Galileo's Camera

As usual my sense of timing seems to be impeccable, I decided experiment with image stacking for deep space imagery when the monsoons are about to start. Ever since I made the decision, it's either been raining or completely overcast. I even had some difficulty in trying to do solar photography. Luck turned my side when I went on a trip to one of the national parks in SL, Wilpattu. The bungalow we stayed in was right in the middle of the jungle with absolutely no light pollution. My brother was the first to spot that the Milky Way was clearly visible overhead. He was trying to experiment with a set of long exposure shots while I was trying to get a series of comparatively shorter exposure shots for stacking. Milky Way across Cygnus (20 frames of 10sec exposure) The image above (Milky Way across Cygnus) was stacked on Deep Sky Stacker using 20 images each with 10sec exposure. The stacking was done with 10 dark frames and 10 bias. The image below captures Milky Way across Sco...

For about a month's time, I wasn't able to do anything interesting on astrophotography  owing to the bad weather. I started some experimentation on solar photography and well that is not going that well either. However, last week I managed to snap some decent pics of the moon. For the longest time I thought that lunar photos do not need stacking or wavelet enhancements. I mean moon is the second brightest object you can find in the sky. For the sake of experimenting, I tried stacking them and doing some wavelet processing on registax. The result is as follows: Moon - 10 frames stacked and processed with wavelets. I was quite surprised to see that this actually did made a difference. Compared to the usual blurred photos I get, these seem to do way better. For the sake of comparison, see the photos below: Non-stacked (prime focus) Stacked with wavelet processing (prime focus) So yeah it does seem to make a difference. I also wanted to see if this was something to do ...

In the last post, I wrote about what is collimation and what sort of an effect a non-collimated telescope has on imaging. Taking it from there, let's see what are the equipment we can use in collimating a telescope. No-Tools: Firstly let's ask the question whether we can collimate a telescope without almost any tool. It is possible for someone with real good patience and a reasonable eye-sight could collimate a telescope that is not seriously misaligned just by star-light (point at a star, keep adjusting up until the slightly out of focus image stops being an ellipse and becomes a disc). However using a collimation cap makes the job much more easier. It is not necessary to collimate the telescope during the night when using this method. It is possible to perform daytime collimation by center-spotting your primary mirror. What is center-spotting? It simply means marking the exact center of the primary mirror. Some of the telescopes come with the center marked from the factor...

For any reflecting telescope, collimation of the optics is one of the most important and regular tasks. Collimation simply refers to aligning the primary mirror and the secondary mirror along with the eye-piece. However, the job it self is not that simple. If a telescope is not collimated, the image it creates would not be in the same plane as the eye or the projection plane (in case of a camera/ccd/projector is used). This could lead to various ring patterns, distortion of the image to appear when viewed. This means that even when you have focused the image properly (or brought the viewing plane up to the focal point), the image is still not clear/smeared. Fortunately, this it self provides an easy way of identifying whether or not a telescope is properly aligned. Ray diagram of an uncollimated Newtonian - Red line depicts the plane where the image is created. The green line depicts the viewing plane. To try to understand what happens in an uncollimated telescope, let's ...

We are going through the monsoon season again, and well needless to say, not a very great period for astrophotography. Had somewhat of a clear sky today and decided to snap some quick photos and stack them using Deep Sky Stacker. Crux - The Southern Cross In the image above, in the thumbnail view, the main stars of crux is quite obvious. However, when you see the full sized image, you will see that the image is pretty detailed. The top most star is Gamma Crucis. The right most point of the cross is Delta Crucis. The brightest start of the constellation is Alpha Crucis, or the bottom-most star in the constellation. However what interested me was Mimosa (or Beta Crucis), the left most point of the cross. The open cluster NGC4755 resides close to Beta Crucis. This being my very first deep sky imaging attempt (or at least the first decent one), I did not expect much and kept shooting with my 75-300mm lens on a 550D. NGC 4755 Obviously the shot isn't great. But I believe ...

With all the preparation yesterday and day before, I was quite hopeful that I could get a few decent shots of the transit. I was specifically planning for one good shot through the telescope and a time-lapse shot of the transit across the solar disc. So imagine my delight when I work up today morning and found this greeting me: So much for the plans of scope photography! Managed to capture this during the small time sun was visible, and had it not been for that, my plans for the next century might have needed considerable reconsideration. Transit of Venus - 06 Jun 2012, between 09:10-09:15 local time Sri Lanka

Just a quick post on viewing the transit of Venus tomorrow: Timing You can find timing related information from http://eclipse.gsfc.nasa.gov/transit/venus/city12-1.html and http://eclipse.gsfc.nasa.gov/OH/transit12.html . For those of us from Sri Lanka, the transit will be visible from the sunrise it self. The peak of the transit would be around 07:30 AM. The transit will end around 10:21 AM. The latter link actually has a nice image of the path of Venus across the sun. Viewing Do not use sunglasses or xray film to look at the sun. Most of the damage that happens to the eye can happen due to the wavelengths which are not visible. If you do have xray film and a camera/webcam with a reasonably good zoom, put the xray film in front of the lens and use the live-view of the camera to view the transit (or you can hook it up to a laptop). It is also possible to use a pinhole camera to project the image of the sun to a wall. During 2010 annular eclipse, I came across a natural pinho...