The OTA is mounted on a CG5 computerized Go To Equatorial mount which makes the most powerfull piece of the complex as it can easily hold much heavier OTAs on.
The Tripod is a very heavy and stable steel tripod equivalent to a EQ6 one.
The instrument passed preliminary testing with flying colours.
Star Test executed on Altair shown a sattisfactory colimation of the mirrors from the factory with well concentric cycles around the black spot of the secondary mirror.
Panetary Test: So far executed on Jupiter only due to limited visual options from the urban position.Jupiter was shown very well contrasted on low and medium magnifications 60x,120x,166x and maintained a good contrast even on 333x magnification without filters of any kind.
Deep Sky Test:Will be performed in the next 2 weeks under the Dark Sky of drassa and hopefully under the Dark Sky of the Kryoneri obervatory near Drassa.
Moon:Excellent View well contrasted on any magnification level,slight a cromatism detected same as in Jupiter due to atmosferic conditions ( large city sky, polluted both by particle inquinants and artificial illumination.Again no filters used.
Soon will be added the Star Test and more extensive planetary test results!
Telescope Number 2 is soon on the way , different OTA , dfferent mount ...more news as they come!
Have a nice summer!
CELESTRON C6-SGT-XLT PART 2
Here we are after the summer period with a more complete review on this instrument.
Once set up the Telescope under the Dark Sky of Drassa at the end of July 2009 and executed a 2 Star Allignment the first thing to do was to verify the collimation. The Telescope had on it's Back an entire trip by car and sea from Rome to Athens and Back to Drassa..over 1000Km of car driving. the Star Chosen was Altair again for it's almost vertical position during the time of the test.
Surprisingly the OTA had supported the trip very well with no evident missalingment of the secondary mirror on a quick test.
Right after first check the test has been rechecked on 2 more stars lower on the horizon, this time the much dimmer Polaris and the brighter than pollaris Arcturus.
Primary test confirmed that rough collimation was well preserved right after the trip and on a secondary star test on maximum magnification we had the chance to reconfirm the same result
The Star disk would present itself both in intrafocal and extrafocal with well separated concentric difraction rings and a nice black spot of he secondary in the midle.
Astigmatism and color aberations were absent.
The outcome gave me a nice sattisfaction about the durability of the collimation on these medium size SCTs and SCTs in general as well as a nice surprise about the perfect factory collimation. The first true correction on the collimation has been necessary to be made the month of October 2009 after another 1000+km trip back to Rome where the telescope needed turns of 1/20 of the collimation screws.A minor collimation but with significant value in High resolution planetary photography and observations on every SCT Telescope.
But lets return back to Drassa and our Telescope test.
A more extented Planetary Test was possible fo be made under this wonderfull sky mostly by the enormous FOV provided by the geographic position and the relativelly Dark sky.
Jupiter even if relativelly low on the horizon was dominating the Greek dry and clear night skies and indeed it would offer splendid views.At 60x the planetary disk with the major bands was visible acompanied by it's four major satelites.At 120x the 4 major bands and more details would be visible but the real show would start from 166x and more where most of the details would be visible including the great red spot and some darker spots on the atmosfere , at 333x we reached the maximum usefull magnification allowed by the seeing ( anyways we were very close to th 354x max usefull magnification specified by Celestron) still with decent results in contrast where we could see some darker layer blue areas between the bands of the Gas Giant.A really great result on the contrast of provided by the C6 and the generous Seeing.
No filters were used.
Uranus:We did not missed the opportunity to use the good seing conditions (the trasparency was less good by the way but still decent ) for observing Uranus of course...allways on a race "hunting" Jupiter.Considering the magnitude (6.00) and the distance its a planet that could be tricky to vew from a lght polluted citty sky.
In this case at 60x the goto brought the planet right inside the eypiece FOV near the center of it.It would be as faint and no much different from stars of the same magnitude.By augmenting magnifications of course the scenario chances drammatically as the Planet starts to increase in size...something that stars do much less in proportion. At 250x colour would start to become barely visible but at 333x would definatelly reveal its nice light blue color.
The Moon was splendid in all magnifications and offering magic views allways, no filters would be necessary to observe and no colour aberations would be noticed again.
Later during August we staid till the early morning hours so we could check for the first time during 2009 Venus and Mars right after Pleiades(which offered oustanding views at low power magnification)very very low on the Horizon.
Venus would present itself very bright and would show it's moon phases very clearly a splendid view considering the low sky hight.
Mars bright as well but deffinatelly much more difficult to focus.Too low to be able to pretend much from the Telescope we managed to observe the characteristic Red colour of the planet alternating with the Bright white of the Polar caps but not more.Remember those are objects of the winter sky.
Extended Deep Sky Test:
We were waiting this period exactelly for performing finally some deep sky observation and here we are:
Double Stars: The first Binary system to center was of course beta 1 e beta 2 Cygni or the otherwise known famous and beautyfull Albireo in the Cygnus constelation. very easy to separate at 60x providing a pleasant view with it's characteristic double colour.
Then we turned the telescope towards Vega and went hunting a more difficult system the "Double-Double" Epsilon lyrae. The telescope provided an excellent view and managed to separate the star easy at 100x even if they would result close. At 120x the view was stunning.
