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So many stars! First Light on a 10" Revelation/GSO Dobsonian


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I've been looking out for a while for cheap way to sample the delights of larger aperture and have missed out on a few as I was determined to stick to my guns on budget.  In the end I secured an eBay purchase of a 10" Revelation-branded GSO-made f5 Dobsonian.   The 'scope comes with a built in cooling fan that runs off my Celestron power tank, meanwhile the chunky base sports a sturdy carry handle and a handy eyepiece rack. It came with  GSO 26mm "Superview" 2" Eyepiece and matching 1.25" Plossls of 6,9,12, 15 & 20mm. Not bad for 30 quid per inch!

I picked it up on Saturday lunchtime and was excited to see a clear forecast for the evening.   My wife was mildly shocked by the size of the thing :)  I spent the afternoon taking some first steps in the dark art of collimation using a cobbled-together collimation cap made out of the lenscap to the supplied 26mm (involving tinfoil, glue, a paper circle and a compass point, all very Blue Peter).  Initially I kept getting to point where I would run out of travel on one of the Primary screws just as I was getting things moving in the right direction. In the end I started from scratch and measured the full travel of the screws (10 half turns from end to end) then set them all in the middle and worked from there. Thought I had it there or there abouts so popped things out to cool.   

I say "popped", lugged would be more appropriate.  I live in a tall, thin townhouse and have many stairs to access the garden, its not that its massively heavy but the tube in particular is awkward to manoeuvre & could use some handleage. But once gingerly lowered into its simple Alt bearings, the springs to maintain tension locate easily and I was impressed with both the balance and the smoothness of movement.  The Az side is a little bit gritty, may try and clean the track as some point, but nevertheless it swings about quite nicely for its size and weight. 

I'd elected for a garden session as there was tinkering to be done and I am mulling over what kind of wheels might be needed to get me to the spot in one of my darker areas. (Besides which it was Saturday night and a nice glass of red accompanied my session...). 

I picked the nearest star to where I was pointing - Mizar as it turned out - and set about aligning the 9x50 RACI and Telrad.   The 9x50 in particular required some fairly radical adjustment from the Mak so I think at some point they'll each need a dedicated finder, will hang fire though until I've worked out if I want a RACI or straight through. It is immediately challenging to have a different orientation in the finder than the eyepiece but I was gradually getting used to the brain-gymnastics by the end of the night (the alternative being the physical gymnastics required by a straight-through). 

So, finders aligned, the moment of truth....   Transparency and seeing both looking good, temperature dropping rapidly though! 

The first thing I noticed was how bright Mizar and its companion looked, clear separation and stunningly brilliant with, to me at least, attractive spikes from the spider.  The second thing I noted was that I am clearly not a natural collimation expert - not a disaster but slight sea-gulling of brighter stars and couldn't quite achieve a pin-sharp focus. The field is also not in focus right across - acceptable though with best focus available across I'd say 70% of the field. I imagine this the Coma of which I have read so much.

Collimation tools duly ordered from FLO and I'll spend a happy afternoon tinkering and see what I can improve, reserve judgement on the focus generally until I'm confident all is aligned correctly.  While we're on the downsides, the Dob requires a different approach to observing - first of all my usual shielded-from-local LP corner of the garden with the Mak or a refractor on a nice tall tripod yields up an awful lot of car and garden wall with the lower positioned Dob.   Big shifts in position mean moving the chair around and in some cases that meant also dragging the scope around the yard a bit.   (There is a solution brewing which involves wheels, a drum stool and a drive out to my site with nice flat access and wide views with low sightlines). I swung to star test on Capella - very bright, slightly off round circles, more to do there...

With those caveats out of the way the light grasp on this thing is awesome!     The Auriga Messiers leapt out with many, many more individual stars and unresolved glow than I've yet seen. I always love M38, the Starfish but here the "limbs" floated on a sea of jewels.   M37, in the Mak the least impressive of the three, was transformed and I spent ages gawping at it, so many stars. 

