Wednesday, 28 February 2018

Orion redux

Here is another go at M42, taken two nights later. In this case I dropped the exposure of the individual frames down to 5 seconds, which has helped reduce the over-exposure in the core of the nebula. However, I would still need to drop it a bit further. Here I took 29 sub-frames and again combined them using Nebulosity. There are still a few bits of electronic noise in the final image. It was a race against clouds again last night, or else I would have taken substantially more sub-frames.


  1. Hi Al,

    Great pics. I really want to get into this type of thing as a hobby I can enjoy with my kids. Would you mind detailing some of the equipment you use?

  2. Hi Mirabel. There are three bits of equipment used here: a telescope, a mount for the scope, and a camera (and laptop). The telescope is a relatively small William Optics 71mm refractor, which cost around 500 pounds when I bought it a few years ago. It's not made now but similar small refractors are easily found. The benefit of this scope is its wide field of view, excellent for extended objects like nebulae and the Moon, nearby galaxies, etc, but no good for planets.

    The scope is in turn mounted on a Sky Watcher GoTo equatorial mount, which cost in the same region as the scope, but which can accept a variety of other telescopes if needed. Importantly, the scope and the mount are not so bulky or heavy that they can't be moved easily, so setting up is very simple and quick - I just carry the entire unit out through a door onto patio decking. My other, larger and heavier scope, the Celestron, is better for planets and distant objects, but can't be carried without disassembly.

    The final element is some kind of digital camera to record the light, and in this case I used a CCD made by a firm called OpticStar, which again cost a few hundred pounds. It goes onto the scope where an objective eyepiece would normally fit, with only the focus needing adjustment, so it's easy to swap between visual and CCD astronomy in just a few seconds. Camera control and image acquisition is done via a USB link to a laptop - in my case a ten year old Toshiba which is pretty useless for anything else, but can still run the control software.

    1. Hey As,

      I Have a question, so I figured I'd ask an astronomer, what would you recommend accessory-wise, if I wanted to view my telescope live on my laptop, is there anything in particular that you would recommend? Great Books, by the way, Clavain and Scorpio need a standalone novel

    2. I can see you eventually building your own observatory. Now that's a toy I'd practically live in.

  3. Hi David - I would like a dome as it would mean I could leave the telescopes permanently aligned (at the moment I have to do a polar alignment each time I set them up, which takes time) but there isn't a suitable site in our garden, which has very obstructed views of the sky in most directions.

    Cory: if you have a CCD camera already (some of which are really just repackaged webcams, from what I can gather, so not expensive) then all you really need is a laptop and a bit of software. Nebulosity allows live-viewing although to get the richness of colours, you need to integrate an image for a few seconds or more. I seem to recall a product being released a year or two ago which allowed true live-viewing, rather than being geared up for image acquisition, but I don't recall the name. It was trying to bridge the gap between visual and digital astronomy, I think.

  4. Hi Al, David,

    The camera that can be used for visual observations is the Mallincam:

    Never used one, but they have a great reputation.

    Al: how large is your Celestron? My current astrophotography rig is also based on a small refractor, but I'm seriously thinking about an SCT...