Astrophotography Workshop by Mike Dryland

Flamsteed Astronomy Society

“Getting started in Astrophotography” workshop with Tony Sizer  — April 20, 2009

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DSLRs (Digital single-lens reflex cameras)

DSLRs are very versatile for astrophotography, and of course, can also be used for demanding ‘normal’ photography.  DSLRs have interchangeable lenses and can be fitted with an adapter in place of the lens, to attach the camera to a standard telescope eyepiece holder.  The camera can be controlled by a cable-release to trigger the shutter without jolting the camera or telescope.  Indeed, modern DSLRs can be fully controlled from a laptop via a USB connection.

DSLRs are best suited to imaging the Moon and planets but are not ideal for deep-sky subjects (nebulae).  Most DSLRs have a built-in infra-red filter which will cut-out the H-alpha wavelength wanted in nebula imaging.  It is possible to remove the built-in filter but this is not recommended for beginners because removal will invalidate the camera’s warranty, may disturb the dust removal mechanism, and make the camera less than useful for ‘normal’ photography.  Webcams and CCD imagers are better suited for photographing nebulae.

Using a DSLR attached to a telescope also really requires the camera to have a ‘live view’ feature where the camera’s view can be displayed on the LCD screen before taking a picture.  Not all DSLRs have this facility.  Without it, trying to frame the image through the viewfinder of the camera can be quite difficult.

Attaching a DSLR to the telescope also places demands on the telescope mount.  A DSLR adds significant weight at the eyepiece-end and needs to be balanced.  An equatorial mount with smooth motor drives, or a smoothly tracking goto mount, will be required for subjects needing longer exposures.  A motor focus will be an advantage for more advanced work.

Webcams

Webcams originally intended for connection to the internet via a PC or laptop, have opened up a whole new set of opportunities for astro-photographers.  A webcam like the Philips TouCam (now the SPC 900 or 920C) costs under £100.  The webcam requires to be modified for use in astro-photography.  The webcam lens and built-in filter need to be removed, and an adapter fitted to attach to the scope eyepiece holder.  A UV filter on the webcam will also help exclude dust from the webcam chip.  Some dealers may supply such modified webcams.

A webcam requires connection to a laptop or PC to control it and also to collect and store images ready for further processing.

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Occultation of Venus by Malcolm Porter

Occultation of Venus by the Moon 18 June 2007

Williams refractor w/Nikon 885 camera

by Malcolm Porter

Susan and Veronica examine a Canon DSLR camera   [pic Mike Dryland]

Tony Sizer by Mike DrylandThe Moon by Tony Sizer

The Moon — Mare Crisium, Feb 2005

ROG 28-in, Canon DSLR by Tony Sizer

[Pic Mike Dryland]