Aldi telescope

[Ken31]

Right then, review part 1 (physical).
 
Here's what comes in the box:
 

• The "instrument" itself, a small Newtonian on a single-armed fork alt-az mount (I refuse to call it a Dobsonian);
• Caps for the front of the tube and the eyepiece aperture;
• 20mm eyepiece plus case;
• 4mm eyepiece plus case;
• Moon filter;
• 2x Barlow plus caps;
• Small planisphere (oh the irony);
• Stellarium CD.

I have disregarded some very poor wall charts and miscellanous documentation, all of which adds up to "let's package up as much as possible so that the kid opening this on Christmas day is gratified by all the bits".
 
Stellarium is of course free to download.  I have been known to buy things because of the software that came with them - I bought a graphics tablet I didn't need because it was a very cheap way to get hold of CorelDraw Essentials.  The planisphere is too small to be of any use at all, the irony being that I got a full size Philips free with the Sunday Telegraph last week.
 
The tube is 12½" long by 3¾" diameter.  It came with warning stickers on the tube and preventing access to the eyepiece holder with pictograms: "do not point at the Sun".  The first thing to note is that the tube does not rotate, so it may be awkward to look into the eyepiece in some orientations.
 
The mount is a swivel base with a compass built in and an azimuth scale, with a vertical arm to the altitude bearing with a clamp knob and an altitude scale.  Functional.
 
Optics and Collimation
 
The diagonal is supported on a threaded rod extending from one side of the tube (actually, it is the extension of one of the bolts that hold the focus assembly to the tube).  Clearly it has facility to adjust the collimation of the diagonal.
 

 
I didn't fancy fiddling with that bit, but I thought it would be safe to remove the mirror cell and have a look at that end (marked carefully to ensure it went back exactly as removed).  There are three screws holding a bezel around the mirror, but no idea whether they affect the collimation.  I did not go further to inspect the rear of the mirror.  The mirror cell is all plastic of course, and the mirror could be a shaving mirror for all I know (but appears to be silvered on the front face).
 

 
The clear aperture of the mirror was measured as 75mm.  While the mirror cell was out, I took a photo of the view from the bottom of the tube, which gives an idea how much obscuration there is.  Note the view out of the eyepiece holder via the diagonal.
 

 
Here is a view into the open end of the tube.  Note that the reflection of the camera lens, the obstruction of the diagonal, and the light from the eyepiece holder are in pretty good alignment.
 

 
This situation is not so rosy at the other end!  Here is a view into the eyepiece holder, as close as I could get to on the axis of the eyepiece tube:
 

 
Clearly the diagonal is not centred on the optical axis for the eyepieces, by about 7mm!  I moved the camera off-axis to get the outline of the diagonal coincident with the reflection of the diagonal in the primary mirror, and you can see how far off it is:
 

 
This needs correction badly if the telescope is going to perform anywhere near at its best, but the construction of the diagonal holder does not appear capable of adjustment to that extent.  I will try it on the sky without adjustment first, but then I will dismantle it and see what I can do.

[knobby]

Looks like a fun project... It might have been better if it was already in bits in the box :-)

[Ken31]

Guess what: point it at zenith and it makes a rain gauge.

[Naemeth]

At least the focuser looks more solid than the one for the Heritage (i.e. it's directly on the OTA )

Thanks for posting .

[Tiny Small]

Whilst I'm surprised anyone actually bought one, I am enjoying this. To for comparison, I own one of these http://www.tesco.com/direct/celestron-travel-scope-70mm-portable-telescope/213-2827.prd?recommendationId=79db0ace-cb4e-4d1a-8206-bceb2aaf2921.0&skuId=213-2827 and although small, it really is pretty good, and for the price... you really can't beat it.

[Ken31]

Yes, that would be much better at these kind of apertures, and as a Celestron that can't be too bad.

[GuillermoBarrancos]

I ordered the Heritage 78 from Skywatcher last week for my son

Gonna be interesting to see the quality of this thing.

[Ken31]

Guess what: point it at zenith and it makes a rain gauge.

