Meade 8" Dobsonian enhancements
The Meade Starfinder Dobsonian reflector is a classic telescope. It has a lot of good features such as a decent Primary/cell, secondary spider, and good quality 26mm Super Plossl eyepieces, but that is about it. The rest of the design is economized to make it a marketable item. I found with a few enhancements the telescope can achieve a very fine optical standard for it's size. The following is a rundown on the enhancements I have performed on it. There are some others I intend to do, and there are some that are not shown such as the finish painting of the primary and secondary mirror edges and the cell. I have also added a foam board cover over the vent holes to keep the dust down and it can be removed easily as it is attached with Velcro tabs. Recently, I added some internal baffle rings to the OTA, and this has helped to minimize internal reflections. It was a difficult job, but worth the effort. I don't have shots of the addition yet, but hope to soon.
I do not endorse this for everyone and it must be noted that the modification of the telescope is a bold step that should not be undertaken lightly. If you are in any way skeptical of your abilities to do the modifications, I would recommend getting help and advise from your local telescope dealer before proceeding.
It also should be said that the best enhancement any Newtonian reflector can benefit from is a good set of collimation tools and skills. I use the AstroSysytems AstroBeam laser collimator, Light Pipe, Sight Tube, and AutoCollimator. A mechanical collimation with the light pipe, sight tube, and autocollimator is done first to assure that the optical pathway is true, then the laser collimator is followed up to fine tune the system, and to use in the field.
This is the 12VDC fan that moves air across the primary mirror and out the vent holes on the other side of the OTA. The effective enhancement is dual purpose. It speeds the cooling down of the primary mirror and acts as a foil to the thermal currents that linger on the front surface of the mirror. The enhancement is dynamic. It is the biggest help of all the enhancements. I was skeptical of the effects until I performed the modification, and the results are drastic. Well worth the $20 spent.
This modification was done with felt board from the local craft store, some Velcro strips and spray on glue. (be sure to remove any optics before using the glue!!) The felt board was glued to the opposite side of the OTA from the focuser in line behind the secondary. It acts as a black background in case light shines on the inside of the OTA, it will not present any glare around the secondary. (notice the paper tab on the felt. It is a sight tab for aligning the focuser at 90° to the OTA) The extended light shield is removable as it is attached with a band of Velcro hook around the OTA. The shield of felt board is simply wrapped around the tube and it sticks well enough to stay put even in a wind!
The rest of these enhancements are more oriented toward the "observing tools" region. The solar aperture mask is home-made as well as the focuser mask. The solar mask is the same as the plain aperture mask except for the Baader filter film, so I just showed it. The focuser mask has a plastic food wrap cover on it that I use for a dust cover when the telescope is stored. These are very handy and are made by Saran(TM) and are called "Quick Covers"(TM). I use the 14medium size for my 8" reflector. The bottom two pictures show the JMI Mini3 focuser with the extender tube, 3x Barlow, and 26m Super Plossl eyepiece, and the other shot is of the Telrad finder. Both are a major help and upgrade from the Meade equipment supplied.
Celestron 80mm f/11 refractor guidescope on a Meade LXD300 equatorial mount.
The use of piggy backed cameras on a German equatorial mount is a very popular way to get wide-field shots of the night sky. I have been pretty well limited to this technique as the prime-focus work I do is not using any tracking telescopes. I have not purchased an off-axis guider from Lumicon yet, and the Meade 8" Dobsonian reflector is no good for anything other than the Moon.
So as a consequence of the above constraints, I have learned to use the piggyback method to get high power telephoto shots. The picture below is of the equipment I use to counteract the motion of the Earth. The mount has a single axis Right Ascension drive motor, and the Declination axis is still hand controlled. I use a Meade 12mm MA illuminated crosshair reticle to guide the camera and telescope on a guide star. The mount contains a polar borescope to aid in rough alignment to the celestial north pole. The aluminum legs have been replaced with wooden legs that came from the Alt/Az mount supplied with the Celestron refractor. This is a major help.
The camera shown is my Canon TLb 35mm SLR. It is equipped with an 80-200mm Vivitar zoom lens. The camera I usually use is a Nikon Fm 35mm SLR with either a 75-210mm f/4, 80-300mm f/5 zoom, or a 500mm f/10 Maksutov/Cassegrain mirror lens. I also have 50mm lenses and 24mm and 28mm wide-angle lenses for wide field work.
The most difficult part of the whole setup is the polar alignment. I use a drift method if I need to do high power work. This has been the hardest procedure to learn to do well, and after weeks of frustration I have concluded that the mount and gear drive are just a bit under the task. People spend a bunch of money on good mounts and the sample pictures on my photography page are the reason why! (They exhibit a great deal of drift). I will have to go that route some day, but this has been an invaluable lesson in hard work if nothing else. I admit I am a glutton for punishment.
This is the same mount after I tried some stabilizing tricks. The wooden legs were from the Celestron Firstscope 80 Alt/Az package. The 8" foam board spreader , and the chain at bottom add stiffness to the tripod. The addition of lots of Velcro stick-ons, help to give me places to attach the battery pack and hold the paddle control. Simple additions that have made a world of difference.
