Astrophotography Hints and Tips

 

If you have any questions about setting up or imaging, please feel free to e-mail us and we will do our best to help. All of our images are on the new EAAS Gallery.

Clear Skies

 

Mark & Nigel Stronge

Feel free to contact us via the EAAS Forum where we will be glad to help you get started in astrophotography.


Telescope requirements

  • Steady mount
  • GOTO or motorised scope preferred for ease of tracking
  • Appropriate magnification for viewing conditions
  • Good collimation, especially SCTs and Newtonians

Recommendations for successful imagery

  • Test your system during the day before use.
  • Collimate - try it using a webcam and laptop, laser collimator or Cheshire eyepiece.
  • Check your focus distance with and without a barlow or diagonal as refractors and newtonians may require an extension tube for a webcam to achieve focus. It may be easier to do this during the day as long as you can focus at a very distant landmark.
  • When using a barlow or eyepiece projection, do not over magnify image. 2 times oversampling (2 pixels per theoretical resolution of scope) is recommended for best sharpness - a small sharp image is better than a big blurry one.
  • Use appropriate magnification for the conditions.
  • Remember to charge your batteries and bring spares.
  • When imaging the Sun, use a towel or thick covering to shield the Sun from laptop screen.
  • Test your mount for backlash, mirror slop, mirror shift, and periodic error (K3CCDTools is great for this).
  • Vibration isolation feet make a big difference to observing and imaging.
  • Allow SCTs and Newts to cool down outside for at least an hour before imaging.
  • For long exposures, accurate polar alignment using drift or refined alignment (GOTO feature)
  • SCTs polar alignment instructions using Clay's Kochab clock
  • German Equatorial Mounts (GEM) polar alignment instructions by Ron Wodaski
  • Polar Finder software helps give you the correct offset from Polaris to the North Celestial Pole.
  • Focus mask - try focusing on a bright star and then slewing to your subject. Either use a Hartmann mask or similar. We use 2 equilateral triangles at 90 degrees to each other instead of circles.
  • If your scope wobbles on it's mount, try unbalancing it very slightly so that constant pressure is exerted in one axis. If you are using a digital camera, you probably wouldn't need to do this.
  • Try moving your scope on it's mount and check for any looseness in the tripod or worm gears, tighten accordingly.

Recommended Online Resources

Calculating your Field of View

  • Ron Wodaski's Magic CCD calculator for Webcams, Digital SLRs and CCD astro cameras
  • Ron Wodaski's New CCD Astronomy book is a must have for serious astrophotographers. Expensive but worth it.
  • The Philips TouCam Pro uses the Sony ICX098BQ CCD chip - 659x494pixels 5.6x5.6um
  • Canon Digital SLRs use 6.3-megapixel, 7.4 by 7.4µm pixel size, 22.7mm x 15.1mm CMOS chip
  • Fixed Lens Digital Cameras - you will need the resolution of your camera, CCD chip diagonal size and zoom range in digital format (not 35mm equivalent).
  • K3CCDTools has a FOV calculator in the software in which you can enter your scope details and imaging chip size.
  • Critical Focus Zone = (focal ratio)2 x 2.2 (one thousandth of a millimetre is one micron)

Camera adapters

Scopetronix Maxview 40mm or Maxview2 2inch eyepiece and T-adapters great for using automatic digital cameras with a telescope.
Small barrel lens adapters available from North Down telescopes.
TouCam Pro UWAT-F webcam adapters available from Steven Mogg, US$24 delivered or North Down Telescopes.
 

Online Discussion Groups

More information about using digital cameras for astrophotography is available at the Digital Camera Astro website and their associated Yahoo discussion group.

The Canon Digital SLRs all have remote use functionality. Check out the dslrfocus website and it's associated Yahoo discussion group.

More information about using web cameras is available at http://www.qcuiag.co.uk with the associated Yahoo discussion group.

Webcam Modifications

For modifying webcams visit Steve Chambers's website or you can purchase already modified webcams at Perseu.

USB Webcams

The following webcams are the best option for budget CCDs.

  • Philips SPC900NC
  • Philips Toucam Pro 840K (discontinued)
  • Philips Toucam Pro 740K (discontinued)

The SPC900NC, 840K and 740K are identical. Do not be fooled by the greater frame rate as this is still a USB1.1 webcam and frames are limited by USB bandwidth to 5fps 640x480 uncompressedMmmm Silver, still the same inside though.

