GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Well, I can't fight it any longer. I would like to build a longish focal length refractor. I am looking at 5" f/12-f/15. I have e-mailed D&G about a lens and cell. No word back yet. I am wondering if there are any other suppliers who you guys have tried and can recommend just in case I need to.
This is my first foray into refractor building. I have built quite a few Dobs though. My heart is into refractors so I've got to do one.
I will be obliged for any help.
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Glen
www.lyraoptic.co.uk
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Glen,
I understand you want to make a refractor, but have you considered a Schief?
You'd get an even longer focal length, ie f27 - so more magnification out of long eyerelief relatively simple design eyepieces, no false color, easy collimation (much easier than a Newt), probably lighter weight and a shorter OTA, and a lower (maybe much lower) cost.
Here's Dave Groski's and mine at this year's Stellafane:
(I believe Dave had his on Venus at mid-day - not sure if that's the case in this shot though it looks like it - and it looked fine.)
Gary
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Hi Gary,
I've not done any research on this system before. I have seen a few though. Certainly interesting. I don't really want to go down the road of making my own optics. Are there suppliers of optics for this system?
Thank you for the link.
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Glen
www.lyraoptic.co.uk
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John Jarosz
Astro Gearhead
Reged: 04/25/04
Posts: 2287
Loc: Chicago area, IL
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A 5" F12 or so refractor is going to need a really robust mount. Have you considered building it as a folded refractor? Not as classic in appearance as a traditional design, but the length is much more manageable. You do need a good flat mirror that's half the diameter of the objective. It would be an extra cost, but I think the shorter length would allow the scope to be used more often.
John
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6" F4.6(w/Paracorr) GEM reflector, 8" F11 Dall Relay Scope
6" F5 RFT Refractor, Garrett Gemini 20x80 LW
Edited by John Jarosz (08/19/09 07:32 PM)
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3120
Loc: Northeast
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Gary, your pics aren't showing. Format too large?
Mark**************
NEVERMIND! they are now. (?!@#*)
Didn't know the other was yours!
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So many projects, so little time!
Edited by Mark Harry (08/19/09 07:41 PM)
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Hi Glen,
Quote:
Are there suppliers of optics for this system?
I don't know if there are any current off-the-shelf suppliers of Schief optics though there is at least one manufacturer of complete scopes on the continent, just can't recall the name right now. There are a few CN'ers here that should be able to make you a set.
As for the mechanics, there are some things to pay attention to, and obviously it's not Newt-like, but on the whole I think comparable or even easier to build than many common Newt designs, though not as simple as putting a cell on a tube, some baffles and a focuser on the other end...
(I think - and there's been a good amount of discussion about this, much of it by people who haven't made them - that a Schief set can be a fairly challenging project for your first mirror; but if you have some experience and avail yourself of guidance, very doable.)
Gary
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Mark,
Sorry for any trouble with the pics. Maybe some issue with my host? Sometimes they come up normally and sometimes I have to refresh or reload the page.
I heard you were at Stellafane. I was hoping to say hello to you and Kevin Frederick at least and put some faces together with names. Next year...
I had my scope on the hill near Dave's Schief and 6" f4 and Matt Considine's Schupmann on Saturday, and right outside the clubhouse next to Dave's scopes and Dick Parker's refractor on Friday night.
Gary
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timo4352
super member
Reged: 04/16/07
Posts: 160
Loc: Northeast Ohio
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Hi Glen
This group will help fuel that urge:
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/?yguid=332121599
Tim
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Orion 3.6CA Reflector
and 2 homebrew scopes --
8" Hubble Bubble ballscope
8" F/8 CHief - nearing completion 
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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A 5" at f/12 or even f/15 will be OK on a G11 mount if you use a Hargreaves strut. D&G makes excellent doublets.
Plenty of people here who can help you. Go for it!
Scott
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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I have had an e-mail from Barry at D&G giving me a time line for a 5" f/12. It's 6-8 months. I suppose it would give me time to get things organised.
