For a while I have wanted to take an image of M31 using the new(ish) telescope. It’s a great target, and has always impressed me because I know its real size on the sky – it’s really about 3 degrees – or six full Moons – across! We can just about see the tiny brightest part of the nucleus with the naked eye in a dark sky; with binoculars it’s a bit bigger, and in a photograph you start to see its true size. To me it was most spectacular on a thin glass plate image taken with the Schmidt telescope at the Palomar observatory, when I was using photographs like that as a professional astronomer.
This is very much a first try. It is a stack from just three 30 second exposures at prime focus of my 500mm f/5 telescope, ISO 1600. It’s cropped to square, and has a bit of colour curve processing to increase the colour saturation. I had real difficulty getting the alt-az mount aligned (not helped by bright lights at eye level around the field where I was working) and from a sequence of nearly 50 images only a few were untrailed (even though quite a few had very small trails). Next time I will do better!
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.
I have always thought that the Ring Nebula looked very pretty. I had not realised just how easy it is to get a photo of it; this is just a 20 second unprocessed image using my 10cm f/5 aperture telescope, at ISO 400 on my Nikon D3100.
A processed photo is below …
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.
Well that was exciting! The test of a spacecraft impact on an asteroid (actually, a small asteroid orbiting a larger one). The image is of the surface a fraction of a second before impact.
Details from NASA here: https://www.nasa.gov/feature/dart-s-final-images-prior-to-impact
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.
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
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.
After a reasonably successful test of eyepiece projection using my old 3 inch refractor, I decided to try again with a bigger distance between the eyepiece and the camera focal plane. Continue reading