Archive for Reflector

Mare Tranquillitatis in color

Posted in Astrophotography with tags , , , , , , , , , , , , , , on 2009/09/11 by computerphysicslab

Color contrasts in the Moon are interesting even beautiful. The following picture shows Mare Tranquillitatis area and the southern part of Mare Serenitatis in full color. It was taken 4 days after full moon. The shadows in the terminator show the orography of the landscape. Mare Tranquillitatis seems to be mainly blue. This is due to its peculiar chemical composition.



Posted in Astrophotography with tags , , , , , , , , , , , , , , , , , , , on 2009/09/09 by computerphysicslab

Pitiscus, Hommel, Ideler and Spallanzani are the only four craters of the picture with proper name. The rest of them are named by letter surnames like Ideler R or Ideler L. They are located in the South-East area of the Moon. The picture was taken on 2009-09-09 05h 20m U.T. and the terminator was passing across Pitiscus, Hommel, the two big and shadowed craters. Pitiscus is 85 km wide and Hommel is 129 km (76 miles). The smallest craters of the image are 7 km wide, that is 3.5 arcseconds, 1.75 arcseconds for the bright spot and 1.75 arcseconds for the shadow spot. Image detail could then be better for a 6-inch telescope (this is the equipment used to take the image, an scope capable up to 0.7 arcseconds of resolution). 622 subframes were recorded with the Manual-Crazy-Tracking system and stacked in Registax 5.


Big Jupo

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , , on 2009/08/27 by computerphysicslab

I have a good seeing last night. So I got my best Jupiter yet. Here it is:

Jupiter 2009-08-26 Sharp

It is 4x resampled via Registax Mitchell and PS. After resampled I can spot more details in bands and polar zones.

As always I used the 6-inch no-EQ mounted newtonian reflector, the 14mm eyepiece doing afocal projection over the Canon EOS 450d (Rebel XTi) body and recording video using “EOS Camera Movie Record” free software. Three times Jupiter crossed over the field of view. Registax and VirtualDub added and stacked the footage properly.

Jupiter Opposition

Posted in Astrophotography with tags , , , , , , , , , , , , , on 2009/08/17 by computerphysicslab

15th August 2009 was the day that Jupiter reached its closest position to Earth. Its apparent diameter was 49 arcseconds, so this is the best time to do planetary astrophotography with the giant planet. Using the afocal technique and a Canon EOS 450d body I took 2 video sequences and processed with Registax 5, Photoshop & Pain Shop Pro.


My best Jupiter so far

Posted in Astrophotography with tags , , , , , , , , , , on 2009/07/26 by computerphysicslab

My 6-inch reflector working over a photographic tripod, and a webcam recording the focal plane. This is the resulting image, once overprocessed, yes, I give you that.

With Registax 5 I stacked 150 subframes and then applied dyadic wavelets. Some retouching with Paint Shop Pro 9 and fractal zooming under Photoshop.

The footage corresponds to 2009-07-26 at 01:44 UT.


Webcam astrophotography

Posted in Astrophotography with tags , , , , , , , , , , , , on 2009/07/24 by computerphysicslab

Tonight I have been able for the first time to use a webcam for doing astrophotography. The best up of it is the possibility to get a sharp focus looking at the laptop screen while correcting the focus. Besides, the resolution seems to double that of my digital pocket camera with the afocal technique. Up to now I haven’t got full resolution of 640×480 with my webcam, a Philips Toucam Pro (PCVC 740K). The drivers for XP are very naughty. I can only record 320×240 frames so long.

The down is the small field of view because the CCD sensor has not so many pixels like a digital camera. To find the target with a non-tracking mount is difficult. Here we see a prime focus shot that shows the Galilean moons and a Barlow 2x show showing the horizontal bands of the planet.


Meade Lightbridge smoothness

Posted in Astrophotography with tags , , , , , on 2009/05/05 by computerphysicslab


Thanks for posting that cool vid of the 16″ Lightbridge. I just spoke with someone at a telescope store who said they were looking to get rid of their 12″ Lightbridge because they said it is very shaky when viewing, and gives an unstable image.

I just was in a shop which had an 8″ Lightbridge and I would describe it as very smooth and rock solid.

Can I ask you if you’ve had any shaky or bouncing issues with your 16″?

I’m thinking of the 12″ for myself!

Thanks, PK


Meade Lighbridge does not come with slow motions for altazimuth movements. If you compare the movement of the Lightbridge with that of a tripod mounted refractor, for example, probably the tripod mounted is going to be much precise.

Nevertheless, it depends too much on what kind of observation are you planning. Watching the Moon, Lightbridge may became very smooth and exact in movement, because you always have a bright lunar surface all over the field of view and the movement you apply to the optical tube is constantly compared to the drift as seen through the eyepiece. On extensive deep sky objects, the same happens. The most difficult objects to track are planets, because the surrounding field of view is pitchblack and you lose any references once the planet gets out of the field.

If you try to use high power eyepieces with small apparent field of view with a planet, the lack of equatorial mount and a sideral motor drive may become a nightmare. In this cases, my advice is to always use widefield eyepieces and reduce the magnification if necessary.

To get a smooth movement it is important to balance correctly the optical tube, adding some magnets at the bottom side of the tube, near the mirror. Do not forget to check that the base of the dobsonian mount is not tilted. Following these advices, the telescope will have a very smooth movement in both axis, as shown in my video at

The tracking becomes more difficult as longer the focal length. So Meade Lightbridge 16″ is the most difficult to track, because a slight movement in your hands transforms in a great movement in the field. Lower aperture telescopes, have less focal distance and apparent movements in the field are smoother.

If you are planning the use of the telescope for observational purposes, you won’t have any problems with the smoothness of the tracking once you get trained in several sessions. If you plan to do astrophotography, dobsonian movement may become a problem. Nevertheless, I do astrophotography of Moon, planets, and stars through my Meade Lightbridge 16″. You may check it out at my webpage:

My final advice is: if you have previously be using regularly a smaller scope doing astronomy, you won’t find any problem using any of Meade Lightbridge series. Collimation is an important point to deal with in this scopes, but the quality of its elements is superb, and the price is really good.