Thank you all for your suggestions and links so far. I am finding the options very interesting.
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Glen
www.lyraoptic.co.uk
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 658
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get hold of ED JONES and go CHief he has a great 6 inch that maybe he will sell /bet it will SMOKE that refractor /in every way /smaller /no color /no obstruction/ kevin
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Mike I. Jones
Carpal Tunnel
Reged: 07/02/06
Posts: 1572
Loc: Fort Worth TX
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Glen,
I'm actually surprised Groski hasn't honked his Schupmann horn at you as well 
Rather than choosing one configuration here, I'd say follow your initial desire and make that refractor, THEN the Schief, THEN the Chief AND the Schupmann!
Newport Glass sells pregenerated 4", 6" and 8" achromat kits with full tooling at http://www.newportglass.com/angwcat.htm. My recommendation: do the 6" aperture AAB6.15 kit. Twice the light for the same amount of effort.
Also, go back through the ATM forum and look for James Champagne's very thoroughly documented story of building his 6" refractor as part of his Physics degree. PM him and get advice from him, he's a great guy.
I just joined the Yahoo http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ group and there's a lot of good info there as well.
I agree on the performance of the alternate configurations suggested, they are all great scope designs. But they are simply well-meaning recommendations - you should build exactly what you want. I made a 6" f/10 achromat myself and yes, the secondary spectrum is there, but it still gives beautiful images. A Schief, Schupmann and Chief are all on my to-do list as well.
Mike
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56 mirrors, lenses, 16" f/6 Newt, 6" f/10 refractor, TOA-130S, Tinsley 5" f/15 Mak, 6" f/4 RFT, Coronado PST. Still to build: 24" f/10 Modified Dall-Kirkham, 10" f/26 Mak, 8" f/12 apo, spectrohelioscope, Herrig, Schupmann, and others.
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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I think I'm going to join the Yahoo group and see how it works out. I have been speaking to a couple of people today and they have said to go for the f/15 version. I think they could be right.
I will also be making my own alt/az mount for the scope.
It is good to hear all the views of the dedicated people on CN. What an excellent site. I am delving into past threads tonight.
My better half found out about the project today! I had to mention it due to the fact a large piece of aluminium tubing may be turning up in the next few days. The eye will soon heal.
All suggestions are welcomed.
Thank you all 
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Glen
www.lyraoptic.co.uk
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8306
Loc: Bremerton Washington
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Quote:
I think I'm going to join the Yahoo group and see how it works out. I have been speaking to a couple of people today and they have said to go for the f/15 version. I think they could be right.
I will also be making my own alt/az mount for the scope.
It is good to hear all the views of the dedicated people on CN. What an excellent site. I am delving into past threads tonight.
My better half found out about the project today! I had to mention it due to the fact a large piece of aluminium tubing may be turning up in the next few days. The eye will soon heal.
All suggestions are welcomed.
Thank you all
Glen..go for it. 5"f/15 is a great performer and still retains that eligant refractor feal/look. It's objective is farely forgiving in its design and fabrication. I have a pretty slick website I will find that helps you all along the way to building your scope.
The Yahoo group is dedicated to those who build their own and there is plenty of help and encouragement there.
I too am building a 10"f/15 along with many other things.
My intent is to build the ojective myself. Currently I purchased an objective..but am going to make the 10"f/16 for another scope on the books.
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8306
Loc: Bremerton Washington
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Glen...check this website out and save it as a favorite...it is extremely helpful in fabriaction of your scope.
http://bobmay.astronomy.net/refractor/Refrindex.htm
Rob(good luck)
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Quote:
I will also be making my own alt/az mount for the scope.
Do you mean one that tracks? If not, at modestly high magnifications for a 4" or 5" (~125X - 175X or more) I find it very distracting to almost constantly reposition. And with the adjusting a 5 or 6 foot scope will probably take a bit of time to settle.
For example, when we set up Friday night at Stellafane two of Jupiters moons were tough to separate staying put; it would have been much harder or impossible manually moving the scope.