...and horizontally it works well as an anemometer.

[Ken31]

The rain gauge is now dribbling out of the overflow pipe.

[smiler2]

If only it had a handle on the side it would make a nice large coffee cup to keep you warm on a nice clear night .

[Ken31]

Missed a chance for first light last night, I was busy.

[happy-kat]

Be interesting to see what it turns out like when you get first light

[Ken31]

Well now. I pointed it at Jupiter this evening. The view reminded me of my schoolboy mucking around with second-hand lenses and cardboard tubes.

To be fair, with the 20mm eyepiece the four Gallilean moons were easily visible, but the disc was difficult to achieve an adequate focus with all the chromatic aberration and coma (presumably from the off-axis diagonal). With the 4mm eyepiece I could just convince myself of the bands, but everything was very blurry.

I will now adjust the optics and see if it gets any better.

It occurs to me that Aldi had these because of the secondary mirror fault - rather than write off the production batch, flog them through the discount stores.

[Hertford Stargazer]

Playing around with my wifes Skywatcher Heritage 76 I had similar results, collimation was spot on and I could achieve focus on the moon but I was left with a horrendous blur to one side of the image (correct technical term beyond my limited experience) . Jupiter was the same although I noted the moons were fairly clear and crisp, instinctively I cupped my hand around the end of the tube, like a human dew shield, and to my surprise the image was near perfect. I will get round to making a shield out of cardboard just out of interest, although my wife seems unconcerned about it's optical performance because she says "it still looks cute" when sitting atop our dresser     

[Ken31]

If you want ornamental (but also functional) you should get one of the original 3.5" Questars.

[Hertford Stargazer]

I wasn't worried on either front to be honest, I think it's my wifes way of not feeling left out. I do have a little fondness towards it though, but only because it makes my scopes look bigger

The 3.5" Questars does look very nice but any available funds are currently reserved for a 12" dobsonian.

[Ken31]

You realise I was pulling your leg (I can't see how to add emoticons - that might have something to do with using an iPad)!

[Hertford Stargazer]

I did wonder when I done a google picture search but I didnt want to be rude lol.

[tekkydave]

Aldi is going to be selling a 76mm dob in next Thursday special buy. Anyone want to risk it and tell us what they are like. They are about £10 cheaper than SW and Celestron's 76mm mini dob. Being a dob, it will probably be better than most department store/supermarket scopes.

http://www.aldi.co.uk/uk/html/offers/special_buys3_28104.htm

I quite fancy the sticky toffee pudding actually.

[Ken31]

I did wonder when I done a google picture search but I didnt want to be rude lol.

The Questar is pretty enough, but it cost an arm and a leg at the time.

[Hertford Stargazer]

I think I'll stick with me 200p dob for the moment . I am looking at getting a 12" reflector but can't decide between another dob or the SW Explorer 300P-DS NEQ6 PRO 

[Ken31]

No, still not got around to "fixing" the Aldi. I was in the RSPB centre today, and they had something very similar on sale for £70 - just RSPB branding and including what looked like a nice beginners astronomy book. I had a look down the eyepiece holder and guess what - off-centre diagonal (though not so bad).

[AndrewBay]

Hi,  I am new to this forum after purchasing a National Geographic Dobson telescope for my daughter who is studying Astronomy for her GCSE.  So it was an impluse buy.  Aldi are selling it for £40 which is cheaper than Amazon, but have I made a booboo.  Knowing nothing about telescopes should I take it back and get something else for her?  If so what would you recommend as a first telescope which does not cost the earth?  Thanks

[happy-kat]

Hi :-)

I scrubed what I wrote as realised what you put.

If you were to stretch to £89 you could get a heritage 100p very similar easy to use mount but a known mirror quality.

I have not personally used the aldi scope to coment on it's real usability/quality of view.

[happy-kat]

Sorry a link to see the one I mentioned

http://www.firstlightoptics.com/beginner-telescopes/skywatcher-heritage-100p-tabletop-dobsonian.html