Last we checked the Gamma Delphini in the Delphinus Constellation a not difficult to separate binary even at 70x and the particular Enif with it's companion separated at 60x but really fantastic at 120x and 166x.
Observations were done with the Standard 25mm E-lux Eyepiece (60x) the 9mm Celestron Omni eyepiece (166x) and a very good for it's money TS 2x-1.5x modular Barlow lens.
As a conclusion this OTA performs in an exemplary way on Double star hunting by separating in low magnifications most of the easy-medium binary systems and giving stunning views in medium magnifications on those.We have no doubt that it would perform in the same way on separating tougher binaries but as the night would go on we had to move also on other Deep sky objects.
Open Clusters:If there were some open cluster that someone should not miss during August night sky one of those is definatelly M39 an open cluster of 4.60 magnitude.At 60x it would present itselft in the 25mm 52grade ploessl eypiece.A real jewel with countless stars among its brightest ones as it is almost vertical at 00:00 during August, at the constelation of Cygnus.
Same result for the splendid M29 that would resolve in a myriad of smaller stars among it's yellowish major stars that form it starting from 60x.
Galaxies: We targeted also the beautyfull M31 (Andromeda Galaxy) which shown a very bright core and nebulosity with stars on higher magnifications.Its too companion galaxies M110 would be detectable on medium magnifications and M32 with no filters on higher magnifications would be of course detectable as a bright extended nebulosity.M31 during that period would not offer the best views due to the low relative altitude on the summer sky.
The observations were made with no filters and with the 2 52 grade eyepieces plus the barlow. That would of course penalize larger field Deep space Observations but still brought some great results considering the enormous 2,58 grade of spread of this Deep space object.
The CG5-GT Computerized German Equatorial Mount.
This mount provided by Celestron with the SCT advanced GT series mechanically is a 1.5 kg heavier "clone" of the Vixen GP. on a very heavy and stable 2" still Tripod equivalent of the EQ6 mounts.
It is motorized with 2 DC warm gear servo encoders on both RA and DEC axes.
A CPU and a hand controll with a vast 40.000 objects Database make possible the control of the robotic Go-To system.
Alignment is possible with all the Nexstar methods . The mount has a port for use of an Autoguide CCD for long exposure astrophotography,another port on the Hand control for controlling the instrument via PC and it is also flash upgradable.
It is also possible to connect a dedicated GPS module for making faster the allignment process.
In general the CG5GT is a very steady Computerized equatorial mount that can be a reliable basis for astrophotography even with larger systems than C6 like a C8 that would be it's best apperture even if some do astrophotography even with C9,25 OTAs.Here we have to underline that this mount it is indeed provided even with larger aperture OTAS up to C11" but our personal opinion is that higher than 9.25" will be a valid option only for observation while astrophotography would suffer because of the use of the mount near it's limiting parameters.
Once we made a rough polar allignment (the polar scope is not included with the mount and we find this a con even if not a grave one.) and then alligned with a 2 star aligment the system we found out that the system has a very precise and smooth Go-To even if very very noisy during the star hoping at max speed.During tracking is completelly silent and precise.We did several trials with precise polar aligments and calibration stars and we constated extra improvement on tracking which makes it a very good choice both for High REsolution astrophotography and Deep Space prolonged exposures both with CCDs and DSLR cameras.
The addition of an autoguide CCDs make it ideal for Deep Space astrophotography within it's range of weight carriage.
The mount does suffer of backslash like all others and of Periodic error but withing the average of the mounts of it's class.Backslash can be minimized almost to zero with the antibackslash utilities provided with the Nexstar protocols and Periodic Error even if apparently there is no PEC (Periodic Error Control) included in the HC catalogue there are reports of users that managed to do corrections with 3rd party programs.Cone error correction is available as well as a mount calibration routine and the famous All Star Polar Alignment routine for a precise polar alingment of the mount.
We did not liked the fact that the cover of the DEC motors touch slightly the DEC block lever during rotation but this is something that does not affect the normal funcion of the mount.
Vibration test with the SC6 mounted on the mount proved a time of a second or less till exctintion which makes the system extremelly stable and valid for its purpose.
After these primary tests and almost 6 months of use of this Telescope i came to the conclusion that is is an excellent all around instrument for the average "evolved" amateur observer/astrophotographer and an excellent system for doing advanced High resolution and Deep space astrophotography with a "contained" initial budget.(Serious Astrophotography is not a cheap hobby with any kind of instrumentation).A telescope that can be upgraded and paired with a nice apocromatic short refractor for wide field astrophotography in parallel with both CCDs or DSLR cameras,a solid base that can handle easily heavier OTAs too if someone wishes to pass to a more powerfull OTA.
The standard 1.25" diagonal instead even if it is...exactelly what states to be...."Standard" and works decently we consider that it limits the final outcomes of the OTA because of its..."standart" quality and works like a bottle neck.We advice to change it with another dielectric or high light transmittion diagonal 1.25" or 2" .
Last but not least we have to say that the OTA presented itself extremelly bright and here except the apperture the Starbright and XLT coatings on all optic surfaces must must be doing a great job.
In overall it is a consolidated trustworthy proved over years of use by many many astrophotographers and observers mount that provides a very reliable base for an astrophotography system with SCTs and other OTAs in parallel withing its carriage weight.
A best buy for it's class and for future possible use.
Celestron C6S-GT-XLT Telescope arrived!!!