Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Classic Jaegers in the Land of Synta

  • Please log in to reply
54 replies to this topic

#1 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 09 December 2015 - 08:16 AM

I’ve been living in Suzhou, China for a few years for work.  As a classics collector and something of an atm, I’ve had my hobbyist interests severely curtailed here.  Interestingly, on the other side of town from where I live is Suzhou Synta.  I haven’t been in-but here is an exterior of the main building along the street.  Synta has 3 or four other buildings on the site.  While scopes are made here-you can’t buy them locally.  Only online.

Attached Thumbnails

  • 1 Synta.jpg

  • Scott99, terraclarke, mitsos68 and 5 others like this

#2 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 09 December 2015 - 08:18 AM

To keep up (at least a little) with some scope building I brought along with me to China some Jaegers lenses from Surplus Shed.  I brought a 4inch F15 and a 6inch F10 (both were seconds and bought on sale).  I also brought some flats with the idea of making folded refractors-but this proved too difficult to do with the tools I could easily get together here.  A basic 2inch focuser from Meridian and a selection of eyepieces and a bino-viewer made up the rest of my imports to China.

Attached Thumbnails

  •  2 crown writing 6.jpg

  • terraclarke, mitsos68, TOM KIEHL and 1 other like this

#3 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 09 December 2015 - 08:19 AM

I’ll post some photos of the refractor builds using these Jaegers lenses.  The builds are pretty basic.  The more interesting part was experimenting with these classic lenses to get some idea of their quality, and working to get them to perform their best, again with very cheap, basic materials.  As an architect I am generally pretty fussy with materials and craftsmanship.  These scopes were liberating for me-allowing me to focus on the optics.

Attached Thumbnails

  • 3 two scopes king.jpg

  • terraclarke, TOM KIEHL, Bomber Bob and 3 others like this

#4 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 09 December 2015 - 08:20 AM

TSA was way too interested in these pieces of glass.  They nicely unwrapped everything, fingered them up well, and then gave me some snazzy TSA tape to keep.

Attached Thumbnails

  • 4 TSA.jpg

  • TOM KIEHL and happylimpet like this

#5 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 09 December 2015 - 08:22 AM

Being illiterate, I find shopping for scope making parts challenging.  Do-it-yourself home stores aren’t really a thing here.  What there is are little local shops with some basics.

Attached Thumbnails

  • 5 store.jpg

  • catboat, terraclarke, TOM KIEHL and 2 others like this

#6 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 09 December 2015 - 08:25 AM

I had taken David G's advice and ordered uncoated lenses from SS, with the idea that you could think of the lenses as polished blanks, should they not test so well.  I'm not an expert, but perhaps this one was a second because of coating issues...

Attached Thumbnails

  • 6 coatings.jpg

  • turk123, bremms, TOM KIEHL and 2 others like this

#7 bremms

bremms

    Fly Me to the Moon

  • *****
  • Posts: 5084
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 09 December 2015 - 10:26 AM

 Built my 6"F10 as a stop gap until my D&G 6" F12 was done. The lens proved to have a very good figure and Barry was way behind due to moving and other production issues. So I recently canceled my D&G F12 after a 3 year wait. I am very fond  D&G scopes and like Barry, but I realize these lenses are a side hustle for him. Had two 5" F12's from him and both were superb.  When I first used the Jaegers, I expected the 5" F12 D&G would easily outperform the 6" F10.. Uhhh Nope. the 6" F10 Jaegers had the same quality of figure and produced images that were a little better due to the increased aperture. It's a lifetime keeper.


  • Vesper818, orion61, starman876 and 2 others like this

#8 Bomber Bob

Bomber Bob

    Voyager 1

  • *****
  • Posts: 14164
  • Joined: 09 Jul 2013
  • Loc: The Deep South, USA

Posted 09 December 2015 - 11:39 AM

[SIGH]  I miss my D&G...

 

I had to have 2 x 4" refractors to deal with the loss.  (Naw, Debbie doesn't buy that line, either.)

