Coming back from a short break in Devon I was pleased to find the tripod and accessories for the Astrotrac had arrived.  It was also good to find that all the threads were compatible with fixing the Astrotrac to the tripod and the Canon 40D to the ball-head fitting. Read the rest of this entry »

Well it has rained and/or been cloudy every day since the Coathanger image was taken.  You can almost believe there is a higher order deliberately out to frustrate the fun I can have with the new Hyperstar III.  Never mind, if I can’t work extra-terrestrially, it will be panoramas and macros with the Canon 40D. Read the rest of this entry »

The Robofocus guys are getting a new website together and asked for photos of the Robofocus on customers’ systems.  This is how the Robofocus looks on my Tak Sky 90 which is piggy-backed on the Celestron Nexstar 11 GPS.

The only modification I made was to beef up the supplied aluminium motor mount with a 2mm thick aluminium stiffener plate which runs along the top.  The whole mount is now extremely rigid allowing fast, fine focusing.

Two weeks ago I bought a Canon 40D DSLR camera for terrestrial work.  While playing with this beast it struck me that by using the same mosaic techniques that we use in creating big deep-sky panoramas – we could actually create gigapixel images! 

Why should we want to do that? 

Well, one reason is that we could print out very large images at extremely high resolution – something that wouldn’t have been seen before – so this might have some interesting effects on the eye-brain system.  Secondly – if kept on the computer monitor – you would be able to zoom in to see incredibly small detail. Read the rest of this entry »

At 8.00 a.m. this morning an upgrade to Photoshop CS3 arrived.  Within half an hour I was creating mosaics from frames that Photoshop CS2 simply couldn’t handle. 

The image below is a 15-framer, stitched together perfectly by CS3. 

This upgrade to Photoshop is going to be a great help in stitching together deep-sky images, and high resolution Moon shots!  If you produce mosaic images and you use Photoshop, you really should consider this upgrade.

When I originally bought the Celestron Nexstar 11 GPS Schmidt-Cassegrain reflector way back in April-May 2002, I did so because it could use the highly innovative Hyperstar lens, and at that time there was no Meade equivalent.

The Hyperstar is in my opinion a totally brilliant Celestron concept and an extremely brave move on their part as they would have known about the considerable problems with properly aligning the lens assembly, and the potential customer dissatisfaction with the product.

The Hyperstar is basically a 1x field-flattener lens assembly that takes the place of the secondary mirror in a standard Schmidt-Cassegrain telescope.  Your CCD imager sits on the end of the Hyperstar and this creates a very strange looking beast indeed.  I must admit, I fell in love with this thing before I even started Hyperstar imaging; this looked so extreme and really piqued my curiosity.

Since you now have your imager at the secondary mirror position, it is clear that the focal length you are working at is very much reduced, the light does not now go all the way up to the secondary mirror, and then all the way back down the telescope again to come out at the normal eyepiece position.  So the Hyperstar basically turns a very slow f#10 optical system into an unbelievably fast f#1.85 astrograph – an incredibly good idea.  Read the rest of this entry »

In a few of my posts about imaging you will see me mention “narrowband data” and words like “OIII” and “H-alpha”.  Well, this is to do with narrowband light filters and line emission sources of light [as opposed to broadband emitters].  For example from the Veil Nebula Project:

The last RGB image of the Veil nebula has been significantly improved by adding some H-alpha and some OIII narrowband data as can be seen in the accompanying image.

And from the IOM September 2007 post on M31:

Deep exposures of M31 will show up lots of very nice little HII regions in the arms.  You can “boost” the appearance of these regions by adding some H-alpha data to your RGB data.  Take around 4 hours or so of deep [20 minute sub-exposures] H-alpha and incorporate into your RGB data using the techniques discussed by either Steve Cannistra or Rob Gendler [see the blogroll links]

So what types of narrowband filters are there?  The main [line emission] filters used in narrowband imaging are:

• OIII – Doubly ionised Oxygen
• H-alpha (or HII) – Singly ionised Hydrogen
• H-beta – Another Hydrogen line
• SII – Singly ionised Sulphur

These filters differ from each other by the wavelength of light that the particular filter will let through.

Read the rest of this entry »