My Schief is probably as heavy as your refractor will be or close, though shorter, and while I'd like more it does okay on an old RV-6 GEM.
Gary
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8306
Loc: Bremerton Washington
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Quote:
Quote:
I will also be making my own alt/az mount for the scope.
Do you mean one that tracks? If not, at modestly high magnifications for a 4" or 5" (~125X - 175X or more) I find it very distracting to almost constantly reposition. And with the adjusting a 5 or 6 foot scope will probably take a bit of time to settle.
For example, when we set up Friday night at Stellafane two of Jupiters moons were tough to separate staying put; it would have been much harder or impossible manually moving the scope.
My Schief is probably as heavy as your refractor will be or close, though shorter, and while I'd like more it does okay on an old RV-6 GEM.
Gary
Gary...did you grind your secondary against the primary to get its curve correct?
I have an 8"f/13 mirror I'm considering using for a Schief.
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Gary,
I don't intend to make the alt/az a tracker at the moment. This of course may change in the future.
Rob,
Thank you for the links. Plenty of reading to do.
I didn't really want to grind my own lens. Just depends how this project goes. You never know.
Thank you all
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Glen
www.lyraoptic.co.uk
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Quote:
Gary...did you grind your secondary against the primary to get its curve correct?
Hi Rob,
Yes. Glass on glass. Then polished the concave primary and tested for sphericity and radius with knife edge and Ronchi. Then polished the convex secondary and interference tested it to match the curve of the primary.
Gary
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Quote:
I don't intend to make the alt/az a tracker at the moment.
Rob, you have a long refractor or two don't you? What do you think about tracking vs not for high magnification viewing?
Gary
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8306
Loc: Bremerton Washington
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Quote:
Quote:
Gary...did you grind your secondary against the primary to get its curve correct?
Hi Rob,
Yes. Glass on glass. Then polished the concave primary and tested for sphericity and radius with knife edge and Ronchi. Then polished the convex secondary and interference tested it to match the curve of the primary.
Gary
Nifty part is you grind in simple spheres as I recall..because of the long focal lengths.
I could make a tool from the existing final ground 8"f/13 mirror. and make the secondary convexed by way of it.
Interesting....hmmmmm
Or...I have an f/10 cast iron tool...I cood tool up to grind the secondary..and then test it.....Hmmmm
How big a Schief have you made and how big can you theoretically go?
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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Biff
Carpal Tunnel
Reged: 09/04/05
Posts: 2372
Loc: Courtice, Ontario
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Quote:
...easy collimation (much easier than a Newt)....
Really? I've always wondered how you collimate a sheif... have any plans for your design anywhere?
Thanks
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Ryan
Antares 200mm f/6 Dob & 130mm f/5 Travel Dob.
Projects on the go...
- a couple 80mm SS refractors on the back burner.
- a few small mirrors awaiting polishing
- 260mm f/7.15 mirror... still polishing
Member of DRAA
 My house.
 DRAACO
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8306
Loc: Bremerton Washington
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Quote:
Quote:
I don't intend to make the alt/az a tracker at the moment.
Rob, you have a long refractor or two don't you? What do you think about tracking vs not for high magnification viewing?
Gary
Track...track..track. An example is my last party here...I was viewing Jupiter using a 32mm EP for my scope that gives me about 71X..not bad..but not high mag. When I used my 5mm the mag shot up to 457X. You had better be tracking or by the time you locate the target it will have scooted across the field of view before you can let someone else take a look. 
What's worse...is the inability to really study the high resolution images...because they are clipping along.
I think If you're gonna make a simple alt/az mount..you had better create it with a wedge..so you can build a simple tracking system.
IMV a high power long focus refractor needs tracking..if you want to really enjoy the wonderful images.
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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The wedge is something I never thought of. That is a good idea. Certainly something to give a coat of looking at.
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Glen
www.lyraoptic.co.uk
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Hi Ryan,
Quote:
Really? I've always wondered how you collimate a sheif... have any plans for your design anywhere?
