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john@dps
member


Reged: 02/06/13

Loc: Granada Hills, CA
C6R lens upgrade new
      #5738501 - 03/17/13 12:22 PM

Does anyone know if the Istar 150 R30 lens is a bolt in fit for the C6R tube i have? I cant afford a new scope but the next best thing is to just get a better lens. I think mine is just an average one, and would like to upgrade however I have no desire to make a new telescope and would like to plug and play. Istar gives its specs but i have no specs on the C6R other than 150mm lens, to me that means it should bolt in right? I also have no tools to measure anything like 150mm to 190mm like Istars specs state. My real concern in the fit comes in the fact that the lens is around 900 dollars and if it wont fit my scope I will own a very expensive cup coaster. Thanks

John


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Rusted
member


Reged: 12/06/08

Re: C6R lens upgrade new [Re: john@dps]
      #5739328 - 03/17/13 06:25 PM

You ought to ask Istar directly.

The Istar cell would need a matching thread to fit the Celestron tube.
Assuming, of course, that your C6R cell fits on an external thread as does my older CR150.
Does your C6R cell thread on? Or is it bolted?
My CR150 is completely inaccessible for accurate measurement right now. (snow storm)

The Istar illustrations on their website do not show the method of fixing to the telescope tube.
Their website shows 140mm OD tubing. This might fit inside their cells.
Which might be quite a good sliding fit on the Celestron tubing.

It would seem a shame if Istar misses the chance to offer upgrade objectives for the popular Celestron 6" refractors.
It seems such an obvious market for them.
It would probably be very unlikely that their glass precisely fits the Celestron cells.
Which might have been an alternative upgrade route for you.


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herrointment
Post Laureate
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Reged: 03/12/11

Loc: North of Hwy. 64
Re: C6R lens upgrade new [Re: Rusted]
      #5739485 - 03/17/13 07:37 PM

For a couple grand APM is offering a replacement objective made from ED glass. OPT carries it.

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john@dps
member


Reged: 02/06/13

Loc: Granada Hills, CA
Re: C6R lens upgrade new [Re: herrointment]
      #5739547 - 03/17/13 08:07 PM

I've sent an email to Istar and am waiting a reply, though I'm not expecting Istar to be C6R experts. I will check into the apm I didn't know about that one.

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dan_h
Carpal Tunnel


Reged: 12/10/07

Re: C6R lens upgrade new [Re: Rusted]
      #5739728 - 03/17/13 09:56 PM

Quote:

It would seem a shame if Istar misses the chance to offer upgrade objectives for the popular Celestron 6" refractors.
It seems such an obvious market for them.




The reason the Celestrons 6" f8 is so popular is because they are a pretty decent achromat. Istar would have to offer something significant at a really fair price to convince a lot of Celestron owners that they would get their money's worth in an upgrade. When an upgrade is priced well above the current market value of a scope, it can loose its appeal real fast.

Sure, a $1500 6" ED lens set will sell. A $1000 6" fancy achromat will sit on the shelves.

Just my opinion.

dan


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bremms
Carpal Tunnel
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Reged: 08/31/12

Loc: SC
Re: C6R lens upgrade new [Re: dan_h]
      #5739920 - 03/18/13 12:38 AM

An R30 would be a little better since it has a less CA, but still like 6" F10.4 tSwapping out a 6" F8 Achromat... no the poly chromatic Strehl is not good at F10.4 or evenF12.

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bremms
Carpal Tunnel
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Reged: 08/31/12

Loc: SC
Re: C6R lens upgrade new [Re: bremms]
      #5739921 - 03/18/13 12:43 AM

The Istar lens comes without a tube flange (counter cell) so you could machine one to fit. The Istar R30 lens is VERY heavy. Probably double the weight of the C6r lens.

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john@dps
member


Reged: 02/06/13

Loc: Granada Hills, CA
Re: C6R lens upgrade new [Re: bremms]
      #5740579 - 03/18/13 12:04 PM

I didnt know that about the weight. Right now im using an etx 90 to counter balance the C6R so I dont have to sit on the ground to view up. Istar just emailed me back and said that they are making adapters as we speak for the C6R to plug and play. They said as soon as they are done with the testing and fitting we will be able to buy them, which from the email sounded like it wont be long since they all ready have prototypes.

John


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bremms
Carpal Tunnel
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Reged: 08/31/12

Loc: SC
Re: C6R lens upgrade new [Re: john@dps]
      #5740684 - 03/18/13 01:04 PM

The R30 should be an upgrade, but will still have a good bit of color. At 6" I find achromats have noticeable color at F15.
For me, I was used to using longer focus reflectors, so any color is noticeable to me. My 4" F15 Jaegers does have very little, but it can still be seen. My 5" D&G has color too.


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john@dps
member


Reged: 02/06/13

Loc: Granada Hills, CA
Re: C6R lens upgrade new [Re: bremms]
      #5740721 - 03/18/13 01:30 PM

The color has never bothered me much. I spend most of my time with DSO's and trying and trying to see nebula's from my light poluted back yard in LA. The lens upgrade for me is to get the best view I can get without having an APO. My lens I think is just average because Ive looked through some scopes that had better pin points than mine and most of them werent APO's, they were just good quality scopes and I figure I have a tube why cant I just get a better lens.

Though on a side note I do understand that it is not in the overall best interest of the industry to go around selling just lens, because if one could buy just ed glass for there scope at any give store, why would one buy a new telescope other than apeture or change of style?

