Tag Archives: synta

Celestron Nexstar 6E

Well after much soul searching (and wallet checking) I finally made a decision on purchasing a new telescope. I was dead set on the HEQ5 Pro with a C8 OTA, but finally decided against this due to portability issues (and lack of funds!).

That left a fork mount. The CPC800 seemed favourite but I just can’t justify the near £2000 price tag. The alternative was the 8SE however I had some concerns about the mount stability and portability so in the end I am the proud owner of a brand new Celestron 6SE.

My thinking is that this can be my main ‘scope at the moment and will make a nice grab and go ‘scope to compliment something larger later on. Anyway, it’s not ideal but it’s pretty close to what I wanted and over all I’m pretty happy.

I ordered the ‘scope on Sunday from Steve at First Light Optics and I got my grubby hands on the goods on Tuesday. Fantastic service, especially when I got the ‘scope at such a good price! Thanks Steve! I can’t recommend FLO enough for great service and excellent prices.

The ‘scope came in a single large box weighing 10kg. Straight away this gives you some idea how portable this ‘scope is.

Unpacking took no time at all and setup took about 2 minutes. The OTA came already attached to the fork arm and the only assembly needed was to attach the fork arm to the tripod.

After assembling the ‘scope the first thing that I noticed was that there was a problem with the hand controller. The rubber/plastic sheet the buttons are formed from wasn’t properly seated in the plastic case:

Something like this should have been spotted in Celestron quality control but it wasn’t much of a problem to snap the hand controller open and reseat the button “sheet”.

Lifting the whole setup is a breeze and I don’t think there is a need to separate the fork/OTA/tripod for transport, at least not from my shed to observing location in my garden.

The back of the OTA is very similar to the C8 although I’m not too impressed with the focus knob being positioned directly beneath the visual back (due to the positioning of the dovetail rail). I think this would have been better placed 45 degrees to the lower right, but it’s only a small thing. I may even look at moving the dovetail rail if it gets on my nerves too much.

The lens cap as can be seen is a single piece of plastic and fits well. It’s a pain though not having a central handle like on the older SCT models. Not having this central handle means theres much more chance of touching the corrector plate. I may attach a handle at some point in the future, perhaps just drill a hole in the middle of the cover and attach a kitchen draw knob.

Another niggle is that on the tripod there isn’t QUITE enough thread on the spreader plate bolt to loosen the spreader without the knob coming completely off the thread if that makes sense. This means that in order to collapse the tripod you have to remove the knob completely drop the spreader, rotate it and then reattach the knob. It would have been MUCH easier if they had made the bolt half an inch longer, this would have meant the bolt didn’t need to be removed, just loosened. Hey ho, it’s a small thing and another niggle I can live with.

The SE series has the ability to be ran from AA batteries however this isn’t really recommended as the motors REALLY suck these things dry. I use a 240v mains supply adapter when at home and a power tank when away from home. This means that there is no chance of the batteries running out in the middle of a session. (another!) niggle though is that I had forgotten to “split the pin” on the power socket. It seems that ALL ‘scopes that use the same power socket need the central pin to be split slightly to stop the power plug from falling out mid-slew. Irritating, but easily fixed.

Next to the battery compartment is the 2 ports available on the SE. One is an AUX port for a GPS module and the other is a standard ST4 autoguide port. Although the SE isn’t really designed for imaging i’ll be attempting some widefield DSLR shots when I get the chance.

One of the main draws to me for the SE series is the ability to remove the OTA from the fork arm. The SE uses a (nearly) standard vixen dovetail system and this means that it’s easy to attach a small APO refractor to the mount for a wider field of view. This is something i’ll look into as it’s nice to have the best of both worlds.

Removed the OTA looks very small! I guess it’s a similar size to the Synta 150 Mak. Weight wise it’s not that much lighter than a C8, but the added stability the lighter OTA gives does seem to count. When attached to the fork arm at 300x a sharp rap to the OTA settled in less than a second. A rap to the tripod settled in less than half a second. I’m very pleased as the stability was one of my main concerns with this single fork arm setup.

