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Dobsonians - Little & Large

Posted: Sun Dec 09, 2012 1:46 pm
by rwilkinson
I'd never really tried a Dobsnonian-mounted reflector until using the BBT this week, and I must say that I was quite impressed. The sturdy "pan & tilt" base gets away from any problems with "whackery" tripods and mounts, and of course there's no polar alignment to do! Nor is there any need to rotate the tube to re-position the eyepiece, as with an equatorially-mounted Newtonian.

Following the recent thread on the table-top models from Celestron and Aldi, I spotted this mid-range model: ... xtube.html
It uses the same optics as Carl's old SkyWatcher 130P with which we did our Messier mini-marathon down at Kelling Heath a few years back , but in a rather more compact form. It's really easy to store and carry about, but I guess that the base needs to be stood on a small table in order to get the eyepiece up to a comfortable height? Or could you use it when seated next to it?

I wonder if any of our readers have tried this model? It looks like it could be quite a handy "grab & go" starter-scope.

Re: Dobsonians - Little & Large

Posted: Sun Dec 09, 2012 9:01 pm
by bbones
I have to agree with Ross the Dob is so easy to use once its setup of course and even the tiny Sharple Dob has been fun to use and there are some nights when I just want 1/2 an hour out it's been ideal in some ways even better than some small Binoculars all be it no where near as good as my other scopes

I'm looking at getting one, however there are 2 issues

1. The secondary mirror only has a single support, will this be solid enough?

2. The focus is achieved buy screwing the eyepiece in and out rather than the normal rack try focuser, will it be messy to focus?

If I get chance in the morning I'm going to pop over to the Stockport store to take a look as they have one in stock. If I manage to get over I will update this post

The other aspect is its very good to learn your way around the sky, even if it difficult at first

Re: Dobsonians - Little & Large

Posted: Fri Dec 14, 2012 5:14 pm
by rwilkinson
I see that Bill couldn't resist getting one of those retracting 130P Dobsonians:
mbt.jpg (205.76 KiB) Viewed 16003 times
as a present for his grand-daughter of course!

Re: Dobsonians - Little & Large

Posted: Sat Dec 15, 2012 10:45 am
by bbones
Thanks Ross

I was going to purchase one of the Heritage 76mm Mini Dobsonian but then saw the cheaper one in Aldi, then Ross pointed out that for a few more pounds I could get a Heritage 130P, Hmmm :o

The Heritage 130P uses the same Parabolic Primary Mirror as used in the highly-renowned Explorer 130P which has always had excellent reviews, so I thought it was worth a look :P

130mm primary mirror
Focal length 650mm (f/5)
10mm and 25mm (1.25) eyepieces
Highest Pratical Power (potential) x260
Red Dot Finder
Weight 6.2Kg

Some points worth noting

I had some concerns as the focus is achieved by rotating a large section of the eyepiece holder, in use I found this not to be an issue and is very solid.

The Single arm for the secondary mirror looks a bit unstable but I have not found it an issue, it might become a issue if I ever have to set the collomation.

The Collapsible / Extender Tube assembly is a bit stiff however once in position its very firm.


I have only had the importunity to use it once and was very impressed. Using the Red Dot Finder I was able to point the scope easily and the views where exceptional, even though the seeing was no good I was able to see the 4 moons of Jupiter and also make out the 2 darker rings.

I went to my reference double stars Mizar and Altor ( these I have used to compare all the scopes I have used) and the separation was clean and distinctive.


Great value for Money at £140, good primary mirror, very portable, easy to store, easy to use and ideal first scope, I'm sure my Grand-Daughter will enjoy it when she comes round ;)


Re: Dobsonians - Little & Large

Posted: Sat Jan 05, 2013 5:07 pm
by rwilkinson
I saw Bill's 130P Dobsonian yesterday, and it does indeed look like an ideal "grab & go" scope, or a beginner's starter-scope.
I was also impressed how compact it is when packed away.