Collimation is pretty easy:
Insert laser and hit center of secondary.
Adjust secondary to put laser spot on the center of the primary.
Adjust primary to put the spot a specific distance above the secondary. For this last step I have an L shaped piece of aluminum with a small hole at the right height and I slip it over the secondary tube and hold it with a rubber band.
Mine holds collimation quite well even though it gets moved and bumped around a lot.
For several designs, including ones by Dave Groski (I made his 4 1/4" one) see the "Files" section here.
Gary
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Quote:
Nifty part is you grind in simple spheres as I recall..because of the long focal lengths.
Yes, so primary testing is for a knife edge null or straight Ronchi lines, and secondary by interference - no data reduction, masks, software, etc.
Quote:
I could make a tool from the existing final ground 8"f/13 mirror. and make the secondary convexed by way of it.
I'm a little out of my depth here but I think that it could be tricky to start with a finished primary: assuming of course it's the correct radius.
I think you want to get through fine grinding with the curves matching as closely as possible - which they would be - and, also as near to target radius as possible, maybe a little long on the primary.
To check you can flash polish the primary and use the knife edge and then go back to grinding if needed. That way you'd know that the convex secondary "tool" was a pretty close match. You could probably do it with a spherometer but you'd need a very accurate and very well calibrated one and even then you might be off enough to have a lot to correct in polishing. I'm not saying you couldn't do it, just that most likely it would make something fairly simple and straightforward harder by an unknown (to me at least) amount.
Quote:
Or...I have an f/10 cast iron tool...I cood tool up to grind the secondary..and then test it
See above comments. Also these are quite shallow curves so matching up a cast iron tool could need to remove a lot of glass you don't have to.
Quote:
How big a Schief have you made and how big can you theoretically go?
Mine is Dave's 4 1/4". I've seen some variation in claims for max size and actually don't remember the claims. It seems like with the larger sizes you start to need to fold them to keep the size manageable and I'm not keen on that because of the extra surface. Then again, for you Rob big long scopes don't seem to be an issue!
Gary
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1414
Loc: Sin-sin-atti
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Glen,
If you're not into polishing glass you can always build a 6 inch f/8 Chief and just buy the primary and lenses. It won't have the color halos of a refractor, you can put it on a GEM or Dobsonian mount. Not as easy as a Newtonian but even if you can't make it work it can be make into a Newtonian. The design is posted on the spiderless group if you're interested.
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Ed Jones
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Well the tube arrived this morning. Still wrapped up at the moment.
Outside diameter 6"
Weight is 40oz per foot.
Wall thickness is .125"
Length at the moment is 99"
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Glen
www.lyraoptic.co.uk
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3450
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Hokey Jeebers! That's a chunk of tubing! 
Ryan- Gary's correct- collimating a Schief is easy. (So easy a caveman can do it! ) As a final check, tweak the primary on a star test... it's very easy, because the primary collimation screws are right there within a few inches of your eyepiece. That last little tweak will perfect your collimation.
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Wes
Atlantic Beach, FL
Some bino’s from Miyauchi 5x32 Binon's up through Garrett 20x110 Signature's,
Some telescopes from a Stellarvue 80mm NHNG up through a couple of 8” reflectors…
And a wonderful 4.25" Delmarva Shiefspiegler!
Some good friends, made here on C/N.
Oh- several cats and a wonderful wife!
Anyone want a cat???? :-O
"When your work speaks for itself- Don't Interrupt" -Gamble Rogers
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Mason Dixon
member
Reged: 06/29/07
Posts: 43
Loc: Huntsville, Alabama
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How do Schief's compare to Schupmans?
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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Quote:
Well the tube arrived this morning. Still wrapped up at the moment.
Outside diameter 6"
Weight is 40oz per foot.
Wall thickness is .125"
Length at the moment is 99"
Very nice Glen.
Wall thickness is a bit more than you really need.
I am pretty sure that D&G optical uses 0.06" or 0.07" tubing for their refractors. Check their website.
