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The beast lives….


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I bought this quite some months ago, before we moved house, and it has sat unused in storage ever since. I had the day off today, and after some delightful jobs such as clearing the garage and costing the tip, I had enough space to try to assemble the scope and see how it looks. Please do excuse the mess in my garage, it’s still a work in progress!!

It’s a 16” f4.2 truss dob, home built by a competent craftsman roughly along Obsession lines. I don’t know the spec of the mirror, and am sure there will be some elements that can be improved, but hopefully it will give some decent low and mid power deep sky views and I acquired for what I thought was a decent price.

The movement in both axes is very smooth, with little stiction but it stays where you put it. The truss is nice and rigid too, and there is a good shroud which I will fit when I use it in anger. The secondary seems oversized to me, but I’ll see how it performs before deciding to make any changes. I do have an EQ platform I can put it on too if I feel it’s necessary.

One nice aspect is that the mirror box is actually quite light, and there are a series of weights which attach to the bottom of it to ensure it balances correctly. That makes it easier to move around.

I’m looking forward to giving it a go in my now darker skies, and even taking it south to the coast where there is a better horizon and even darker skies.

 

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96E3CB27-AC3E-49FD-B9D0-96F38C39691A.jpeg

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Looks like it's built to a very good standard, should give some lovely views. Decent focuser too. Are the mirrors in good condition or is a re-coating on the cards?

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44 minutes ago, RobertI said:

Looks like it's built to a very good standard, should give some lovely views. Decent focuser too. Are the mirrors in good condition or is a re-coating on the cards?

Thanks Robert. Yes, it looks good, focuser is an old Moonlite but in good shape and works smoothly. Mirrors could do with a clean but I don’t think they need recoating yet.

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44 minutes ago, R26 oldtimer said:

That's a really nice monster you have, hiding in your basement!

Thank you 🤣🤣

I shall unleash the beast sometime soon! 😱🤣

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I’ve just tried to collimate it for the first time. The main problem I’m having is centring the secondary left to right in the focuser. I’m using a concenter which helps, but because it is a three vane spider there is no simple way of moving the secondary in that direction. The secondary is oversized though so it may work ok for the moment, provided it is round in the focuser. It has collimated ok otherwise so I’ll just have to see how it looks in the eyepiece.

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2 hours ago, Stu said:

I bought this quite some months ago, before we moved house, and it has sat unused in storage ever since. I had the day off today, and after some delightful jobs such as clearing the garage and costing the tip, I had enough space to try to assemble the scope and see how it looks. Please do excuse the mess in my garage, it’s still a work in progress!!

It’s a 16” f4.2 truss dob, home built by a competent craftsman roughly along Obsession lines. I don’t know the spec of the mirror, and am sure there will be some elements that can be improved, but hopefully it will give some decent low and mid power deep sky views and I acquired for what I thought was a decent price.

The movement in both axes is very smooth, with little stiction but it stays where you put it. The truss is nice and rigid too, and there is a good shroud which I will fit when I use it in anger. The secondary seems oversized to me, but I’ll see how it performs before deciding to make any changes. I do have an EQ platform I can put it on too if I feel it’s necessary.

One nice aspect is that the mirror box is actually quite light, and there are a series of weights which attach to the bottom of it to ensure it balances correctly. That makes it easier to move around.

I’m looking forward to giving it a go in my now darker skies, and even taking it south to the coast where there is a better horizon and even darker skies.

 

207B860F-8625-453F-A865-9C37BCD2559D.jpeg

96E3CB27-AC3E-49FD-B9D0-96F38C39691A.jpeg

Had a 16 dob once, they are beasts. Was the mirror made by the same person who made the scope ? 

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40 minutes ago, Zermelo said:

Nice one Stu, that should make a dent in Bortle 4 skies.
Any further beasts still to be unearthed, or will that the biggest?

This is as big as it will get. My limit for manageability, I just wouldn’t use anything bigger. I have a 12” truss dob in storage which I will try to optimise for higher powers at some point, but this is my aperture limit! Will show plenty 👍

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1 hour ago, andrew s said:

Just don't damage your L2 moving it. Regards Andrew 

L3,4 and 5 disks are all shot already so hopefully I won’t do any more damage! The mirror box is comparatively  light so should be ok. Will look into building a trolley for it too. 

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24 minutes ago, neil phillips said:

Had a 16 dob once, they are beasts. Was the mirror made by the same person who made the scope ? 

Yes, I’ve had a couple of 16” Sumerians, a Canopus and an Alkaid. This is somewhere between the two in terms of portability but is much more rigid.

I don’t believe the guy ground the mirror but he knew his stuff so hopefully it won’t be a lemon 🤞.

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