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.
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
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
Yet another unexpected clear evening – these weather forecasters need to get their act together. I’m not complaining about the clear sky though as it meant more tests. Here’s the open cluster Messier 35. Continue reading
An unexpected clear evening (the weather forecasts are hopeless at present) meant a happy couple of hours testing the telescope drive for photography, with some success. The header image is the Orion nebula (M42), which can be compared with the previous version of this posted on 27 February. Continue reading
After playing around with odd astronomical photos over the last few years (lunar eclipse, comet Neowise, various planetary conjunctions) I decided that I needed to make things a bit easier.
Mars was passing fairly close to the Pleiades this year so a clear night gave an opportunity for a photograph, and a test of my new alt-az drive as a static camera mount. Continue reading
A nice clear night meant a chance to try out my nice new camera / telescope drive (alt-az) as a static mount. This photo was taken with a telephoto lens, 200mm fl, f/5.6, 1/2000 sec exposure, ISO 3200. I still need to do lots of playing around with settings to get the best results.