8 inch Dob Finished at Last

[Beulah]

That's such a beautifully made scope, well done! Didn't know you could buy flexible plywood. I like the way the finderscope is underneath the eyepiece. Must make that modification myself.  

[steppenwolf]

An absolutely gorgeous telescope - well done!

[Dave Lloyd]

Super looking beast. Good build description too.

[Paladin]

Hello all

In my last post, I listed various mods to be carried out before a proper first light, and although most of them have now been done, the rotten weather has prevented any visual testing.  The elderly mirror has now been cleaned, and although it looks a lot better than it was, I’m slightly disappointed with it, and it really ought to be re-aluminized, but that will have to wait for now.  Anyway, as Basil Fawlty says "it’s not in absolutely mint condition, but it could certainly be used in an emergency". 

To cut down on reflections I have flocked the inside of the focuser, and have also added more flocking to the inside of the OTA, but I shall judge any improvement before considering any more work in this area.

The guide for the altitude bearing has been replaced with an adjustable friction brake made from 2 aluminium strips covered with felt & 2 screws with threaded sleeves which were previously used to fasten kitchen cabinets together.  This appears to be a vast improvement on the original, as the tube now stays wherever it is put.

After reading Astro Baby’s useful tutorial on collimation on her website, I decided to adjust the diagonal before fitting the main mirror, and found this a lot more straightforward, as it cuts down on the number of reflections to take into account. However, when I did fit the mirror, I had a terrible job trying to collimate it, so I had to take it out again to find the reason.  I had originally held the mirror in place with felt pads pressing against the rim with minimal pressure, which obviously was not enough as the mirror was moving about preventing alignment; so I fixed it in with silicon mastic to make a semi-permanent fit.  I refitted the mirror to the tube, and screwed the adjustment knobs right in, and to my delight, found that the collimation was almost spot-on; only a slight tweak being required to get it perfect.

So, it’s all down to an improvement in the weather; hopefully we’ll get some clear skies before long.

Best Wishes: Paul

 

[Paladin]

First light at Last!

Clear skies tonight meant that I finally managed to use the scope in earnest, but only on the moon.  I was quite pleased with the result although there is still work to do on the mount because there is still too much ”stiction” on the altitude bearings.  I think it is only a matter of experimenting with various polishes to find one which will give the right amount of friction.  I am open to suggestions if anyone has had the same problem.  Ideally, the amount of effort needed to move the scope should be the same for both the altitude and azimuth bearings.

Because of the jerky movement, I could use only low-powered eyepieces, namely 32 & 20mm Revelation Plössls and a 25mm Circle T Orthoscopic.  The views were most impressive and if my memory serves me right, were better than in my previous scope, a Celestron NexStar 6 SE.

I couldn’t resist holding up a Lumix DMC-TZ35 compact digital camera up to the eyepiece and clicking away.  I’m so pleased with the results that I am very tempted to see how far I can with different settings.  I shall probably be a frequent visitor to SGL Imaging forums now, as I am a novice in this field.

Here are 3 of the better images: see what you think.

Best wishes: Paul

 

[mapstar]

They look great Paul.

I'm still trying to source some formica that is suitable for my scope as the last I used created just that bit too much station especially on az.

I'm sure looking at the formica you have used its as you say just a matter of the correct polish.

Damian

[Charic]

Update

  I can assure you that my craftsmanship is not as good as some of you have suggested, as there are many things which I wish I had done better.  However, as the first pics were received so well, here are a few more.

The camera never lies? Take you right hand, place it over your left shoulder, then pat smartly, well done. 

Now when you sell this one, the original,  the one and only, with a  Paladin price tag to match?  don't take so long to build the next, and if the feedback is positive, I'm sure you could survive from the income?

[Vox45]

It is a piece of art ! I like the fact that you kept the wood aspect of it, not the cold metallic look of all scopes out there

[jdg600]

That sir, is a thing of beauty!

[Merlin]

Ditto. It will be interesting to see how the material stands up to our humid climate.

[Paladin]

Thank you all for your kind comments.

Merlin: "It will be interesting to see how the material stands up to our humid climate".

All wooden parts received 2 coats of Cuprinol wood Preserver before 3 or more coats of marine varnish, so it should survive the British weather.  Although the intention is to eventually keep the scope in the garden shed, at the moment it resides in the living room, where my wife is treating it like a piece of furniture.  Luckily it has escaped the Christmas tinsel treatment so far!

Best wishes: Paul

[JamesM]

I've come a little late to this appreciation society but wanted to extend my congratulations to you Paul on building a terrific scope. The wood grain to me is reminiscent of the cloud formations that can be seen on Jupiter. Perhaps if you were to make another one (....you know you want to ) you might like to consider using some Tasmanian Beech for a strategically placed red spot!

Great work but at the end of the day, the real beauty of telescopes is in what they can reveal through the eyepiece - though your scope does have the hidden advantage of presenting a good view even when the clouds are in.   

Clear skies.