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Celestron Luminos 2" 2.5x telecentric barlow

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#1 russell23

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Posted 16 January 2013 - 07:40 PM

I just noticed that Celestron has come out with a 2" 2.5x telecentric barlow:

http://www.celestron...arlow-lens.html

What is curious about this one is that it's weight is listed as only 11 oz - about half the weight of the 2" powermates and 2" 2x ES telecentric barlow.

Anybody tried one of these yet?

Dave

#2 Starman1

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Posted 16 January 2013 - 08:31 PM

Aluminum barrel instead of brass? Thin-walled upper?
And could the weight listed simply be wrong?
11oz seems awfully light for a 2" 4-element design. That's almost 3 ounces lighter than the 3-element AstroTech 2" barlow.
I bet it was meant to be 21 ounces.

#3 russell23

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Posted 16 January 2013 - 09:30 PM

Aluminum barrel instead of brass? Thin-walled upper?
And could the weight listed simply be wrong?
11oz seems awfully light for a 2" 4-element design. That's almost 3 ounces lighter than the 3-element AstroTech 2" barlow.
I bet it was meant to be 21 ounces.


That was my thinking. The ES 2" 2x weighs 23oz.

Dave

#4 Starman81

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Posted 17 January 2013 - 12:28 AM

Dave, I didn't see telecentric mentioned anywhere on Celestron's webpage. Did you assume that from teh 4-element design?

#5 russell23

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Posted 17 January 2013 - 10:09 AM

Dave, I didn't see telecentric mentioned anywhere on Celestron's webpage. Did you assume that from teh 4-element design?


I inferred that it is telecentric from the 4-element design, the description reference to it giving a flatter field, and the smaller clear aperature of 28mm.

Is there another 4 element barlow design that is not telecentric? Perhaps I'm wrong about it being telecentric, but if so then it seems kind of silly to have a 4 element barlow that doesn't give the benefits of the telecentric design.

Dave

#6 eklf

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Posted 17 January 2013 - 10:18 AM

Is there another 4 element barlow design that is not telecentric?


Orion used to sell a 5-element barlow (called highlight)that was not telecentric (atleast, I dont think it was telecentric. At one point I had considered that unit, but found no mention of "telecentric" or absence of ER increase or absence of vignetting. In the end I decided not to buy it, so I dont know for sure).

#7 Manish

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Posted 17 January 2013 - 01:29 PM

>>this one is that it's weight is listed as only 11 oz

This barlow is indeed a lightweight. On our calibrated weighing scale, it weighs in at all of 10.2oz with the 1.25" adapter, and just 7.3oz without the adapter (weighed without the 2 plastic end caps)!

Regards,
Manish
www.AgenaAstro.com

#8 russell23

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Posted 17 January 2013 - 01:55 PM

>>this one is that it's weight is listed as only 11 oz

This barlow is indeed a lightweight. On our calibrated weighing scale, it weighs in at all of 10.2oz with the 1.25" adapter, and just 7.3oz without the adapter (weighed without the 2 plastic end caps)!

Regards,
Manish
www.AgenaAstro.com


Wow - that is light. I might have a use for that one. Thanks Manish. Any idea if it is a telecentric? Have you had a chance to test one out?

Thanks!

Dave

#9 Starman81

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Posted 20 January 2013 - 09:46 AM

Yes, super light indeed. Our sponsor also has it up now, with a nice picture . I always liked metallic look of the Luminos and Axioms and I'm a sucker for barlows, might just have to try one out. It gets me some nice usable powers, 136x with the 22T4 and 231x with the 13 Ethos...

#10 herrointment

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Posted 20 January 2013 - 01:55 PM

A quick heads-up if I may. I own or have owned both the Axiom LX and Luminos EPs in various focal lengths. IMO the Luminos line is nowhere close to being in the same league as the Axiom LX. Appears Celestron changed manufactures for the Luminos line.

I've looked at this barlow but the name engraved on the side frightened me off.

#11 Starman81

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Posted 20 January 2013 - 02:25 PM

A quick heads-up if I may. I own or have owned both the Axiom LX and Luminos EPs in various focal lengths. IMO the Luminos line is nowhere close to being in the same league as the Axiom LX. Appears Celestron changed manufactures for the Luminos line.

I've looked at this barlow but the name engraved on the side frightened me off.


Jim, I remember reading your thread about the Luminos line, something about EOF brightening IIRC. It scared me off of the 19mm which I was looking forward to trying with its 20mm of ER. Hopefully the barlow will not share that same characteristic.

#12 russell23

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Posted 20 January 2013 - 06:50 PM

A quick heads-up if I may. I own or have owned both the Axiom LX and Luminos EPs in various focal lengths. IMO the Luminos line is nowhere close to being in the same league as the Axiom LX. Appears Celestron changed manufactures for the Luminos line.

I've looked at this barlow but the name engraved on the side frightened me off.


Jim, I remember reading your thread about the Luminos line, something about EOF brightening IIRC. It scared me off of the 19mm which I was looking forward to trying with its 20mm of ER. Hopefully the barlow will not share that same characteristic.