  • If you wanting to buy a webcam, look for the use of a CCD chip and at least 1Lux sensitivity or better. Better is 0.1 Lux.
  • Click here for specifications of a wide range of webcams
  • Buy the Philips 900NC from Amazon.co.uk
  • Buy the Philips SPC900 from Pixmania.co.uk
  • Scopetronix adapters

 

Firewire Webcams

  1. Orange Micro i-Bot Firewire and USB 2.0 version

Long Exposure Modifications

Digital Cameras

  • Look for digital cameras that have a "B" setting or exposure times of at least 30 seconds. For the ultimate, have a look at the digital SLR cameras which are a perfect replacement for the old manual SLRs.
  • For digital camera reviews, check out the Imaging Resource website where direct comparisons can be made. Look for a camera that does long exposures of around 30 seconds or more. The Nikon Coolpix are very good and some do up to 300 second exposures. For the best price on digital cameras, buy from the USA. For a digital SLR, look at the Canon EOS300D Digital Rebel - a digital SLR for around £600 from the USA.
  • Remote shutter release is a must to achieve sharp, unblurred images with a digital camera

Digital SLR Astrophotography

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  • Buy the Canon Digital Rebel 350D digital SLR BODY ONLY
  • Buy the Canon Digital Rebel 350D digital SLR with lens

Software

  • Starry Night Pro is probably the best planetarium program available. It is extremely realistic looking and is the next best thing to actually going outside! Deep Sky Objects are viewable as a photographed image overlaid automatically on the star chart. The program features an automatic star download so that when you are connected to the internet it will download more stars as you zoom in on a certain area up to Mag22 !!! Very useful for astrophotography and easy to use. The program also gives many details about each constellation/star/nebula/galaxy etc .which will keep you enthralled for hours. Starry Night Pro can control a telescope and now has fine controls for centring and focusing.
  • Cartes Du Ceil is an excellent free sky chart software that can show detailed star charts down to Mag18 with the downloadable HST star catalogue. Also available is downloadable comet and asteroid paths and even very accurate ISS and iridium flare predictions with the predicted path overlaid. Cartes Du Ceil has a dedicated Yahoo forum where you can post comments, suggestions and questions to the experts who know the program inside out. Cartes Du Ceil can also control computerised telescopes and can remotely focus and track celestial objects. This is the one I use when remotely controlling the telescope.
  • Virtual Moon Atlas is another free program that shows the Moon in 3D with all of the craters named including the far side of the moon.
  • K3CCDTools video capturing and processing software with autoguiding and support for long exposure modified webcams.
  • Keith's Image Stacker is like Registax, only for an Apple Mac.
  • Registax for aligning and stacking astro-images. This is the best software for stacking and processing your astro-images and is completely free. Registax has 2 downloadable tutorials available from the software website. Please note that there are 2 versions depending on your desktop resolution.
  • Paint Shop Pro for Final Processing. You can use Photoshop or any other graphics software but we find Paint Shop Pro excellent value for money with some nice unique features (like the automatic colour balance).
  • For creating mosaics use iMerge It is another free bit of software but is incredibly powerful, K.I.S.S. to use and recommended by many astrophotographers.
  • Ultr@VNC is great software for connecting to your webcam and computer controlled telescope either over a network, wireless network or internet (with broadband).

Accessories

  • Sky Atlas 2000 Deluxe Laminated and Spiral-Bound - the utimate laminated star chart to Mag8.5 for both hemispheres.
  • Firefly Planisphere Deluxe - the ultimate planisphere with stars to Mag6 shown with colour spectra, greek listing for brightness, binaries and doubles; as well as all the Messier objects and many NGC objects. For more advanced observers. My personal favourite.
  • Philips Planisphere - Stars to Mag 4 with some deep sky objects shown. This is the standard by which others are set.

Remotely Controlling your telescope for imaging

If you have an observatory, it is possible to fully automate your observatory with regard to a weather station, dome control, telescope and focus control, and even remote image capturing. The simpler way is to using extension leads going into your house, but you can also have an Observatory computer controlled either over the internet or via a wireless network using secure, encrypted software. Look above for the Ultr@VNC software. You could also try using the Windows XP Remote desktop feature.

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Get at least two USB 5 metre extension cables

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You will probably need two serial 5 metre extension cables

 

 

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Last Updated : Thursday, December 21, 2006

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