John

Edited by john@dps (03/18/13 01:40 PM)


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KerryR
Post Laureate
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Reged: 12/05/07

Loc: SW Michigan
Re: C6R lens upgrade new [Re: john@dps]
      #5741848 - 03/18/13 09:50 PM

That's kind of exciting news that Istar is going to make plug an play adapters for the C6R.

I have a Chromacor Null that I'd like to pair with a better objective than the stock objective in my C6-R. I looked at Istar a while back, but wasn't confident I'd be able to come up with a suitable interface for the cell. Too bad, though, about the weight; the C6-R is already kind of top heavy...


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Rusted
member


Reged: 12/06/08

Re: C6R lens upgrade new [Re: john@dps]
      #5742514 - 03/19/13 09:49 AM Attachment (19 downloads)

Quote:

The color has never bothered me much. I spend most of my time with DSO's and trying and trying to see nebula's from my light poluted back yard in LA. The lens upgrade for me is to get the best view I can get without having an APO. My lens I think is just average because Ive looked through some scopes that had better pin points than mine and most of them werent APO's, they were just good quality scopes and I figure I have a tube why cant I just get a better lens.

John




I wonder how much you would really gain from a "better" lens on DSOs under heavy light pollution?
A good filter may actually be more useful.
With a new lens you might only gain on planetary/lunar detail when the seeing permits.
A new lens may be more "sexy" but I'd invest first in a taller, rock solid base for your mounting.
So you can sit perfectly comfortably while viewing the zenith through a good star diagonal.
Then use an adjustable height observing chair.
Or lean, facing a stepladder, to view at lower altitudes.
A rock solid view is a better view. Comfort makes a huge difference to how much you can actually see.

Work on maximising contrast.
If the nearby moon or a planet shows a glow long before you get them in the field of view then your contrast can be improved.
The dewshield is usually far too short on most commercial refractors and they often have poor light absorbing paint.
Particularly at glancing angles.
This just funnels stray light into your field of view.
Your dewshield wants to be about 2.5-3 times aperture and preferably much larger than the aperture.
I wrap stiff, black plastic or black foam around the existing dewshield.
Both types are just taped into a tube and held in place by friction.

Sensitivity to chromatic aberration is a personal and often age-related factor.
I find it is also highly seeing related.
Seeing false colour is not a competitive sport.


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rboeAdministrator

*****

Reged: 03/16/02

Loc: Phx, AZ
Re: C6R lens upgrade new [Re: Rusted]
      #5742559 - 03/19/13 10:13 AM

A light haze removed all false colour that I could detect on Jupiter using my SS 127mm. Alas; not exactly the optimal solution.

After all the money and time spent on my 127 I'm both seduced by the 152 and unwilling to part with the 127.

Nice setup there Rusty.


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john@dps
member


Reged: 02/06/13

Loc: Granada Hills, CA
Re: C6R lens upgrade new [Re: rboe]
      #5742589 - 03/19/13 10:28 AM Attachment (23 downloads)

Rusted, its interesting that you talk about seeing glow before you get to an object and i can see alot. I thought that was normal for scopes. I can see brite dso's even before i get to them, so thats not right I take it. I have the stock C6R dew sheild that I thought was ok, so I should get a longer shield? This is the first time I've heard anyone take about seeing glow before seeing the object, the moon and jupiter are really bad in my scope, I can see where they are way before I get to them.

John

Edited by john@dps (03/19/13 10:33 AM)


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herrointment
Post Laureate
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Reged: 03/12/11

Loc: North of Hwy. 64
Re: C6R lens upgrade new [Re: john@dps]
      #5742675 - 03/19/13 11:08 AM

That dew shield is a boat anchor. I get glow prior to bright objects also, and he's spot on about changing that out. Foam works great.

Fun looking set up you've got there.

Ron, someday I'll build my tapered tube 127....but the other six scopes all want attention and I don't think they are going to like the 10" F8 I might be bringing home .


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herrointment
Post Laureate
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Reged: 03/12/11

Loc: North of Hwy. 64
Re: C6R lens upgrade [Re: herrointment]
      #5742688 - 03/19/13 11:17 AM

Stupid question time, John.

Have you checked collimation?

I ask because my C150, which had been shortened by a previous owner, needed a serious filing job to get the focuser in the right position.


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john@dps
member


Reged: 02/06/13

Loc: Granada Hills, CA
Re: C6R lens upgrade [Re: herrointment]
      #5742833 - 03/19/13 12:24 PM

Im in the process of trying to get a chelshire I beleive they call it, and find or borrow a laser to check the JMI focuser

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buddyjesus
Carpal Tunnel
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Reged: 07/07/10

Loc: Davison, Michigan
Re: C6R lens upgrade [Re: john@dps]
      #5742901 - 03/19/13 12:59 PM

a collimation was necessary on my scope and it greatly reduced my soft focus problems that I thought was due to secondary spectrum. good advice above.

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plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: C6R lens upgrade [Re: buddyjesus]
      #5743433 - 03/19/13 04:51 PM

Here's an older article that might be useful.

web page


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Jim Curry
Pooh-Bah
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Reged: 10/29/07

Loc: STL
Re: C6R lens upgrade [Re: plyscope]
      #5743987 - 03/19/13 08:56 PM

John
I have both 4" & 6" f/12 Istar lenses. They both star test at 1/6 wave and are advertised at. 93 strehl. The f/8 at. 90. If that's better than your current lens it makes sense to make the upgrade. Assume Color to be the same.
Jim


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