The equipment I use for deep-space imaging is reasonably modest and contains a mix of new and 2nd hand equipment. The picture of the complete setup is shown below, and then I’ll describe each of the components. I’ll replace these pictures with more purpose-taken ones soon.
I use a Saxon ED80 as my imaging scope. It has a focal ratio of f/7.5 and a 600mm focal length. It is fitted with the standard single-speed crayford focuser 9×50 straight-through finderscope.
I use a generic 80mm f/5 refractor (focal length 400mm) as my guide scope. It was bought second hand, with rings, for AU$200 and serves me perfectly fitted side-by-side with the Saxon ED80.
Mount and Side-by-Side Dovetail
I use a standard SkyWatcher EQ6 as the mount to hold both refractors. After carrying a 12″ Newtonian around, there’s likely quite a bit of periodic error and there is backlash in the gears. However for shortish focal length deep-space imaging, as long as I’m auto-guiding, the EQ6 does a fine job and the stars generally come out nice and round as long as i’ve balanced the setup and properly drift align. The side-by-side dovetail is a vixen style which has just enough room to fit both refractors and their rings without getting in each others way.
I use a standard (non-modded) Canon 350D as my deep-space imaging camera. It’s used at prime focus (without the lens) with or without the Williams Optics 0.8x reducer/flattener in the Saxon ED80. The ED80 is then effectively acting as a long telephoto lens.
I use a DMK21AU04 from The Imaging Source as my guide camera. It’s a monochrome camera with 640×480 pixel resolution and is an excellent intermediate/advanced level imaging device, especially given its low cost. It can capture at up to 60 frames per second (fps) through a USB (or firewire) interface and has a 1/4″ Sony CCD with a pixel size of 5.6 microns, giving a good image scale for most applications. It’s sensitive enough to be used as a guide camera and works well with all guiding applications.
I use the Williams Optics 0.8x Type II reducer/field flattener, which changes the Saxon ED80 into a 480mm f/6 refractor – slightly faster focal ratio for astrophotography, less focal length for a wider field of view, and flattens the field to reduce the field curvature evident in the ED80.
I use an IDAS LPS P2 light-pollution filter screwed into the WO 0.8x reducer/flattener.
GPUSB Guide Adapter
Long-Exposure Serial Cable
The long-exposure serial cable takes commands from a camera control program such as Images Plus, and controls the Canon 350D while taking long-exposures.
The light box is used for taking flat-fields after an imaging run to even out vignetting and dust motes. It’s powered by my dew-controller.
With deep-space imaging, there’s always more you can buy. You can get a bigger, more solid, more accurate mount to get better guiding and tighter stars. You can get a very expensive APO telescope with flat fields and corrected lens, you can get computer controlled focusers, you can get massive cooled CCD cameras. Literally the sky is the limit and you could spend AU$40,000 without trying too hard. For me though, the first step is to get my Canon 350D modded, which means removing the filter in front of the CMOS and replacing it with a UV/IR filter which doesn’t block hydrogen-alpha light. This will allow me to capture fainter nebula on some targets.