 

Truth:  Barry sorta / kinda tried to talk me out of the f/10, tried to steer me to the f/12, but I dug in due to tube length & weight (was living in a two-story townhouse at the time).  His star test report to me stresses that he really worked the figure to minimize CA at that f-ratio - and I found that to be true.

 

My uncoated Jaegers 4" f/5 is a second quality, but it excels as an RFT.  Jaegers must have had some really good lens grinders, because from what I've read, their testing was very simple - especially compared to current methods.  I can't find it, but I once had a first quality 83mm f/15 in the original cell that I used to evaluate my Tasco (Towa) 80x1200.  The Jaegers was a cemented doublet that performed as well as the air-spaced Japanese objective.



#9 bremms

bremms

    Fly Me to the Moon

  • *****
  • Posts: 5084
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 09 December 2015 - 12:02 PM

I had my 4" F15 Jaegers out last night. It's a sweet lens too. Used it with a Nagler T5 31mm , ES 20mm 100 and an ES 14mm 100.  The Pleiades looks great at 50x with an 82 degree AFOV


  • Bomber Bob likes this

#10 Scott99

Scott99

    Aurora

  • *****
  • Posts: 4880
  • Joined: 10 May 2007
  • Loc: New England

Posted 09 December 2015 - 12:07 PM

wow, very cool thread!  thanks for updating us.  You are living next to the Synta factory and making telescopes out of 30-year old A. Jaegers lenses, that's crazy!   I think it would be cool to live in China and do architect work for a few years, what a great life experience.  

 

Is there anywhere to observe with dark skies?  are there any other amateur astronomers or clubs around??



#11 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:22 AM

Thanks for the comments.  Observing in Suzhou is pretty awful.  Light pollution, air pollution so thick you can cut it with a knife, and just being in the river delta make for poor conditions all the time.  The only plus is a few nights in late winter we get some remarkable stillness, and the moon can come through the haze pretty steady.

Interestingly, many high schools and universities have a dome prominently displayed on top of a main building.  The high school across the street from me has one (picture attached).  In 3.5 years it has never moved.  A new high school nearby has a bright golden dome.  I doubt it will ever move either.  As with many things in China, the appearance of having something is what is important.  Having it actually do something-maybe less important or not necessary.

Attached Thumbnails

  • 20 HS dome.jpg

  • happylimpet and mikeDnight like this

#12 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:33 AM

The 4 inch f/15 ended up being a Baker design with the large air space (photo).  Following all the postings on CN of people working with the Jaegers lenses, I found that there was quite a range of proposals for the spacing.  Not knowing what I had, I decided to just experiment and try a bunch of lens orientations and spacings.  I was surprised that I could get a somewhat decent image across a wide range of setups.

Attached Thumbnails

  • 7 Baker design 1.jpg

  • terraclarke, Bomber Bob, TSSClay and 1 other like this

#13 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:37 AM

The cell for both scopes are from PVC fittings, using carefully selected and placed dimensional pieces of known size to hold the lens.

Attached Thumbnails

  • 8  6in cell pieces.jpg


#14 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:40 AM

The 4 inch in the cell.

Attached Thumbnails

  • 9 lens in cell.jpg

  • terraclarke and Bomber Bob like this

#15 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:41 AM

Light baffles

Attached Thumbnails

  • 7 spacers for 4in.jpg

  • terraclarke and Bomber Bob like this

#16 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:44 AM

What not to do- use bamboo for the tube end/focuser mount.  Wood can be hard to come by normally- so I thought a cutting board would give me what I needed.  Swiss army knife in hand, I went to work.

Attached Thumbnails

  • 14 s6in tube end bamboo.jpg


#17 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:45 AM

The result works fine, but was way too hard.  I cleaned up the surfaces that needed to be exacting, and left the rest rough.

Attached Thumbnails

  • 16 focuser on 6.jpg


#18 Andrew Johnston

Andrew Johnston

    Explorer 1

  • -----
  • topic starter
  • Posts: 78
  • Joined: 17 Aug 2014
  • Loc: Central Virginia

Posted 10 December 2015 - 07:48 AM

Here is the 6inch being tested out the window.  PVC paints up pretty well with careful sanding.  The dew shield is extra long and is made from black card stock wrapped around mylar and hit with some spray paint.

