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The other week I happened to be surfing through ebay, just seeing if anything interesting cropped up.

Well, it did. A Swift 831 77mm f1000mm OTA complete with erect-image converter and an original 12mm Kelner. The pictures looked good, so I sent a couple of questions to the seller. The item was listed in the UK and the price was reasonable. I didn't get much info back, but looking closely at the pics, I decided to go for it. It "looked" good, including the pictures of the optics. I paid and waited.

It arrived a few days ago. THe condition matched the pictures, and I was impressed by the condition it was in! Considering that this could be from 1968, the tube has only a very few small marks, the optics just some minor dust, and the focuser....well, the focuser was gummed up pretty tight, but worked. I had ordered a 36.4mm to 1.25" adapter to fit on the drawtube, so I can use 1.25" accessories, and some 76mm rings, so was able to set it up on my AZ4 for a quick look before going to work.

Nice and sharp with a 20mm TV Plossl, and apparently colour-free. Focuser was unreasonably stiff, but otherwise very pleased!

In the days since I've tried to do some work to the focuser, but it is on the tube so tightly I wonder if I'll ever be able to unscrew it. I suppose I may have to resort to WD40 or something, but really want to avoid chemicals if possible. The focuser definitely needs to come off as the adjustments I made to it in-situ have actually made it loose and sloppy now, so....yeah... that's a little project!

I've been lucky enough to source an original finder for it through one of the regulars on the CloudyNights Classics forum in the USA so hope to get that here in the next few weeks. Hopefully then the focuser will be sorted and it will be looking more complete.

So this is the big brother to my 60mm Swift 839, and sits between it and my Tak FC100-Df. Now depending on what you read, it is possible that all three of these scopes have Takahashi DNA in them, so I'm pretty happy. I hope to have the 831 as a working, regularly used scope and look forward to lunar, double-star and planetary viewing with it. 

(Assuming I can get that d%£m focuser off... lol!

 

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Focuser3.jpg

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wow, im probably one of the few on here that appreciate just what you have got there, great find, i was only looking for one on ebay just the other day, several years ago i missed out on one at a good price, really hope you get the focuser working sweet, update us on how good it is 

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If you have a soldering iron, holding that against the screw head for a couple of seconds can help to remove stubborn screws. If the screws go into plastic, then it would probably be prudent to try something else.

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21 minutes ago, Stargazer33 said:

If you have a soldering iron, holding that against the screw head for a couple of seconds can help to remove stubborn screws. If the screws go into plastic, then it would probably be prudent to try something else.

The focuser screws directly onto the end of the OTA. It probably hasn't been unscrewed in several decades, so is understandable that it's hard to shift. 

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30 minutes ago, nightfisher said:

Ant can you dismantle the focuser in situ and service it leaving just the focuser body on the tube

Only partially, but not enough to make any real difference. In fact, I tried that and it led to some more problems that I really now need to get it off to fix. I know it does unscrew - I've seen pictures of the focuser dismantled, and my 839 has a similar arrangement.

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On 17/08/2019 at 18:38, A McEwan said:

The focuser screws directly onto the end of the OTA. It probably hasn't been unscrewed in several decades, so is understandable that it's hard to shift. 

In that case, can you put a heater tape around the collar of the focuser and turn it up to '11' 😁 to warm and hopefully expand that in order to unscrew it? A pair of those bright orange rubber freezer gloves might help with the grip too.

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1 hour ago, Stargazer33 said:

In that case, can you put a heater tape around the collar of the focuser and turn it up to '11' 😁 to warm and hopefully expand that in order to unscrew it? A pair of those bright orange rubber freezer gloves might help with the grip too.

Yes, I have a dew band I can do that with. Meant to give it more time today but have had other things to do, so hopefully one evening this week.

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It will be interesting to hear how this scope genuinely performs, i did hear kinda mixed reviews on this, some say superb some say not as good as its little brother

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  • 2 weeks later...

Another small update. I got a card through the door today, inviting me to visit the local Post Office and pay them some money so that I could get a parcel to open. After doing so, I made myself a cuppa, cleared a space, and opened up this box - all the way from the US of A, and a gentleman over there who is very active on the Classic Telescopes section of Cloudynights, Dave Trott.

Inside the package, an original 40mm finderscope for the Swift 831! Complete with the adjustment mechanism, and home-fabricated attachment brackets. I'll need to finish those off - paint, line with felt, select a suitable bolt to hold it all together.

Getting excited now about getting this project near ready for the coming season. Not that it needs much work, really. I've been really lucky to find this scope - and the finder - in such good original condition. 

As an aside, my brother, who is more familiar with binoculars and prisms etc, is dismantling and cleaning the correct-image converter for me, as although it works well, it needed a really good clean.

Ant  :) 

finder (1).jpg

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Focuser update! After a couple of hours work (- honestly, thought I'd NEVER get some of those tiny screws undone -) this is what I'm left with. Oh yeah 😁 - this is what I was aiming for! Can't wait now for a proper astronomical first light. If you haven't seen one of these older focusers before, there is an inner drawtube, which slides in and out, and is fixed by a compression locking collar. This is used to achieve "rough focus" and then the actual rack & pinion focuser is used to achieve fine focus. 

:)

 

 

Edited by A McEwan
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Well, I got a very quick half hour First Light session. The scope cooled outside for half an hour first, and first target was Mizar & Alcor. Beautiful sharp stars at 50x with no hint of false colour. Increasing to 100x showed similarly sharp views. I then switched to Polaris. The companion B was easily seen. There was some turbulence so I can't be 100% sure that my short session can really confirm anything yet, but I feel there is some astigmatism. I'm assuming that is what I detected, as outside of focus the rings seemed slightly oval horizontally, and inside focus slightly oval vertically...

But I really need a longer session. Pleased overall, and at low to medium power the two objects I viewed were very presentable! At least I know "it works"!

:)  

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  • 5 months later...

Late to the party here, but I have an 831 as well. Long story, but it has taken some stunning images of the moon - amongst the clearest I have taken. I’m desperate to find a finder for it though.....

They are amazing scopes.

Keith

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  • 5 months later...

My 831 project is almost finished now.

I had the optic looked at by Es Reid, who was very encouraging about it and described it as "sweet"! He cleaned it up and I got it back from him yesterday. In the meantime I had been working on the fixing hardware for the 40mm original finder-scope which I got from the USA last year.  (I actually couldn't believe how long I'd been sitting on this not doing anything with it - so I'm glad to have finally "got round to it"!)

The brackets were prepped, primed and sprayed with Rustoleum paint to give the wrinkled finish to match the other metal hardware on the finder, and I also applied black flocking material to in the inside of the dew-shield. The lens cell and dew shield parts all screw into each other, which is good in that everything is held in perfect alignment, but also tricky, as I can by trying to unscrew the dew shield, and suddenly the cell starts unscrewing! So it takes some care. The dew-shield actually extends on this scope, but only by an inch or so. It's nice, but I will be using an additional flexi dew-shield over the top to extend it a bit.

Anyway, it's all together again now and ready to go - except I need to find a suitable bolt to finish off the finder-scope mounting! All those boxes of bits'n'bobs and I don;t have the right style bolt. Unbelievable...  🤨  I'm not particularly a big fan of straight-through optical finders anyway, but it will be nice to have it on there for "completeness".

That's pretty much it. Just need some decent skies now. It will go on my AZ4 or GP mounts no problem, and I'm looking forward to actually gathering photons with this wonderful instrument!  :D 

refurb4.jpg

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  • 3 months later...

Final update. Finder-scope mounted, and observed Mars the other night at 259x, which showed a lovely sharp, clear image. (Seeing co-operated wonderfully, mind!)

Essentially, this scope is now "finished". I just need some caps for the finder, and a suitable case that will hold the scope with finder attached, as it's a faff to put on and take off every time I use it.

Pictures are fairly terrible - poor lighting, but best I could do, I'm afraid! ;) 

Ant  :) 

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