And I noted that Bill is "looking after it" for his grand-daughter! ;)

Re: SkyWatcher 130P "heritage" Newtonian

Posted: Sat Oct 25, 2014 8:27 am
by rwilkinson
Having been impressed with the one which Billy Bones got "for his grand-daughter", I've just acquired one to use while I'm working down in the Wye Valley.
I like its compact sliding-tube design (it folds down to a squat cylinder about the size of a Meade ETX 125), and no-nonsense helical focusser.
Last night I mounted it on an old Celestron NexStar SLT head and tried it out from my back garden in Bolton.
SkyWatcher 130P on a NexStar SLT mount and my multi-function tripod
SW130p_NSXLT.jpg (148.21 KiB) Viewed 14419 times
I had a look at the double-stars Albireo, Almach, Mizar and Epsilon Lyrae, the Double Cluster and the Hercules globulars (M13 and M92), the Ring and Dumbell nebulae and the galaxies M31 & 32 and M81 & 82.

It's just a simple f/5 Newtonian, so I could see quite a bit of coma when using a 20mm eyepiece, but with the narrower field of a 10mm it was much better. And at just £45 for the optical tube plus £4 for a red-dot finder (all from AstroBoot) it's got to be the best-value 'scope I've bought. Now I'm looking forward to trying it out under some dark skies...

Re: flex-tube 130mm Newtonian

Posted: Sun Dec 21, 2014 1:54 pm
by rwilkinson
On Friday night I finally had the chance to try out the little 130P flex-tube reflector from a dark-sky site (in the Wye Valley).
I'd fitted it with a cheap & cheerful 25mm Plossl eyepiece and mounted it on a Celestron NexStar alt-az Go-To system. After performing an alignment on Aldebaran, I dialled up "M001" (the Crab Nebula); I've always found this object too faint to see in the eyepiece from Bolton, but with the contrast against the dark sky I could see it quite plainly through this little 'scope.
Then following another alignment on Dubhe, I had a look at the M81 & M82 galaxies in Ursa Major. I could fit them both in the field of the low-power eyepiece, and their different shapes could be seen easily.
The nearby trees prevented me from looking for M51, M57 & M27, and Andromeda was too high in the sky to point at with the NexStar mount (the lower half of the 'scope would have hit one of the tripod legs), so I couldn't look for the galaxies there.
But Orion was rising in the SE, so I pointed at M42 and could see the Trapezium and its surrounding nebulosity very clearly.

Finally, I wanted to try webcam imaging using this system. Now it's usually difficult to get any camera close enough to the focal-plane of a Newtonian, but the unique sliding-tube design of this 'scope allowed me to retract the head-unit slightly, thus shortening the optical tube and moving the focal-plane further out of the eyepiece-holder. Then by juggling this retraction and the helicoid focusser, I managed to focus an image of M42 onto the webcam's CCD. But with a 650mm focal length, the image-scale was too big to capture the whole nebula, and the imperfect tracking of the alt-az mount was causing trailing on exposures even as brief as 10 seconds. But after capturing more than seventy 10-sec images, I found that around half of these were steady enough to try stacking, and the "Global matching" stellar registration algorithim in IRIS made short work of the field-rotation:
M42 and the Trapezium, from 34x 10-sec using a modified Philips webcam at the prime focus of the 130P Newtonian
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Next time I'm going to try fitting a focal-reducer on the camera, to reduce the magnification and so increase the field-of view and reduce the exposure-times...

Re: Skywatcher 130P with focal reducer

Posted: Tue Apr 07, 2015 12:44 pm
by rwilkinson
Last night I finally got the opportunity to continue my experiment from just before Christmas: I was interested to see what sort of image I could get from the little 130P Newtonian and a long-exposure webcam, using the NexStar tracking alt-az mount.
My previous test on M42 suggested that I should try a focal reducer (to increase the field-of-view and reduce exposure times), so last night I had a go at Comet Lovejoy with a low-cost one (from Revelation Astro) fitted.
The cunning design of this 'scope's retractable tube allowed me to achieve focus by partially sliding in the support-struts (thus bringing the secondary and eyepiece-holder further down the tube), but this degraded the collimation, and especially with the focal-reducer fitted I could see a lot of coma on the brighter stars. But I didn't have time to adjust this, so I just started collecting images. I found that trailing was tolerable with exposure-times of 12-sec or less, so I wound up the camera's up gain well above its normal setting and took 45 exposures:
Comet Lovejoy on 6-Apr. 45x 12-sec using converted Philips webcam with focal reducer fitted to 130P on alt-az mount
lovejoy_6apr.png (114.36 KiB) Viewed 13506 times