The final shot:



At this point we could also produce a video (Build/Video or rightmost icon on toolbar) which is great fun to watch, though I confess to being a bit bamboozled by the compression options so haven't managed to produce one small enough to post on here - if anyone can figure that out, please let me know!

That's it! Not difficult at all, and I've probably waffled on far more than I needed to, but I hope it encourages you to have a go. If I've missed anything - which is entirely possible - please shout up.


D
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline beekeg

  • Galactic Poster
  • ******
  • Posts: 3686
  • The Sun is a mass of incandescent gas
    • Cosmicshed
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #1 on: 16:02:46, 08 October, 2008 »
Nice tutorial Dave.  Have some K
Borg 60ED, TMB 105, TMB 152, QHY5, YR Trifid 6303E, FLI CFW2/7, Aim Controls EQ1 Mount and loads of stuff to connect them all together.

Offline swashy

  • UKAI GFX Guru
  • Administrator
  • Galactic Poster
  • *****
  • Posts: 14659
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #2 on: 17:36:45, 08 October, 2008 »
Great tutorial Dave, I'll be giving this a try soon

Quote
1.1 Memory card

The first thing you will need to do is wipe your camera's memory card - format it, don't just delete the pics.

what is the reason for the format, is this something I should do on a regular basis? I normally just delete the stuff after a session
Ade

Imagine...  above us only sky!

Offline Dangerous_Dave

  • Poster God
  • *****
  • Posts: 2373
  • Deep sky acolyte
    • Dave's pics
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #3 on: 11:47:41, 09 October, 2008 »
Great tutorial Dave, I'll be giving this a try soon

Quote
1.1 Memory card

The first thing you will need to do is wipe your camera's memory card - format it, don't just delete the pics.

what is the reason for the format, is this something I should do on a regular basis? I normally just delete the stuff after a session

Ade, I don't know the science behind it but my personal experience has been that simply deleting the pics has led to two compact flash cards becoming corrupted after a few sessions, especially where large numbers of files were concerned. On one CF card, I deleted a single sub and it wiped out about three quarters of the files on there. I presume there is some sort of hidden index or swap files that can become corrupted.

Since then, I have reformatted after every session and not had any problems...
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline egdavies

  • Galactic Poster
  • ******
  • Posts: 7399
  • Necessity is the mother of all inventions
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #4 on: 15:06:56, 12 October, 2008 »
Only just seen this along with your other star trail shots, stunning stuff!

Have some K from me too!

Eddie
MK1 Eyeball

Offline swashy

  • UKAI GFX Guru
  • Administrator
  • Galactic Poster
  • *****
  • Posts: 14659
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #5 on: 11:05:37, 22 October, 2008 »
I seem to be getting dotted stars instead of smooth lines, I can only put this down to the short pause between exposures, shooting on full res jpeg, next time I will try a lower res and see if it saves the image quicker perhaps?

[attachment deleted by admin]
Ade

Imagine...  above us only sky!

Offline Dangerous_Dave

  • Poster God
  • *****
  • Posts: 2373
  • Deep sky acolyte
    • Dave's pics
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #6 on: 23:03:07, 26 October, 2008 »
I seem to be getting dotted stars instead of smooth lines, I can only put this down to the short pause between exposures, shooting on full res jpeg, next time I will try a lower res and see if it saves the image quicker perhaps?

Hi Ade, some gaps are inevitable using this method but you can minimise them by reducing jpeg res and using as short a lens as you've got. I experienced a pause of 3-5 seconds on large jpeg (300D) but this was 1-2 seconds at medium.

Another cause of this effect can be using a lens with image stabilisation - a lad on another forum experience this problem.
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline Stuart

  • Poster God
  • *****
  • Posts: 1266
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #7 on: 10:30:15, 27 October, 2008 »
Aha, I thought by having a large CF card and selecting L jpg I was doing a good thing, but I too go a very annoying series of dots; you live and learn. 

Offline swashy

  • UKAI GFX Guru
  • Administrator
  • Galactic Poster
  • *****
  • Posts: 14659
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #8 on: 12:28:18, 27 October, 2008 »
Yup, it seems less is more in this instance
Ade

Imagine...  above us only sky!

Offline boothee

  • Senior Member
  • ****
  • Posts: 679
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #9 on: 15:06:03, 27 October, 2008 »
Aha, I thought by having a large CF card and selecting L jpg I was doing a good thing, but I too go a very annoying series of dots; you live and learn. 

Oh!  I haven't tried star trails picture using my Canon EOS 300D which use CF card.  When I go and buy my CF card, sell advice me to buy a faster speed card which is 10 times more expensive than normal one.  I just choose normal speed.  Seems like I will also have that soft of dots when I capture with Large or Raw format.  :(

Can't try yet as there is a storm in Bay of Bangal.  :(

Clear Skies!

boothee
1150mm, 254mm, Newtonion Reflector on EQ5 Mount with dual axis DK3 drive, QHY5 Planetary Imager, Canon 300D, Yangon(Rangoon), Myanmar(Burma).

Offline Nomis Elfactem

  • Administrator
  • Galactic Poster
  • *****
  • Posts: 13004
    • The View From A Room
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #10 on: 15:56:21, 27 October, 2008 »
When I took my star-trail images I had the camera plugged straight into my laptop and the images were loaded as soon as they were taken so it didn't have to wait for the card to come back online after taking a shot... I also don't have "fast" CF cards but don't seem to have any problems with them ?!?

Remember if you are connecting direct to PC/Laptop to make sure the "take image without CF" is set to yes !

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline Stuart

  • Poster God
  • *****
  • Posts: 1266
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #11 on: 17:06:35, 27 October, 2008 »
I would have thought that the buffer would take care of 1 picture every 30 seconds regardless of how fast your CF card is so you should be ok with a "normal" speed one, whatever that may be these days.  I used to have shoot without CF card set to yes until I did the classic of taking loads of shots with no "film" in! I also has to set the long exposure NR off, does that kick in for 30 second exposures, not sure, probably.

Offline Stuart

  • Poster God
  • *****
  • Posts: 1266
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #12 on: 01:10:59, 28 October, 2008 »
Couldn't get a decent foreground but the trails are looking better.



[attachment deleted by admin]

Offline tooth_dr

  • Poster God
  • *****
  • Posts: 929
    • The Beauty Retreat
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #13 on: 09:23:38, 28 October, 2008 »
Great tutorial Dave

Looking forward to go at this myself the next clear day :)


Adam
EQ6 Pro Synscan : SW 250px : ED80-Pro2 : ST-80 : Celestron 60mm : EQ1 TT : Bresser 10x50 : EOS400d : Baader-modified EOS300d  : SC1.5 monochrome Toucam : Self-modified SC1 Toucam : Roll-off Roof Observatory : All necessary leads and software

Offline Dangerous_Dave

  • Poster God
  • *****
  • Posts: 2373
  • Deep sky acolyte
    • Dave's pics
Re: Making star trail images with a DSLR and Startrails v1.1
« Reply #14 on: 20:33:03, 04 November, 2008 »
Couldn't get a decent foreground but the trails are looking better.



That looks pretty good to me Stuart!
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

 

ukbuysellRemote Imaging from AustraliaSharpSkyblank APTUKAI on Facebook
Powered by SMF 2.0.15 | SMF © 2006, Simple Machines LLC
DarkBreak by DzinerStudio. Theme modified by The UKAI Team

Page created in 0.379 seconds with 37 queries.
TinyPortal © 2005-2012