Anyway, better too thick than too thin.
I made bayonet connectors for my 6" refractor so the objective lens comes off like a camera lens coming off a camera body. The OTA seperates into 3 pieces with ease. I don't have pics on this computer and I am heading out for a week. If you are really interested in what I did, drop me a PM and I will get pics.
Good luck,
Scott
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Hi Scott,
Yeh,the tube is a little heavy gauge wise. It's just that stockists in the UK are few and far between for anything these days. I thought I was lucky to source this tube.
I will have to make an adapting collar of some type I'm sure.
Thank you for the offer I'll PM with my address.
My Ali came from here www.AluminiumWarehouse.co.uk
Thank you Scott.
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Glen
www.lyraoptic.co.uk
Edited by GlenM (08/22/09 04:01 PM)
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3450
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Just to add one additional/final thought on collimation of a Schief- one tip that Dave Groski gave me when I took mine out the first time, was- after initial collimation with the laser, take the laser/eyepiece out, just have a 1.25" eyepiece adaptor in the focuser (if you have a 2" focuser) and look through the focuser. If you can see any of the walls of the secondary tube coming into the FOV of the primary, simply tweak your primary outward until you no longer see the secondary tube in the primary mirror. Makes more sense when you're doing it than trying to explain it. Adjusting the primary for the specified 2-something inches away from the secondary is kind of doing the same thing- this is simply a check to ensure you've tilted the primary away from the secondary tube an adequate distance. You don't want to see the reflection of the end of the tube in the primary. Then the final star test to tweak it in.
Takes much longer to describe than to do.
Wes
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3450
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Quote:
How do Schief's compare to Schupmans?
Dave Groski's probably one of the few who has both- and the building/viewing experience with both. He'd probably be the best person to answer your question.
Wes
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Well, I unwrapped the tube today. I have just had about 20 minutes with the metal polish. I think it's going to polish up very nice.
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Glen
www.lyraoptic.co.uk
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8306
Loc: Bremerton Washington
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Quote:
Well, I unwrapped the tube today. I have just had about 20 minutes with the metal polish. I think it's going to polish up very nice.
Yeah....Glen. I tried that with my 12" tube from hastings and it turned out nasty. The more I polished the more I revealed surface defects.
It would have taken me a year to polish out my 12" X 14ft tube.
Yours looks sweet.....
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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I've done a little more and it looks as though I might get away with it. I must say that I do like the Celery Green. Looks the bee's knee's.
Joined the homemade group this morning. A bit busy to have a good read at the moment.
Regards.
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Glen
www.lyraoptic.co.uk
Edited by GlenM (08/24/09 03:19 PM)
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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I wonder if your tube may be extruded because of it's wall thickness. The irrigation pipe we use in the US is rolled and welded. It has a seam that needs to be filled to be smooth. The thicker the pipe, the worse the seam is.
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Yes,it's extruded. No sign of a seam at all. I'm using Solvol Autosol and Auto Glym with a nylon pan scrub. I'll probably finish with just a buffing cloth.
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Glen
www.lyraoptic.co.uk
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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Quote:
Yes,it's extruded. No sign of a seam at all.
Then you are in good shape for polishing that puppy out.
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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A little update on the lens/cell.
I have now ordered from Ales at IStar the 6" f/10. I thought things through and decided this was the way to go with my first build.
Ales sources his lenses from Asia at the moment,although he does want to source from Germany in the future.The cells are made in Europe and built in the States,so I'm led to believe. It seems there have been three orders for the 6" f/10. One from Aus,one from the States and me in the UK.
I would still like to build the 5" f/15 though,if only D&G would answer my e-mails.Must be pretty busy.
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Glen
www.lyraoptic.co.uk
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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D&G may be on vacation. They will answer and get back to you. Sometimes they are slow. I have found that their lenses are definitely worth the wait.
I personally like the f/15 better due to less color.
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Hi Scott,
The 5" f/15 is still in the future,So I can hang on a while for an answer.