Yes - I saw EOFB in the 19mm Luminos - which was very frustrating because I otherwise liked the view. Same with the 12mm Celestron X-cel LX. I haven't been all that impressed with any Celestron eyepieces other than the old silvertop plossls.

Dave

#13 Magellan

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Posted 10 February 2014 - 10:52 AM

I was looking at getting one for planetary imaging using my DSLR and F3.9 Newt and MPCC. Right now I am doing eyepiece projection but the camera sits a foot out from the tube, not good for balance and great for grinding gears, the 2" barlow would keep the camera closer to the focuser.

#14 Starman81

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Posted 19 January 2015 - 04:16 PM

Yes, super light indeed. Our sponsor also has it up now, with a nice picture . I always liked metallic look of the Luminos and Axioms and I'm a sucker for barlows, might just have to try one out. It gets me some nice usable powers, 136x with the 22T4 and 231x with the 13 Ethos...

 

It has been about 2 years since I considered this barlow and knowing that I would still like to use it with the 13 and the 10 Ethos, I snagged the one on AM yesterday.

 

I don't mind barlowing Ethoi at all, not one bit, especially when it would save me $1K in equivalent Ethoi. I rather use a 2.5x 2" instead of my 2.5x 1.25" PM to keep the moment arm small and for greater stability. Jury is out on the optical performance until I get this one in. 



#15 russell23

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Posted 19 January 2015 - 05:40 PM

 

Yes, super light indeed. Our sponsor also has it up now, with a nice picture . I always liked metallic look of the Luminos and Axioms and I'm a sucker for barlows, might just have to try one out. It gets me some nice usable powers, 136x with the 22T4 and 231x with the 13 Ethos...

 

It has been about 2 years since I considered this barlow and knowing that I would still like to use it with the 13 and the 10 Ethos, I snagged the one on AM yesterday.

 

I don't mind barlowing Ethoi at all, not one bit, especially when it would save me $1K in equivalent Ethoi. I rather use a 2.5x 2" instead of my 2.5x 1.25" PM to keep the moment arm small and for greater stability. Jury is out on the optical performance until I get this one in. 

 

I saw that one listed but decided to pass.  Price was very good.  I am very much looking forward to your thoughts about the quality of this one.  If its performance is good it would be an excellent one to pair with my 28mm ES68.

 

Dave



#16 CeleNoptic

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Posted 25 January 2015 - 08:08 PM

So, what about the OP question, has anybody tried this Barlow? Is it any good?



#17 Starman81

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Posted 25 January 2015 - 10:34 PM

I did take receipt of it. Haven't tried it out with all the clouds recently, even got skunked for the triple transit :(.

 

I can confirm that it is very lightweight for being a 4-element 2" barlow. 11oz sounds right but no scale on hand to confirm. Comparable to the Antares 1.6x in weight (9 oz), except you get a 1.25" adapter, which adds that couple ounces, I'm sure. 4-element but no claims of 'telecentricity' anywhere on the box. Celestron does claim it is 'apochromatic'. 

 

Did the bright wall test with the 13 and 10 Ethos and found the preliminary findings to be good with regards to exit pupil behavior but won't really know until the barlow + eyepiece combo is plugged in a scope. 

 

Clear aperture is listed as 28mm, but I tried it with the 22T4 Nagler (31.1mm field stop) and could not see vignetting. I guess it was there but slight? Anyways, I don't have plans to use it with long f/l eyepieces. 



#18 smeyer8015

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Posted 25 January 2015 - 11:54 PM

I just received mine last Monday.

 

Had a short chance to try it out Wednesday night

 

It is definitely light and apochromatic. no hint of chromatic aberration at all.

 

Decided to use the 18mm X-Cel LX in it (282x), it was tricky to keep eye position, but looking at M42 I could discern 4 stars at the center in stead of the usual 3.

 

Have not had a chance to give it a full workout yet.

 

Scott

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Edited by smeyer8015, 25 January 2015 - 11:59 PM.


#19 CeleNoptic

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Posted 31 January 2015 - 12:26 AM

Folks, thanks for the preliminary info. Have you had a chance to try it in the field?

 

 

 

Decided to use the 18mm X-Cel LX in it (282x), it was tricky to keep eye position

 

 

Scott, does it mean that the Barlow elongates eye relief relatively to what you used to have in your 18mm X-Cel LX without Barlow? If so, than it's definitely not telecentric.



#20 Starman81

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Posted 02 February 2015 - 12:59 AM

Folks, thanks for the preliminary info. Have you had a chance to try it in the field?

 

 

No chances yet to try in the field yet. Might try using it with the EON 80mm refractor to push the power on lunar/planetary to get an idea on how this barlow fares. Could compare it to my TV 2.5x Powermate. 



#21 CeleNoptic

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Posted 14 February 2015 - 06:41 PM

bump.



#22 Starman81

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Posted 14 February 2015 - 07:31 PM

bump.

 

My Pentax XO 5 came in and that bumped this barlow off the priority list for testing :(. Couple that with the issues I was having with my AT Voyager mount put me out of commission for some time, but the weather was equally culpable.

 

To add to the excuses, today and tomorrow are the coldest days of the winter here this year (so far). Look at this... -37 °F 'Real Feel' tonight! 

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