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12" flextube dob first light


iamjulian
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The scope.

Bought the 12" Skywatcher flextube dob (not GOTO) from Evergreen Optics, who are local to me, and who offered to better the price of the other main online retailers. Arrived within a couple of days, despite the heavy snow. I had seen plenty of photographs beforehand, and knew the dimensions and weight, but it still took me by surprise when I opened the OTA box. Compared to my old 150P it is a monster. The OTA didn't need any assembly, it was the base that took about 45 minutes construction. All the tools were provided and the instructions were clear with only a couple of obvious blunders. I assembled the base in the back room, which is between the back garden, and the garage where it will be stored. The door to the back garden is plenty wide enough, but I had to tip the base at a slight angle to get it into the garage. It isn't ideal, but at least it does fit through. I am glad I got the 12", but if I had done the sensible thing and seen a 10" and a 12" in the flesh, I may have opted for the 10" due to its weight and size. Ah, who am I kidding :)

First light.

After exactly two weeks wait, the first clear sky came last night, so I put the scope outside to cool. The garage isn't much warmer than outside, so by the time I had eaten my tea I guessed it was ready to go. There were a few clouds about threatening to spoil things, but they soon disappeared leaving a moonlit sky, albeit not one with very many stars showing. I could see to perhaps about mag 4, where it is more often pushing 5. Step one was to get the right angle finder and scope aligned. For this I used Betelgeuse as there was no chance of looking at the wrong star, due to its colour. The rest of Orion was too low to have a look at and was rapidly disappearing behind the house. Right out of the box the scope and finder only needed a very small tweak to get them aligned, and despite the various journeys and some test assembling, the scope was collimated pretty well spot on.

First thing I noticed was that while the altitude was controlled very easily with the brake, but when the assembly instructions said not to over tighten the bolt that holds the azimuth bearings, I was too cautious, and as a result only a gently push was needed to spin the whole thing through 360 degrees. Oops. That is going to be the first modification because I spent the rest of the night whizzing back and forward trying to follow objects at high power.

Second thing I noticed was that using a right angle finder with a dob is a waste of time. It may be better for the old neck, but it's useless if you actually want to find anything. I found myself looking along the line of sight to get the finder in roughly the right spot before actually looking through it. The red dot finder may have to come out of retirement, though the right angle finder was much better than the little finder on the 150P. It was definitely more difficult to point the dobsonian at the right place in the sky than it was with an EQ mounted telescope. A sensible finder will improve matters, as will practice at moving the thing.

First messier object.

The moon was about 80% full and creating a big shadow on the garden so I knew it was a waste of time galaxy hunting. Auriga was nice and high so I decided to look for clusters. I dropped easily on to M36 in the finder, an obvious grey smudge, and once centered I had a peak through the scope. I can see why Messier included it - through the finder it is definitely comet like. But through a telescope it isn't exactly the prettiest cluster. In my humble opinion. M37, however, now there is a nice cluster! Definitely plenty more stars than my last view of it. I was using a 2" 32mm EP so 46x magnification and it fitted nicely in the field of view.

The moon.

I couldn't resist a look at the moon, so I swapped to my favourite EP - wide angle 6mm skywatcher plossl, which I got for £12 from SGL classifieds, giving a magnification of 250x. This is the most magnification I ever used on my old scope and it rarely managed to cope with it, perhaps because it needed the 2x barlow too. The 12" without a barlow took 250x with ease and I couldn't believe what I was seeing. The moon's features were completely 3D. I could see craters with faults in them where the rim walls had slipped. I could see hundreds of tiny craters within larger craters. Central peaks within craters. And I could see what looked like wrinkles or fault lines on otherwise flat areas. I know very little about the moon so please forgive my terminology.

Jupiter.

The planet was temptingly placed in a gap between my house and next door. I was going to leave it, but took the opportunity to try moving the scope and base in one go. Doable, but not easy and had to almost drag it about six inches at a time, out to the middle of the garden where Jupiter was in view. The air currents over the flat roof are always bad, which is a shame because it is my only view of the southern sky from the back garden. That said, at 250x magnification, despite the shimmering disk, Jupiter was clearly showing bands and its moons were much brighter than I had previously seen them.