Did you receive my PM about the pics of your cell mounting system?
Regards.
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Glen
www.lyraoptic.co.uk
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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I did Glen.
I am on vacation until next week.
The pics are not on this computer. I will send them next week. If you don't hear from me, please remind me!!
Scott
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Yeh,you did mention the holiday. It's me having another senior moment.
Thanks Scott.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Just a little update.
I have done some polishing of the tube. I trimmed the bad end off the tube using the drawing paper and hacksaw method and it worked a treat.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Another.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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I have decided to buy a focuser this time round. I have gone for the Skywatcher Crayford. I have one on my Equinox 120 ED and it works a treat. Next one I'm going to make.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Another.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Down to my mates lathe next week to do some turning for the focuser end plate. Looking forward to doing the machining.It's been a long time since I was "on the tools".
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Glen
www.lyraoptic.co.uk
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Dick Parker
sage
Reged: 08/17/07
Posts: 247
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Glen -
I like the polish job on your tube. From what I have recently read on CN, aluminum acts better thermally if left un painted. I am going to try to polish the tube on the 4.5 inch refractor that I just made (photo attached). It is a Hastings tube, so polishing it might not be as easy, but I'll try.
How do you plan to protect the tube from finger prints and other corrosion?? clear coat it??
I think you will enjoy your refractor. Obviously they are not light buckets, but for splitting double stars and planetary detail, plus just overall ease of use, refractors are hard to beat. The one pictured is 4.5 inch f/15 with K5 and SF1 glass. The elements are oil spaced for 10% increase in light through put (over uncoated elements), and the design is such that (at 4.5 inch f/15) the three colors normally in the design range can be focused to meet in the same size disk slightly larger than the Airy disk. This means that for visual viewing, there is essentially no noticable color.
Good luck
Dick Parker
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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That looks like a nice set up Dick. Yes at f/15 I would think the colour is minimal. We will have to see what the IStar 6" f/10 is going to produce. I think I may need a couple of Baader filters.
From what I've read here on CN the Hastings tube do show a seam. With mine being extruded there is nothing to be seen. I found Solvol Autosol to be the best polish/abrasive much better than Autoglym.
Not sure what I am going to do to protect the finish. Laquer could be the way to go although Solvol Autosol does leave a protective film. I used to use it years ago on my Motorbikes.
Enjoy your new scope Dick and clear skies.
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Glen
www.lyraoptic.co.uk
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chuckscap
sage
Reged: 07/18/09
Posts: 213
Loc: Colorado Springs, CO USA
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D&G has always provided first class optics. My dream telescope is their 20" Classical Cassegrain.
Chuck
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plyscope
sage
Reged: 11/23/06
Posts: 326
Loc: Perth, West Australia
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Hi Glen
I recently received an email response from D & G. They are currently expecting a 6-8 month delivery status on 5" f15 lens in cell. I am ordering one myself. I can also testify they are worth the wait.
Dick, I like your refractor. Is there a thread on the construction?
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Andy
6" f15 refractor
90mm f16.7 refractor
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neo
professor emeritus
Reged: 02/12/08
Posts: 609
Loc: Iasi, Romania
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Glen, that's a beautiful project you have there.
The tube looks exquisite!
One little question though...you mentioned earlier about trimming the tube by drawing paper and hacksaw method. How exactly you do that? I'm interested cause I have to trim some aluminum tubing myself and it's first time I hear about that method.
Thanks!
Alex
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Hi Alex,
Well,I have done more polishing of the tube and have now finished the focuser plate(polished of course)
I read a post about cutting the aluminium tube here on the forum.
I used a sheet of drawing paper long enough to go around the tube with a 50mm overlap. When you overlap make sure the paper is square to the tube. I then used masking tape to stick it to the tube on the opposite to where I was making the cut. Just make sure the drawing paper is secure and will not move.
