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Celestron C6R Lens Upgrade

Started by klawson, 10/22/2018 08:49PM
Posted 10/22/2018 08:49PM Opening Post
Hi All,

Yes, I have been tinkering again. Love retirement! Anyway, working with Ales over at Istar Optical, I came up with an adapter that will allow the owners of the Celestron C6R (w/adjustable cell) the option of upgrading to an Istar 150mm F/8 R35 lens or standard Istar 150mm F/8 achromat. Got a lens not performing well? This may be an option for you. This CNC machined adapter is a composite of ABS plastic and MDF so as to not add more weight to the front heavy C6R. The use of this mod only requires a change of in focus position of about 3/8" and installs in about minute. The lens cell adjustability is maintained. Send me a PM if interested in the adapter.

Hope to get some photos and do a lens comparison soon.

Keith (Scopejunkie)

Attached Image:

klawson's attachment for post 159542

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 10/23/2018 08:14PM #1
Adapter Pic.

Attached Image:

klawson's attachment for post 159556

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 10/26/2018 12:56AM #2
Walking a tightrope? Nah! Made some extension arms for the lens adapter so I could test an F/10 objective with an F/8 telescope.

Keith (Scopejunkie)

Attached Image:

klawson's attachment for post 159589

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 10/27/2018 08:18PM | Edited 10/28/2018 02:17AM #3
All,

Here is the full story: I own a Celestron C6-R refractor and I had wondered what it would be like to have an Istar R35 F/8 lens in place of the standard C6-R F/8 achromat. Without the proper information on Istar's cell design this just remained an "idea." To scratch an itch, I finally contacted Ales at Istar and he kindly sent me the Istar 150 mm lens cell information. With this information I started my design of an adapter plate so I could swap out the C6-R lens for a Istar R35 lens.

After designing the adapter plate I asked Ales if he could send me a lens cell from one of their 150mm lenses so that after I had produced the adapter I could do a full fit check to see if what I had made worked. Ales graciously sent me an older 150mm standard F/10 achromat so I could perform my fit check since the original Istar cell design had not changed.

Everything worked.  I was a happy camper. Being the curious ATM that I am I decided to clean and check this lens for Ales and test it (yes, Ales knew what I was doing). I rigged up some extensions to extend my newly designed cell adapter from the C6-R and took a look at the night sky with the Istar F/10 lens. Using a 250 LPI etched glass ronchi grating, at only two bands, revealed that the lens had a spherical correction better than 1/8th wave looking at both sides of focus. The lens also has a good clean edge. The star test was quite good. The star test agreed well with the ronchi test. Much better than 1/6th wave overall correction (according to Suiter's book) with smooth surfaces (more like 1/7th). The lens passes the "two ring" star test.
 
Even though the seeing was "average" I could easily see the small polar cap of Mars (12.4 arc sec) with full surface markings at 150x. Though this was not a "high power" night, I ran the magnification up to 375x (4mm Ortho). I was quite surprised with the results. The planet remained detailed and crisp despite the seeing effects. I did get a good view of Saturn at 150x revealing all the usual details before it sank too low. I am wondering what this lens will do on a good night! Clean split Pi Aql at 150x. Reconfirmed at 215x revealing perfectly round airy disks. Also clean split 10 Aries at 150x. You can only do this with very tight star images.

This is without a doubt an optic that seems to "look past" the seeing allowing a lot of detail to be seen. The testing continues... After over 40 years of owning and making telescopes, I have owned only a few optics with this ability. Instead of sending this lens back, after confirming my adapter fit-up, I asked if I could buy it. It looks like Istar quality is consistent. My previous Istar 8" F/8.8 (2010) was a good lens also.

The pic is a simulation of what I was seeing at the eyepiece.

Time to purchase some new  "stuff" for a fall/winter refractor build...

Keith (Scopejunkie)

Attached Image:

klawson's attachment for post 159640

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 10/31/2018 06:20AM #4
Putting the 150mm Istar into an OTA. ATM juices flowing!

Keith (Scopejunkie)

Attached Image:

klawson's attachment for post 159823

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 11/01/2018 06:23AM | Edited 11/01/2018 06:24AM #5
New countercell finished and installed. Dewshield mounts are next.

Attached Image:

klawson's attachment for post 159887

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 11/02/2018 02:14AM #6
Dew shield installed.

Attached Image:

klawson's attachment for post 159982

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 11/03/2018 03:15AM #7
Up and operationalgrin

Attached Image:

klawson's attachment for post 160018

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet




 
Posted 11/03/2018 03:57PM #8
Any baffles in there?

Never built a refractor using that kind of tubing....what did it end up weighing?

20" MidnighTelescopes f/5
8" f/16 Muffoletto Achro
Meade 6" AR6 f/8.0 Achro
Celestron C11
Parallax PI250 10" F/5 Newt
Vixen FL102S,NA140SS,R200SS
80mm Stellarvue Nighthawk with WO APOupgrade lens, 90mm f/16.67 Parallax Achro
LXD75/LX200, Mini-tower, GP-DX, CG5 ASGT, LXD650, GM-8, G11, GM-100, GM-150EX, GM-200 and a Gemini G40
4" portable AP convertable 44" or 70" pier
Stellarvue M7 Alt-Az, TSL7 Pier/Tripod
12.5" f/5 MidnighTelescopes DOB Swayze optics
Monroe GA
Posted 11/03/2018 08:56PM | Edited 11/03/2018 09:07PM #9
Hi Greg,

No baffles yet. The dew shield and main tube just have flat black for now. I will make them soon. I had thought that the ota was lighter than the Celestron C6-R but it's about 5lbs heavier. The tubing is not your standard "sonotubing." The tubes are heavy duty mailing tubes from Yazoo Mills. The tubing wall thickness is about 1/4". These tubes are quite precise and very straight. I have made a couple of 8" F/12 refractors using this tubing.

Keith (Scopejunkie)

Attached Image:

klawson's attachment for post 160059

Scopejunkie


40 year old restored C14 with recirculating cooling w/Skywatcher DOB GOTO Conversion (CPC14)

Synscan DOB mounted Sky-Watcher Evostar 150mm/1200mm ED Refractor

"Rescued" Craig's List Orion 120mm/1000mm Refractor


USAF Vet