Standing stone

It’s 50 years since a group of undergraduates from the Cambridge University Astronomical Society had a holiday surveying megalithic sites in Argyll to investigate possible astronomical alignments. It was a lot of fun, and we even wrote it up and the results were published in a paper in Nature 253, 431‑433 (1975) which was probably something of an achievement at the time, though I’m not sure that we realised how much!

We had a great time meeting up and revisiting old haunts in the area.

There has been a lot of hype in the media about this comet, but it was never going to be really bright. I started to think about trying a photo as it approached its brightest, but the weather made this difficult. However I finally got the chance to try properly when the skies cleared yesterday.

This is a heavily processed image, made by adding 26 exposures each of 10 seconds, taken using my 500mm focal length f/4 (approximately) Skywatcher Startravel 102T telescope with a Nikon D3100 DSLR on an alt-az tracking mount. The camera was set to ISO 3200. The image stacking was done with DeepSkyStacker, followed by a little image processing there, then rather more adjustment using Gimp.
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Orion nebula image

In March last year I obtained a photo of the Orion nebula that I was quite pleased with, but later was a little frustrated that my old 3 inch (75mm) aperture refracting telescope was a bit wobbly on my new alt-az driven mount, as it’s so long. I have been trying an assortment of long photographic lenses, but this year took the plunge and got a compact 500mm focal length telescope with a 100mm objective lens.

I have finally been able to try it out in dark skies, and was first of all really pleased by the view of M42 through the eyepiece. A few days later I was able to get the camera on the end of the telescope, and the very first image on the back of the camera had me amazed. It was just a 20 second exposure, but showed so much.

The image above is a stacked composite of 8 images, total 160 seconds exposure, ISO 1600, using RAW format. I fiddled a bit with the contrast etc to get the result here, but I can see that I will have a lot of fun with this setup.

Telescope on tripod

Since we were clearly not going to be able to do our usual foreign travelling this year, I bought what is really a long wide aperture telephoto lens, but is also usable as a telescope, for my astrophotography. It’s a Sky-Watcher Startravel 102 obtained through First Light Optics. I am really pleased with it.

The red glow is from a 12V power supply I made, which uses a 4 cell LiPo battery with a regulator.


I decided that I wanted to try a Bahtinov mask for focus tests on the 3 inch refractor, after having tried one on a telephoto lens with some success. The Moon was about so I thought it could be a good test. This image is what I managed purely by using live view to focus. The live view was monitored on a tablet, by using the HDMI output from the camera, and a video capture dongle. Continue reading

M44 Praesepe

Yesterday’s image of M44 Praesepe, or the “Beehive” cluster. This was taken using my old 135mm Pentax fitting lens, with a mild Barlow in the Pentax to Nikon adapter. I use it because it’s faster than my other lenses; f/2.8 as opposed to f/5.6 on a telephoto set at 200mm, or f/4.5 on a zoom set at 70mm. The image quality is not as good as that from the Nikon zoom set at 200mm, but exposure times are much shorter. I need to be patient!

The image is from a total exposure of 240s, and (at last!) with a flat field applied. I took a set of twilight sky flats for all my lenses, so that I can do more experiments.

Whole moon image

Yet another clear evening! A new adapter for my old Pentax fitting lens had arrived, so I was keen to try that; however I had also found an ancient eyepiece for a microscope that fits in the camera adapter for my old 3 inch telescope, so this is a photo of the whole Moon taken with that setup. Continue reading