Michael‘s Astrophoto Blog

The comparably short focal length of 525mm provided by the Hyperstar is giving a quite big field of view enabling the fast imaging of objects that are simply too big for the optics I was using before. The C9.25 has a focal length of 1480mm with reducer and 2350mm at primary focus. This is good for smaller objects like most galaxies, but most of the objects I showed in the previous posts simply wouldn't fit in one picture.  I was eager to take picture of all the big objects that I always took off the list before. However, as it turns out, there are still a number of "famous" objects that won't fit in a single image even with the Hyperstar. So, I did bite the bullet and started composing mosaics of multiple images. It turns out that this works quite well, even though the required exposure times grow quite fast with the number of mosaic panels. Here is a first 2x2 mosaic I did of the North America and Pelican Nebula. Each subimage is an integration of 200 frames. My seco...

Last week we had two clear nights. Even though it still was some 25-20% waning moon I decided to image full RGB spectrum - without the narrowband filter.  Many experienced astrophotographers will concentrate on the same object over multiple nights to gather data for very deep images. However, somehow I have not developed that level of maturity yet. I wanted to play and to see what my new Hyperstar optics is able to do. So, I took pictures of a number of nebulae to get a better sense of what could be nice targets for the future. As I had already taken a picture of the "Heart Nebula" I added the nearby "Soul Nebula" as well: The Elephant trunk nebula is a pretty big (and beautiful) object. This is my first image of it. I noticed that the actual "trunk" is relatively small, so it may be worth imaging at a longer focal length. The Cave Nebula an interesting object with many dark nebulosity - fits quite nicely in the Hyperstar frame. The Bubble Nebula is actual...

One of the main open questions when buying a Hyperstar was how it would work with L-eXtreme dual narrowband filter. At f/2.2 the light will no longer be mostly parallel to the optical axis,but will pass the filter at comparably high angles. This will lead to a downward shift in the filter transmission wavelengths. There are filters that are specifically designed to compensate, others just have wider transmission windows to be less sensitive for that effect. However, as these filters aren’t cheap, I wanted to see what I can do with my L-eXxtreme first. Results published by other amateur astronomers vary from "the filter is completely useless at f/2" to "among my many filters the L-eXtreme is the best with my Hyperstar". Apparently, there is a bit of variability in the spectral transmission curve between the individual filter specimens. In my second night of testing the Hyperstar I therefore took a number of images using the filter. As there was rain forecasted in the...

One of the first images taken with my new Hyperstar.  After long deliberation I bought a Hyperstar system for my C9.25 Schmidt Cassegrain. For quite a while I was torn between the Hyperstar and getting a separate refractor. I did a lot of research and in the end I changed my opinion almost on a daily basis. Finally, I decided that the pros and cons of these two approaches are probably reasonably balanced and that I need to try it myself.   If you are not familiar with it - the Hyperstar is an optical system that is put in place of the secondary mirror of a Celestron Schmidt Cassegrain telescope, basically turning it into a very fast astrograph. For example, C9.25 becomes an f/2.2 system with 525mm focal length. The Hyperstar mounted on top of the telescope  Rough Collimation One of the drawbacks of a system like the Hyperstar is that, like all reflector telescopes, it requires some level of alignment i.e collimation of the optical components in order to perform optimally....