Andromeda.

I wasn't going to look at any galaxies, but I couldn't help giving myself a quick look at Andromeda. Considering the moon was about 80% full, and considering the moon was somewhere near Triangularum, so not far away, I was amazed I could find it at all. But at 46x magnification, I not only found it, but it filled the eyepiece side to side and was the best view I have ever had of it. I cannot wait to take a look under a dark sky!

I was only out for about an hour because I had other things that I needed to do, but I have seen what the scope is capable of and skies permitting I will be able to have some some decent time with it over Christmas. The moon was perhaps the biggest revelation of the night and the detail made me want to take out a pencil and start sketching what I could see. Perhaps when it gets a bit warmer and the risk of frostbite has diminished.

Thank you for reading.

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An excellent and inspiring first light report of your new scope! Thank you for sharing it. :)

You are in for a treat with some of the objects you have mentioned. Like for example, dust lanes in Andromeda *swoon*...but M33 has slightly discernable dust lanes as well....the Eskimo nebula is a real treat with it's bright core and a fuzzy/spiky circumference....and of course, the mind-blowing Orion nebula. (the Flame nebula looks pretty good too. :))

Edited by Beulah
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Great review. Its really interesting to read about people's experiences. particularly when its on new kit that is so dramatically different to what they have normally been using. Jumping from 6" to 12" is a significant jump in so many respects and I am really pleased that it is already providing you with dramatic views. One of my mantras for new people starting up in astronomy is always to look through other people's gear, as it will always reveal something that you might not have noticed or even thought possible to see before.

Again thanks for the report and look forward to reading an update soon when you can experience darker skies.

James

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That was a good read Julian - I wouldn't worry about the raci though - it comes naturally after a while, even if it does feel strange at first. But using a telrad is never a bad idea anyway - thinking of putting one on mine. You'll love the scope all the more when it's properly dark :)

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I've had this scope for a couple of years now. It's a real eye opener. Sounds like you must be in range of some dark skies - perhaps you live under dark skies? I regularly drive my 12" out to Dartmoor. Perhaps you should check out some local car parks?

I share your misgivings about the size versus a 10". Mind you the 12 has some advantages like the light grasp and the higher eyepiece. I keep mine in the cardboard box to keep the spiders out and for transport protection. If you are lifting the scope in the box just remember to think about your back! Having owned a 12" stepping down to 10 would be difficult.

I have a right angle erecting viewfinder on my flextube and I'd be lost without it. I wear knee pads when observing, so I just kneel behind the scope, line it up on a nearby star and then switch to the finderscope. I then star hop to the object which I can often see in the finderscope because I'm under dark skies (I'd be lost in light polluted skies). I guess with a red dot finder you'd just have to remember the angle from the bright star? I always keep the cap on the finderscope eyepiece when I'm not using it to help prevent dew.

You are probably going to need to make a shroud and dew shield at some point, although dew seems to be less of a problem at this time of year. Then there are the other usual dob mods like painting the lip of the secondary and a bit of flocking.

Anyway I'm excited for you. There are many wonderous sights to be seen through this scope.

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This was a great read and reminds me of when I got my OO dob.

Definitely get a Telrad. You can often use just this to find target with a wider field EP and when combined with a RACI finder it has transformed my ability to put the scope in the right place and then find things with fine tuning.

I have tried the Rigel Quikfinder but recently sold mine to get another Telrad. There's nothing wrong with the Rigel but I just prefer the Telrad.

As others have said, try looking at Orion you'll be amazed - it's just stunning in a bigger scope. Globular clusters - boy you are in for a treat!

As far as I am concerned virtually everything looks better in a big scope.

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  • 3 weeks later...

Smashing review. Im considering a step up from a 6inch home made reflector so this has been a really interesting read.

I also like what you say about the moon, Ive always concentrated on DSOs so the moon has always been a hinderence but maybe I should start taking more of an interest in it,

regards

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