Use an OLD hacksaw blade(a new blade will pick up and jam) and work your way around the tube just scoring into the aluminium until you have a groove. Don't try for a through cut or the blade will jam. Just keep going around the tube scoring deeper all the time. Just let the hacksaw do the cutting and take it slow. You will feel when the blade nears the cut through so take extra care and have a look inside the tube you will see a line where the blade is pushing out the aluminium. It took me about an hour for the 6" tube. The result was very good.
Hope this helps a little Alex.
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Glen
www.lyraoptic.co.uk
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Dick Parker
sage
Reged: 08/17/07
Posts: 247
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Andy-
"..Dick, I like your refractor. Is there a thread on its construction?.."
I had no thread specifically on the construction of this telescope. But, may I invite you to visit my website (actually space on my son's) at "http:/mirrorworkshop.mtbparker.com/index.html" and click on the tab under "refractor story" that shows the construction of my 6 inch f/15. The 4.5 inch discussed in this thread is a little brother to that one and the construction details are quite similar. Included are photos of the completed 6 inch refractor and a schematic of the lens cell.
The 4.5 inch lens is slightly different in that it uses K5 and SF1 glass and the elements are oiled, whereas the 6 inch is a Baker airspace design.
Follow up on the polishing. I did polish the tube. It was more work though, than Glen describes. I had to use 220 sandpaper to start to remove al the tube blemishes, then 400 paper, 600 paper, then polish. Quite a job, but it came out OK. Last week I had the telescope out and was able to see Neptune, Uranus, Jupiter, Juno, and many double stars with it. Stars at 250X were pure round Airy disks. Separating doubles was fun. Before the night was over, the mount, finder, tripod, everything around was covered with dew, but the tube was not. I guess there is something to the idea that polished aluminum behaves better thermally, especially if polished.
Dick Parker
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neo
professor emeritus
Reged: 02/12/08
Posts: 609
Loc: Iasi, Romania
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Quote:
Hi Alex,
Well,I have done more polishing of the tube and have now finished the focuser plate(polished of course)
I read a post about cutting the aluminium tube here on the forum.
I used a sheet of drawing paper long enough to go around the tube with a 50mm overlap. When you overlap make sure the paper is square to the tube. I then used masking tape to stick it to the tube on the opposite to where I was making the cut. Just make sure the drawing paper is secure and will not move.
Use an OLD hacksaw blade(a new blade will pick up and jam) and work your way around the tube just scoring into the aluminium until you have a groove. Don't try for a through cut or the blade will jam. Just keep going around the tube scoring deeper all the time. Just let the hacksaw do the cutting and take it slow. You will feel when the blade nears the cut through so take extra care and have a look inside the tube you will see a line where the blade is pushing out the aluminium. It took me about an hour for the 6" tube. The result was very good.
Hope this helps a little Alex.
Thanks a mill Glen! Most appreciated 
I was thinking about wraping the paper around the tube but wasn't sure. I used before a quiet similar method with a plywood sheet as a guide. The plywood had a hole with the same diameter as the tube. But now I don't have the plywood.
Thanks again! Good luck farther with your project, I sure enjoy reading it
Alex
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Alex,
Always pleased to help if I can.
Dick,
I think I was lucky with the tube. It was in pretty good order when I unwrapped it. I have done some more polishing I can only assume that a seamed tube is a lot more difficult to polish. Good to hear your scope is performing well.
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Glen
www.lyraoptic.co.uk
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Scott Watson
sage
Reged: 05/26/06
Posts: 279
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I think Newport still sells 5" achromats either mounted or unmounted. I think they are around $1000. each.
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PitchHitter
member
Reged: 09/23/09
Posts: 23
Loc: Southern Sierras
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Quote:
Glen -
I like the polish job on your tube. From what I have recently read on CN, aluminum acts better thermally if left un painted. I am going to try to polish the tube on the 4.5 inch refractor that I just made (photo attached). It is a Hastings tube, so polishing it might not be as easy, but I'll try.
How do you plan to protect the tube from finger prints and other corrosion?? clear coat it??