Attached Thumbnails

  • 18 out window.jpg

  • Jim Curry, terraclarke, TOM KIEHL and 3 others like this

#19 Scott99

Scott99

    Aurora

  • *****
  • Posts: 4880
  • Joined: 10 May 2007
  • Loc: New England

Posted 10 December 2015 - 01:14 PM

The dome thing is interesting - we have a similar culture in boating here - everyone buys huge boats that sit at the dock all summer and never move!   :lol:



#20 jjbird

jjbird

    Messenger

  • *****
  • Posts: 473
  • Joined: 17 Jan 2006
  • Loc: Wisconsin

Posted 10 December 2015 - 01:42 PM

Nice work!



#21 terraclarke

terraclarke

    Hubble

  • *****
  • Posts: 18114
  • Joined: 29 May 2012
  • Loc: Third from the Sun

Posted 10 December 2015 - 02:15 PM

Great job! I made a short tube RFT refractor with PVC tubing and fittings and was quite pleased with the result. It's a nice material to work with. I hope you don't have problems with tube sag at the length you are using. How is the weight?

#22 DAVIDG

DAVIDG

    Cosmos

  • *****
  • Posts: 8333
  • Joined: 02 Dec 2004
  • Loc: Hockessin, De

Posted 10 December 2015 - 02:44 PM

  Andy, 

    Great to see your doing well ! The gang at both Stellafane and the Delmarva mirror making class all say  Hi. Great job doing the  ATMing. Like my tag lines states " Engineer = taking what you got and making what you need "   You can use your flat to test your lens setup to find the best spacing. 

 

             All the Best,

               - Dave 



#23 bremms

bremms

    Fly Me to the Moon

  • *****
  • Posts: 5084
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 10 December 2015 - 03:07 PM

The 4 inch f/15 ended up being a Baker design with the large air space (photo).  Following all the postings on CN of people working with the Jaegers lenses, I found that there was quite a range of proposals for the spacing.  Not knowing what I had, I decided to just experiment and try a bunch of lens orientations and spacings.  I was surprised that I could get a somewhat decent image across a wide range of setups.

Normal air space on the jaegers 4" is about 0.130" that is the thickness of the provided spacer. 0.130 is about right for a Baker design. The spacing you are showing is more like a Clark design or even wider spacing.



#24 DAVIDG

DAVIDG

    Cosmos

  • *****
  • Posts: 8333
  • Joined: 02 Dec 2004
  • Loc: Hockessin, De

Posted 10 December 2015 - 04:37 PM

 I have  the  Baker f/15 design entered into OSLO  from the parameters listed in "Telescopes and Accessories" by Baker.  The air gap thickness is 0.003110 x the focal length so for a 4" f/15 lens with 60" focal length the spacing works out to be 0.1866" or  3/16". 

   In the Baker design R2 and R3 have the same radius with one being concave and the other convex. So you can test the concave one directly with a Foucault test to be sure it is spherical and also measure the exact radius of curvature and then it use to test the convex one by placing them in contact under monochrome light to observe the interference fringes. For 4" f/15  the two inner radii should be 21.509"  if the glass is BSC2 and DF2.

  If you have an optical flat that  is close to the diameter of the lens or larger then you can test the complete lens by double pass autocollimation. This test will quickly allow one to find the air gap that shows the best correction.

 

                            - Dave 


Edited by DAVIDG, 10 December 2015 - 05:31 PM.

  • bremms and Andrew Johnston like this

#25 bremms

bremms

    Fly Me to the Moon

  • *****
  • Posts: 5084
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 10 December 2015 - 04:55 PM

The spacer is 0.185 on the 4" The 3" is 0.135. Measured the 3" F15 lens spacer I have. My notes indicate 0.185 for the 4" F15. So Baker it is. The 6" lenses are Fraunhofer doublets.


  • Bomber Bob likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics