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Equipment Discussions >> ATM, Optics and DIY Forum

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Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: 9.25 inch refractor project new [Re: Mike I. Jones]
      #5780974 - 04/06/13 12:42 AM Attachment (55 downloads)

Here's the OSLO file that includes the wedged airspace, in case you wanted to doodle with it.

Jim, that's one fine lookin' refractor image. Let's see some Moon shots as soon as you are able to!

It was an honor to work with you on this project. You're an A+ optical worker for sure.

Mike


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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project new [Re: Mike I. Jones]
      #5780977 - 04/06/13 12:44 AM Attachment (69 downloads)

I did see that Mike in the star images during star testing.

This is your design Mike, come to fruition. As soon as the moon comes into view again I'll get some shots of it, maybe even Jupiter. After a week of sunny clear weather we have gone into the usual Alaskan cloudy stuff with snow on the way. We only have until April 24rth at the latest for night skies then it is just too light except for the moon and bright planets. By this coming fall I should have the scope mounted up and ready for some real use as well as imaging.

Here are a few of the scopes I have available to me along with the 127 APO, a six inch refractor I made and the 9.25 inch refractor. The blue scope is my 12.5 inch reflector which has awesome optics and is equipped with a 5 inch Surplus Shed refractor, a 90 mm refractor and a 50 mm finder. It takes excellent images and is easy to set up for imaging. I am really spoiled here ! The 26 inch reflector is in the background and also has excellent optics which produce great images when the atmosphere allows it. I made all of the 26 inch components except for the diagonal mirror as well as all of the 12.5 inch components except for the lenses and the diagonal. There is something about working with glass that I just really enjoy.

Edited by jimegger (04/06/13 02:39 AM)


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Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: 9.25 inch refractor project new [Re: jimegger]
      #5781180 - 04/06/13 06:17 AM

Jim, what a difference in the last 2 mountain pics!!!
I'm impressed!!! Nice work.
(quite a stable of scopes there, too.
M.


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Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: 9.25 inch refractor project new [Re: Mark Harry]
      #5781305 - 04/06/13 08:49 AM

Man, lookit them polar axis angles almost pointin' straight up! You could almost just put a rock under the south side of a Dobson and be equatorial!
Mike


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Old Will
sage


Reged: 02/12/10

Loc: Utah
Re: 9.25 inch refractor project new [Re: Old Will]
      #5782439 - 04/06/13 07:16 PM

I weighed my 9,5" achromat blank set ,, it is 12.6 lbs
The set is SK18A & SF5 11/16" thick. When I make it I am thinking of f/20 = 180". I am going to tri-fold it down to a 60" OTA. First though I am going to use my other achromat sets, a 6" & an 8" to gain experience. I'm also wanting to avoid excessive moment arm torque,, cheers. Will


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Old Will
sage


Reged: 02/12/10

Loc: Utah
Re: 9.25 inch refractor project new [Re: Mike I. Jones]
      #5782446 - 04/06/13 07:19 PM

Mike can you give me the radii multipliers for 4" achromat using SK51 & DF2 ,, is DF2 different than F2? I have three sets, they were gifts

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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project new [Re: Old Will]
      #5787286 - 04/09/13 02:25 AM

I weighed the objective in its cell and it came to 15 lbs.

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herrointment
Post Laureate
*****

Reged: 03/12/11

Loc: North of Hwy. 64
Re: 9.25 inch refractor project [Re: jimegger]
      #5787805 - 04/09/13 10:53 AM

Dude, you deserve some kind of an award!

Incredible!


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Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: 9.25 inch refractor project new [Re: herrointment]
      #5789658 - 04/10/13 06:42 AM

Jim, how long has this project taken?
2 years?
M.


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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project new [Re: Mark Harry]
      #5790725 - 04/10/13 05:02 PM

Mark, it took a year and a half. A lot of that was time off from it though and I had a couple of glitches with chipping blanks etc. Actual labor time in the glass itself is about 90 hours. It was well worth it !

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Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: 9.25 inch refractor project new [Re: jimegger]
      #5790907 - 04/10/13 05:51 PM

You mean, so far, or are you DONE??!!

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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project new [Re: Mike I. Jones]
      #5791484 - 04/10/13 10:36 PM

Mike , I may be done after this next test but it is so close that it is not going to be much longer. It is giving nearly identical star test images inside and outside focus. Star images are very tight to where it easily splits Castor and has improved even more with the last test. I am still awaiting clear skies to evaluate the last 15 minute correction session.

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MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: 9.25 inch refractor project new [Re: jimegger]
      #5791818 - 04/11/13 07:01 AM

Quote:

I may be done after this next test but it is so close that it is not going to be much longer. It is giving nearly identical star test images inside and outside focus. Star images are very tight to where it easily splits Castor and has improved even more with the last test. I am still awaiting clear skies to evaluate the last 15 minute correction session.



Jim, Castor is a whopping 5 arc seconds apart these days -- hardly a "test" for a 9.25 inch aperture. If you're testing the theoretical limit of your 9.25 inch objective, then the distance ten times smaller (i.e. 0.5 arc seconds) may present a real challenege. Find a 0.5 arc second double in the Almanac and, on a good night, see how close the scope comes to its theoretical limit.

One thins is certain: your objective should be able to cleanly separate 1 arc second doubles, i.e. stars five times closer than Castor on any average night.

Even way back in the 1960s and 1970s, Castor was a tighter pair, separated by 1.8 arc seconds, which was a good test for a 3-inch objective, but certainly never for a 9.25
inch lens!

Reagrds,
Mladen


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kfrederick
Carpal Tunnel


Reged: 02/01/08

Re: 9.25 inch refractor project new [Re: MKV]
      #5791865 - 04/11/13 07:51 AM

http://www.windows2universe.org/our_solar_system/moons_table.html Jim you might be able to see some of Jupiter other moons . Congrats

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Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: 9.25 inch refractor project new [Re: kfrederick]
      #5791937 - 04/11/13 08:54 AM

Finding atmospheric conditions where .5 arc second rez is possible, is ludicrous where there's a lot of weather related changes- my 2 cents.
M.


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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project new [Re: Mark Harry]
      #5792238 - 04/11/13 12:14 PM

When I mentioned Castor as being EASILY separated with this objective , it was done with not the best seeing. It was done with the objective still in the process of being figured which it still is but indicates it is going in the right direction. Once I get to where the star is a point with 2 or so diffraction rings around that point like in my six inch will I consider it done. It is still inching towards that moment - more work to be done ! The weather up here is the clincher as it generally is bad seeing.

Edited by jimegger (04/11/13 12:16 PM)


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saemark30
Pooh-Bah


Reged: 02/21/12

Re: 9.25 inch refractor project [Re: jimegger]
      #5792241 - 04/11/13 12:15 PM

Did you start with pregenerated curves on the blanks Jim?
I gather you did all the grinding and figuring by hand.
If so, you deserve an extra round of applause.


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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project [Re: saemark30]
      #5792253 - 04/11/13 12:19 PM

I tried generating curves myself with a diamond tool but chipped the blank (crown) so I ended up doing it all by hand. I would certainly recommend getting the supplier to generate curves as it will save a ton of time grinding. If you are using glass tooling then you need them made with matching curves as well of course.

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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: 9.25 inch refractor project [Re: jimegger]
      #5803838 - 04/17/13 01:27 AM Attachment (36 downloads)

Okay Mike, here's your lunar limb shot taken with a hand held Canon digital camera through a Meade 50 mm wide angle 2 inch eyepiece when the sky is still somewhat light in the evening.

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Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: 9.25 inch refractor project new [Re: jimegger]
      #5804012 - 04/17/13 07:07 AM

I'd say that's pretty darn good!!! Moon's so bright there should be a bit of color anyhow. Doesn't look objectionable, and usually a small camera's shot misses a lot of what can actually be seen.
(My 2 cents)
M.


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