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Swift 831 has arrived!

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31 replies to this topic

#1 Spyke

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Posted 15 August 2019 - 05:48 AM

Bought off ebay, this arrived today - expertly and fastidiously packaged, double wrapped in bubble-wrap, packed with cardboard protection panels, and then in a sturdy box! I tore into it to reveal a rather lovely looking OTA! Cosmetically the condition looks very good indeed. There are only very few slight marks on the tube, and I think some of them may be possible to remove. The lens cap is loose, so I've put in some felt tabs just to keep it in place for now.

 

I set it up on my AZ4 for a quick test before going to work, and found that the focuser is extremely tight. Like use both hands on the focus knobs tight! Looking at the drawtube, I can see and feel sticky hard residue. Looks like I'll need to strip it down and regrease it, like I did on the 839 years ago. I was surprised at the limited drawtube travel too, compared with the 839. The pictures in the gallery (linked) show it at full extension.

 

gallery_976_11701_15533.jpg

 

I was surprised by the unscrewing dew-shield - wasn't expecting that! Also very pleased by the condition of the optics. A few specks of dust here and there but no sign (yet) of anything nasty looking. 

 

The included image-corrector and 12mm Kelner are also in very nice condition! 

 

I only got a very brief view through the scope, using a Televue 20mm Plossl, looking at distant fields and closer flowers, and the view was bright and colour-free, though I didn't get a chance to observe critically. 

 

Pleased so far! Link to photo gallery. 

Ant :cool:


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#2 Defenderslideguitar

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Posted 15 August 2019 - 06:33 AM

congrats    Swift 831  a keeper for sure


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#3 Terra Nova

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Posted 15 August 2019 - 07:47 AM

Congratulations! You got yourself a keeper there!


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#4 Spyke

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Posted 15 August 2019 - 03:00 PM

Would I be right in assuming the focuser unscrews off the ota? Feels very tight if so.

 

I guess I'm missing the inner drawtube extension part? I suppose that explains the limited focuser travel I have as the extension would normally be adjusted to get close to focus, then fine-tuned with the focus knobs, yes?


Edited by Spyke, 15 August 2019 - 04:43 PM.


#5 Esso2112

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Posted 15 August 2019 - 05:20 PM

I guess I'm missing the inner drawtube extension part? I suppose that explains the limited focuser travel I have as the extension would normally be adjusted to get close to focus, then fine-tuned with the focus knobs, yes?

 

Based on the photos you posted in your gallery, I think you have the inner drawtube. When I got my 831, I actually thought the same thing. It was very stiff and hard to pull out, but since there is a visual back on the scope, the drawtube is there. Loosen the large silver ring and maybe get some degreaser in there. I was able to pull gently, but forcefully and got mine out without the use of any chemicals. Since your focuser is still due to hardened grease, I suspect this is impacting the inner drawtube as well.   


Edited by Esso2112, 15 August 2019 - 05:22 PM.

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#6 Spyke

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Posted 16 August 2019 - 06:34 AM

I guess I'm missing the inner drawtube extension part? I suppose that explains the limited focuser travel I have as the extension would normally be adjusted to get close to focus, then fine-tuned with the focus knobs, yes?

 

Based on the photos you posted in your gallery, I think you have the inner drawtube. When I got my 831, I actually thought the same thing. It was very stiff and hard to pull out, but since there is a visual back on the scope, the drawtube is there. Loosen the large silver ring and maybe get some degreaser in there. I was able to pull gently, but forcefully and got mine out without the use of any chemicals. Since your focuser is still due to hardened grease, I suspect this is impacting the inner drawtube as well.   

Thanks for this - it's a possibility. I'm going to have a proper look at it at the weekend and take it slowly.  :) 


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#7 roscoe

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Posted 16 August 2019 - 08:09 AM

Yes, the focuser unscrews from the tube.

You do have the tailpiece, because the adapter that allows you to use that 1.25 diagonal is screwed into it.  Perhaps the retaining ring is just quite tight.  It is a compression-ring system under that nut.  Normally, the scope would have had a visual back installed there that reduced the tailpiece to .965 for the stock diagonal/EP's.


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#8 Spyke

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Posted 16 August 2019 - 09:26 AM

Yes, the focuser unscrews from the tube.

You do have the tailpiece, because the adapter that allows you to use that 1.25 diagonal is screwed into it.  Perhaps the retaining ring is just quite tight.  It is a compression-ring system under that nut.  Normally, the scope would have had a visual back installed there that reduced the tailpiece to .965 for the stock diagonal/EP's.

Thanks. You are quite correct - the inside drawtube extension is there - it was just completely hidden! More surprises!  :) 


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#9 Spyke

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Posted 17 August 2019 - 10:01 AM

Only a very small update on the 831. I am still trying to get the focuser off, without resorting to chemicals or gripping devices if possible. To that end, I "give it a go" every time I pass by it. No luck yet, but I'm sure it'll come off sometime!

 

Also I have purchased a finder and bracket (thanks Dave!) for this scope, so I'm looking forward to that arriving in the next few weeks.

 

In the meantime, I'm just cleaning any gunk out of little out of the way places.

 

Ant :cool:


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#10 ccwemyss

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Posted 17 August 2019 - 09:21 PM

Just a thought -- point it vertically, and hang a weight from it between your attempts. Let gravity do some of the work.

 

Chip W. 


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#11 roscoe

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Posted 18 August 2019 - 09:36 AM

The cheap gardening/work gloves that are knitted fabric dipped in a rubber compound are great traction-aids for your hands in situations like this.

 

Also, you might try heating the tube with a hair-dryer (not a heat-gun, because you might cook the paint) to see if that works.  If you have a big-enough freezer, you might try putting the tube/focuser in it to chill it first, so you get maximum thermal expansion of the tube.... but take the objective and cell off first.


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#12 Spyke

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Posted 21 August 2019 - 02:44 PM

Well, with the help of my brother and a slightly worrying method, we eventually got this to happen. All is well. No stripped threads - it just seems to have been in-situ for a very long time. It now threads on and off easily, and I can get to work "fettling" the focuser when I get a free day.

 

After that's done, I can do some more cosmetic tidying, and even get some looks through this thing!   :)  

 

gallery_976_11701_44984.jpg

 

Ant :cool: 


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#13 Spyke

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Posted 31 August 2019 - 07:05 AM

In addition to tweaking the focuser, I have another little job to do. The finderscope and mounting hardware that I bought from Dave Trott arrived today, bringing with it several days worth of pouring rain! It is really nice, and I just need to paint the mounting brackets, line them with felt, and find a suitable bolt to secure the whole (I have loads of bolts)! Just need to get a solid few hours that I can dedicate to the work. Wish me luck!

 

gallery_976_11701_227405.jpg

 

Ant :cool:


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#14 Spyke

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Posted 31 August 2019 - 12:48 PM

Got a couple of hours to play with - I mean "work on" - the Swift, and finally got that focuser how I want it. Took a while - thought I'd never get some of those tiny screws undone, but managed to get there in the end. It is now very smooth, with no hint of slipping with any of my normal 1.25" eyepieces. There is a tiny tiny amount of backlash in the R&P, which is perfectly acceptable to me, and about the same as I ended up with on the 839 focuser too. Maybe I need to invest in a different grease? 

 

The outer drawtube really needed shimming, so I used very finely cut strips of thin shiny sticker sheet I had lying around. One layer on each of the guide sections within the focuser body gave it a much smoother, more even movement.

 

Anyway, I'm very happy with how this is now. I'm looking forward to getting a proper astronomical First Light, though with the rain forecast for the next few days, I think it'll probably be a while yet.

 

https://youtu.be/E4tiWF8bnVs

 

Ant :cool: 


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#15 Spyke

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Posted 01 September 2019 - 04:24 PM

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"!

 

Ant  :cool:


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#16 Spyke

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Posted 21 September 2019 - 03:34 PM

I think I have good news and bad news.

 

Suspecting astigmatism, I slightly loosened the lens retaining ring and had another test session tonight. The astigmatism was definitely reduced - but also definitely still there. So it's good that it's improved, but the bad news is that I assume I have to experiment with rotating the elements with regard to each other and see if that eliminates the problem?

 

If that's the case, that's going to take a lot of effort and time, which is unfortunate. 

 

There's also some flaring, which I suspect I can improve by improving the blackening inside the front of the tube assembly, and on the rear baffles, which seem particularly shiny.

 

As a matter of interest, how badly will astigmatism affect the quality of the view - I mean, how much does it detract from for example planetary detail, all other things being equal?

 

Ant



#17 Terra Nova

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Posted 21 September 2019 - 03:47 PM

Make sure there is no wedging of the objective going on in the cell. 


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#18 Chuck Hards

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Posted 21 September 2019 - 06:37 PM

Terra has an excellent point, the lens may not be seating properly in the cell.  

 

I have only ever heard of two Swift objectives that didn't perform as good as they should, and the root cause was never determined for either of those, if memory serves.  I think a mechanical issue on all of these is a possibility that should be thoroughly examined.  A Ronchigram would give a lot of information, as well.

 

Nice brackets for the finder, Dave got those reproductions from me.  I used them on my own 831 restoration, they are pretty precise copies of the originals.  

 

 

831 04 024.jpg

 

831 04 026.jpg

 

831 04 021.jpg

 

831 04 031.jpg

 

 

 


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#19 Spyke

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Posted 22 September 2019 - 02:25 PM

Terra has an excellent point, the lens may not be seating properly in the cell.  

 

I have only ever heard of two Swift objectives that didn't perform as good as they should, and the root cause was never determined for either of those, if memory serves.  I think a mechanical issue on all of these is a possibility that should be thoroughly examined.  A Ronchigram would give a lot of information, as well.

 

Nice brackets for the finder, Dave got those reproductions from me.  I used them on my own 831 restoration, they are pretty precise copies of the originals.  

 

 

attachicon.gif 831 04 024.jpg

 

attachicon.gif 831 04 026.jpg

 

attachicon.gif 831 04 021.jpg

 

attachicon.gif 831 04 031.jpg

Yes, the bracket is great. I will need to try to match the paint colour - any hints/tips greatly appreciated!

 

On slightly different tangent, I love the pictures of your 831. Very fine. I will probably never get an original mount for it, but hope someday to find a Polaris mount for it. In the meantime, AZ-4 or Vixen GP for me.

 

Ant  :cool:  



#20 Chuck Hards

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Posted 22 September 2019 - 02:37 PM

I actually have two 831 mounts at present, one is a very early model, the other later.   I need to do some cosmetic work to both of them, but the OTA rides fine on the old Edmund mount for now.  

 

I had the "Swift Brown" custom matched by an automotive paint shop.  I first clean and prime the steel brackets, then give them a coat of grey wrinkle.  When that is fully cured I overspray it with the Swift Brown.

 

There is a Rustoleum spray-can color that is close, I believe it is a textured paint so mimics the wrinkle somewhat.  I can't recall which color it was however.  Is Rustoleum spray-paint sold in Scotland?


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#21 rcwolpert

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Posted 23 September 2019 - 08:44 PM

It’s the Rustoleum Autumn Brown # 223523. Available on Amazon.


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#22 rcwolpert

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Posted 23 September 2019 - 08:59 PM

To remove the astigmatism from my Swift 831 I had to separate the lens, remove the 3 spacers, clean the two objective components really well, then carefully attach new spacers (don’t reuse the old ones), and carefully reassemble the objective. Newton’s rings should now be centered, concentric, and we’ll-spaced. 


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#23 rcwolpert

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Posted 23 September 2019 - 09:32 PM

DPAC of my Swift after astigmatism surgery.

 

gallery_211497_4490_266919.jpg


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#24 Spyke

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Posted 11 August 2020 - 08:12 AM

Am resurrecting this thread as I've been doing a fair bit to this scope over the last few weeks.

 

I started by contacting Es Reid about having him have a look at the lens, get his assessment, and see if he would make any necessary adjustments, and clean it up. He agreed, and I packed the cell off to him a couple of weeks ago. While it was away, I set about painting the finder-scope mounting brackets that Dave Trott had supplied to me, along with the finder a long while ago!

 

Sanded them down, primed with metal primer and then used Rustoleum Autumn Brown for the top coats, before coating with a clearcoat for protection. Found some nice felt for the linings, but I still have to find a suitable fixing bolt - ideally that looks the part as well as functioning. Amazingly, despite having several parts and bits boxes, I had nothing that fitted! Still.... nearly there!

 

Lens arrived back yesterday and looks beautiful! Es Reid described it as "sweet" so I'm very optimistic now for the views. Poor weather forecast for next few days though, so I may have to be patient....   :) 

 

med_gallery_976_11701_48171.jpg

 

med_gallery_976_11701_46272.jpg

 

sml_gallery_976_11701_251049.jpg  sml_gallery_976_11701_71690.jpg

 

Thanks to Dave Trott for the finder and mounting hardware. I couldn't believe I'd been sitting on this so long, but am glad to have made proper progress now and hope to get some views now it's starting to get darker at night here again.

 

Ant  :cool:


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#25 Spyke

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Posted 07 November 2020 - 04:54 PM

Just a little update on this scope, as I have now spent some time with it since it's "work" and have come to know (and love) it properly!

Tonight's views of Mars were some of the best I've ever had in any of my scopes. Not THE best but certainly top tier! 

 

The seeing was very good and I employed many of my Orthoscopics, from 18mm right up to... 3.9mm! Yep, 3.9mm, giving 256x, and the image was sharp, clear and detailed. Striations in the colour of the dark features and a hint of polar ice.

 

Also, I let the planet drift out of view in the 831 (and in my 839 last night) and in both scope, when the planet reached the edge of field of view and drifted beyond it.... no flaring! Am really, really impressed with this scope. I also like the depth of focus that it offers. It's just such a "comfortable" rewarding telescope.

 

(I also love the fact that I'm using a refractor that was built three years before I was born - and still going strong!)

 

Ant  :cool: 


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