Time for a galaxy, M81 & 82 I've got quite practiced at dropping onto in manual mode and sure enough there was the smudge in the finder and the pair bright in the field of the Baader Hyperion 24mm.  Noticeable that the visible extent of the galaxies is greater than in the Mak, unsurprisingly, spiral form in M81 stood direct vision and with AV a dust bar could be seen in M82.  Its not that I have NOT seen these in the almost 5 inch Mak but it is much more apparent here. I racked up the magnification from the  52x delivered by the 24mm Hyperion, finding yet another use for the Baader Classic Orthos, lovely view of each galaxy individually in the 10mm at 125x. Another difference from my smaller scopes, you can deploy some useful magnification on the fainter targets. 

Encouraged, I went for the Leo Trio -  partly because again I know exactly where to put the Telrad for that one - and pop, there were M65 & M66, pale ovals but not difficult to see. Trying to recall but I don't think I have ever seen them from the back garden before! Didn’t pick up NGC 3628 but then it’s like Blackpool illuminations round my way! 

The 'scope was covered in ice by now and looking down I noticed that so was I..... came in for a warm. 

Went back out around midnight and looked at M3 - again that seeing deeper very apparent, in the five inch this one is more of a misty ball, with the 10" I was getting the 
diamond dust" effect in AV.   M13 was stunning and was able to fill the field with it, many individual stars resolved and wide sparkling extent.   Looked at these two for a long time enjoying M13s tendrils and sparkle.   Looked half heartedly for M57 but either the cold or the finder confusion got the better of me and I elected to end on that super view of M13. 

Verdict - its a very different observing experience and another set of skills to learn. Sessions will probably involve longer views of fewer targets per session and I can certainly see nights where I won't want to get this out, however I was thrilled with the views! 

 

 

 

 

 

 

 

 

 

 

 

 

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Edited by SuburbanMak
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Welcome to the world of dobs! A world of both delights and frustrations.....😆

I believe your scope is f/4.8? You might find that some of the coma you experienced is down to the Hyperion - they are said not to do too well in scopes faster than f/6. A Morpheus, though.....👍

Combining the wide dob FOV with a wide-field eyepiece or two can be very rewarding. The 2" StellaLyra 80°, the afore-mentioned Morpheus, an 82° ES, all will give you superb views. 

I think you'll be very happy with your dob....just get down to the gym and do some weights!

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3 minutes ago, cajen2 said:

Welcome to the world of dobs! A world of both delights and frustrations.....😆

I believe your scope is f/4.8? You might find that some of the coma you experienced is down to the Hyperion - they are said not to do too well in scopes faster than f/6. A Morpheus, though.....👍

Combining the wide dob FOV with a wide-field eyepiece or two can be very rewarding. The 2" StellaLyra 80°, the afore-mentioned Morpheus, an 82° ES, all will give you superb views. 

I think you'll be very happy with your dob....just get down to the gym and do some weights!

Thank you & you may be on to something, although the fields were narrower, the BCOs looked much flatter.  I’ll put another eyepiece on my wishlist…

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Nice to read you first light report, always enjoyable to read of others pleasure.
10 is a great size, its the Dob I own and love when I do use it, but it always plast second fiddle to my 4" refractor when at home.
But at a darker location, well the 10" will be taken, but perhaps for not much longer as I have a car issue that may require replacement,
and that would be a much smaller town car, not sure a 10" solid tube would fit....where's my hacksaw?
Seriously, so pleased you enjoyed its use.

Your coment on being lower down and finding things get in the way has a familiar tune for home viewing,
but get out to a clearer horizon and boy does the extra aperture wow you.

Edited by Alan White
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Yes, the BCOs, being orthos, should suit that scope well if you don't mind the eye relief. The FOV is also very narrow, which you might find irritates you because of the constant nudging you need to stay on target.