Good luck
Dick Parker
Hi Guys:
I introduced the tube cutting method at RTMC in 1973 when I displayed my in progess 11" f:2.8 SC. I like to use a roll of paper so I can get a couple of wraps or more and that helps define one edge to drag the hack saw blade along. After Xmas rolls of wrapping paper are also good for this as well as diagraming an optical and tube layout. I take the end of paper, fold it in half to mark the center with a crease. I then tape the crease onto the tube with the edge of the roll where I want to cut. It is absolutely important that the paper over laps so the edge can be determined square with the tube. If two wraps perfectly overlap then you can be very sure. I do similiar for squaring optics in a tube or mounting. I first posted this on line I believe in the astro-cafe forums maybe 15 years ago?
Now as for the aluminum tube. I sure love the polished aluminum look but it must be protected because it seems like the better it takes a polish the easier a handprint will stain. I always wound up priming and painting the tubes. I never had much luck with ordinary carnuba wax but there is an amazing aluminum polish sold through RV suppliers. Sorry I don't remember the name but Camperland should have it. There is another version for stainless steel and brass.
BUT! five seconds after someone touches the tube and for about five minutes afterwards there will be terrible tube currents and someone just being closs can do the same thing. I had to insulate my Newtonian because one could not help but get close to the tube. With the refractor you may not have to worry so much but it is worth remembering if you have problems. Best,
Rick
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About 20 telescopes from a 200mmAPO up
Fav is Meade 10" f:4.5 using my 3" 40mm 96°AFOV
BUT! In Progress:
14.5" f:5 grab n' go with DSCs will offer 2.4 degrees at 45 power and 8mm exit pupil (Light Bridge Buster)
16.25" f:7.5 to refigure
(20th wave ruined in a fire at the coaters)
22" f5: New mount almost done
(old all aluminum mount was stolen)
16" Varian Vapor Deposition Coater.
Looking for larger chamber.
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Well,the IStar 6" f/10 Achromat lens and cell arrived this morning.
It was VERY well packed.
A couple of dimensions:
Diameter rear of cell 168mm
Diameter collimation ring 190mm
Diameter front of cell 168mm
Width of cell 53mm
Weight of cell 5lb 9oz
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Another
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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A couple of pics of the rear end,the OTA rear end that is.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Another quick one.
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Glen
www.lyraoptic.co.uk
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neo
professor emeritus
Reged: 02/12/08
Posts: 609
Loc: Iasi, Romania
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Good Lord !!
That looks amazing! Simply astonishing!
It looks like it was made in a high tech lab.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Progress at last.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Cell and countercell.
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Glen
www.lyraoptic.co.uk
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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As they say around here,tother end.
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Glen
www.lyraoptic.co.uk
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plyscope
sage
Reged: 11/23/06
Posts: 326
Loc: Perth, West Australia
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It looks like a very special telescope Glen, well done. You could sell a truckload if you went into production! Looking forward to first light report.
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Andy
6" f15 refractor
90mm f16.7 refractor
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4065
Loc: S. Philadelphia, PA
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Gorgeous scope! I can imagine taking a long exposure picture of the scope itself with the Milky Way reflected in its surface... - j
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
Eero2-a 6" f/5 ball-scope you probably can't. 
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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Looking very nice Glen.
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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Quote:
From what I have recently read on CN, aluminum acts better thermally if left un painted.
I am not sure polishing is going to help much on a refractor. See article here:
http://www.garyseronik.com/?q=node/55
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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Don't say that now I've polished the monster 
Thank you for all your nice comments guys.
Clear Skies.
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Glen
www.lyraoptic.co.uk
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polaraligned
sage
Reged: 12/26/08
Posts: 227
Loc: P. R. of New Jersey
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Just think, if you have that thing anodized the polishing will make the finish a whole lot nicer. 
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GlenM
Vendor
Reged: 05/20/07
Posts: 1734
Loc: Lancashire UK
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What a terrible thing to say 
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Glen
www.lyraoptic.co.uk
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