I actually managed to get a first light on the same day I recieved the ‘scope, a first i think! I put the ‘scope out to cool at about 8:30pm and came back at 9:30pm to see if I could get it aligned. The hand controller is familiar to me having owned Celestron GT/SLT/CG5 telescopes before. I hit SkyAlign and entered my location and time. I then slewed the ‘scope to Venus (nice and bright low in the west), Capella directly above Venus and Saturn (I was keen to see the performance on Saturn). Skyalign sat thinking for a while and then unceremoniously said “Alignment Failed”. Hmmmmm odd. I tried again with Procyon, Capella and Regulus…… waited…… Alignment failed. Grrrrrrrrr, iritating! 3rd time lucky? Nope. Tried Capella, Regulus, Mizar……… Alignment failed. Well I’m sure it’s most likely operator error, so I gave up on the alignment and just slewed manually back to Saturn. There he was nice and bright in the 25mm supplied e-lux eyepiece. Rings very crisp and despite the near 40% central obstruction the view was actually very pleasing and contrasty. I defocused to check collimation and saw that it was off a little (I have a set of Bob’s knobs on order). It was close enough to not bother messing around though. I swapped to a nagler 3-6 zoom and at 6mm (250x)Saturn was glorious. Still bright and clear, although seeing wasn’t good enough to see Cassini (and collimation didn’t help). Just for fun I pushed to 4mm (375x) and Saturn was obviously mushy but still nice and bright. Even at 500x (3mm) Saturn was still clear and bright and overall i’m very pleased with the optics. I can imagine with a perfect collimation and a night of good seeing the images will be as good as anything I saw in my ED100. Which is suprising and probably says more about my eyes then about the quality of my equipment!

Anyway I spent about 30 mins viewing Saturn (manually slewing to keep up as tracking wasn’t enabled without a GOTO alignment) and then gave up for one night. The best bit? Pick the whole kit and kaboodle up in one piece and carry it to the shed. Total time to pack up: less than 30 seconds.

I can see that once i’ve got the alignment sorted out the little 6SE will give me many nights of great viewing, and I highly recommend this ‘scope to anyone who is a visual only observer and wants a lightweight portable GOTO ‘scope with 6” or 8” of aperture.

I’ll add more as I get to use the ‘scope more.

Originally posted 18 April 2007


ST80 vs ST102

I recently wanted to purchase an ST80 or an ST102. I was undecided which to purchase and a wanted advert for an ST80 turned up 2 people wanting to sell me an ST80 AND an ST102. In such a pickle I decided to buy both so I could compare and then sell the one I liked least. I thought I’d share my findings here for those interested.

The ST80 is an 80mm f/5 (400mm) OTA and the ST102 is 102mm f/4.9 (500mm)

Both examples are made by Synta and are in Skywatcher blue. You can see the difference in size isn’t massive, with the ST102 being slightly larger. The weight of both tubes is comparable although when weighed “in the hand” I could tell the ST102 was slightly heavier.

Removing the dew shield revealed the lens cells. The ST80 seems to be made from plastic which perhaps isn’t a bad thing as it makes it lighter but it gives me concerns about the durability of the ‘scope. The ST102 lens cell seems to be a combination of metal and plastic, which is perhaps SLIGHTLY better than the ST80. Neither seem to be collimatable.

Viewing down the barrel the ST80 is well baffled and whilst the lens is coated it isn’t fantastic. That being said these are nice and cheap so I can’t really complain.

The ST102 is equally well baffled, but again the coatings leave something to be desired. I think the ST102 appeared a little better than the ST80 but thats subjective with both examples being second hand (although in good condition).

The ST80 has a cast aluminum 1.25” rack and pinion focuser whilst the ST102 has a 2” cast rack and pinion focuser. (Note the focus wheels on the ST102 have been replaced at some point, but this is a small modification). Both have been regreased but experience tells me that if brought new would be full of “syntaglue”. Easily fixed but god knows what the engineers were thinking when they used this “grease”.

All the following shots were taken with my Nikon D70 DSLR at prime focus. I’ve not had the opportunity to test both ‘scopes at night yet due to the weather (snowing here!).

The test chimney was fairly close, about 300 meters. You can see the difference in focal length immediately with the ST102 giving more magnification from the outset. You can also see that the ST80 image appears to be washed out a lot more than the ST102. I’m not sure if this was a function of the weather or if it’s due to the change in aperture. The ST102 definitely seems clearer though and despite it’s fast f/4.9 focal ratio in these daytime shots I can’t see much colour in either shot. I didn’t get a chance to barlow up to take a closer shot with both scopes but perhaps I need to test in that configuration too.



Taking a 100% crop of both these images from the 6 mega pixel originals gives more information. Again the ST102 seems MUCH clearer than the ST80 and I’m beginning to think that the added resolution of the 4” compared to the 3” lens makes a big difference to the contrast too, at least for these daytime shots. I was expecting the ST102 to show more colour as it’s f/4.9 not f/5 but to my eyes I can’t see much difference. Perhaps some moon limb shots will tell more.

ST80 Crop

ST102 Crop

All in all at the moment the ST102 is winning due to the larger aperture, however the ST80 is still the more portable OTA. Night time tests to follow as the weather allows!

Originally posted 24 January 2007