3 minutes ago, SuburbanMak said:

Thank you & you may be on to something, although the fields were narrower, the BCOs looked much flatter.  I’ll put another eyepiece on my wishlist…

 

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4 minutes ago, SuburbanMak said:

Thank you & you may be on to something, although the fields were narrower, the BCOs looked much flatter.  I’ll put another eyepiece on my wishlist…

Just the one? 😉😛

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3 minutes ago, Alan White said:

Nice to read you first light report, always enjoyable to read of others pleasure.
10 is a great size, its the Dob I own and love when I do use it, but it always plast second fiddle to my 4" refractor when at home.
But at a darker location, well the 10" will be taken, but perhaps for not much longer as I have a car issue that may require replacement,
and that would be a much smaller town car, not sure a 10" solid tube would fit....where's my hacksaw?
Seriously, so pleased you enjoyed its use.

Your coment on being lower down and finding things get in the way has a familiar tune for home viewing,
but get out to a clearer horizon and boy does the extra aperture wow you.

It's actually the same tube length as my 8" StellaLyra, so it should go on the back seat of most cars. Just make sure you get a four-door! 👍

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1 minute ago, cajen2 said:

It's actually the same tube length as my 8" StellaLyra, so it should go on the back seat of most cars. Just make sure you get a four-door! 👍

I will downsize from a smallish Skoda Fabia, where it indeed does this to smaller still.
So it may not quite fit, tape measure when we go to the dealers for sure.

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A couple things that may be of interest.  They do make lifting straps that go around the OTA for easier handling.  I have thought about but not pulled the trigger just yet.  Secondly, I can highly recommend the GSO coma corrector.  It will clear up the edges of the image very nicely and it is affordable.  Lastly ...a good variable powered eyepeice and a variable polarized filter.

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Awesome report! I actually prefer spending longer on targets anyway. If something is looking good, at its best or close to, I can spend an hour just observing that one thing. Often you’ll see more as your eyes adjust to what you are looking at. 

I got this wooden adjustable stool for £10 via Gumtree from a guy in Southampton. Works a charm. I also drilled some holes (what can go wrong?) in the OTA and attached a handle. It’s the best mod I’ve done and wouldn’t be without it - no more slippery “fish”.

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Excellent purchase and fantastic first light with the new toy! I think the 10" will deliver some amazing DSO views. Looking forward to more of your reports with it.

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Congratulations and the cap is great for checking your primary alignment. For the secondary, I would recommend a Cheshire eyepiece and sight tube combination tool.

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Congratulations on purchasing your new scope! My telescope is a 10 inch dob as well, love it to bits, perfect combination of aperture and portability. I look forward to reading more of your astro adventures with your new scope 👍

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I started observing in the early 90's, and I've tried a lot of scopes, but for me there's no amateur astronomical instrument to beat a 10" mirror reflector on a dobsonian mount, if you're into simple observing. It's portable, it's easy to set up, and it gathers light like a demon.
I can stick it in the back of my van, drive out to the countryside, and set up in five minutes or less. Like you, SuburbanMak, I have a Telrad mounted next to a finderscope, and it works a treat.
I sense from your post that you may be thinking you've bought something a little too cumbersome, but stick with it bud. Dobs are amazing, and are easily the most fun I've had with any telescope. I plan to take it to the Elan Valley in Wales this summer.
These photos were taken last weekend...

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Edited by Swithin StCleeve
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Posted (edited)

@Swithin StCleeve thanks for posting the photos. Like the look of the dark sky camp set up complete with real ale, very civilised!   
Still getting to grips with collimation (getting there I think) but was out again last night and some of the views were staggering - caught the straight wall on the Moon just before it slipped below the rooftops and the detail on the lunar disc was incredible.  Globulars are just superb and had the best M57 view yet last night.

Had bought some big lockable castors but on reflection (no pun intended) reckon these will make it to tall and the ride be too jiggly so plan to take them back and exchange for a parcel truck and a couple of bungees - then it’ll be off to my darker site to put it through its paces next new moon ;) 

Edited by SuburbanMak
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