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5mm X-cel LX, keep or replace?

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#1 precaud

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Posted 06 February 2013 - 07:50 PM

I bought a 5mm Celestron X-cel LX last month, and haven't been thrilled with it. I have the 7mm and 9mm and like them both, they hold up well in an F/5 dob. Had a chance to use it in a friend's F/7 Discovery dob last night and his unsolicited comment was "muddy".

I can return it for replacement or refund, and have the RMA. Without knowing whether this is just the nature of the beast or I just got a lemon, I'm uncertain what to do.

Should I give another one a try, or go with something else? Anyone have experience and/or thoughts about this particular LX? Would appreciate your input.

#2 Kon Dealer

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Posted 07 February 2013 - 04:46 AM

I too have the LX 9 and 7mM and like then- apart from the fact the twist-up cap gets very stiff when it is cold.
I already have a 5mM AT Paradigm EP and find this very good.
At least down to f/6- couldn't comment on whether it holds up at f/5.

#3 Ernest_SPB

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Posted 07 February 2013 - 06:02 AM

5mm X-Cel LX (as well as 4.5 HD-60) is a very good EP with good image quality over whole field of view and convenient eye relief.

In most cases when I hear about bad image quality of short focal EP I recommend to collimate telescope - looking for source of the imperfectness in telescope rather then in EP.

#4 Don Taylor

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Posted 07 February 2013 - 07:06 AM

I was initially disappointed with my es 4.7 but really, the problem turned out to be seeing. High magnification reveals poor seeing - what may have been acceptable with longer f.l. Eyepieces is perceived as poor image quality at higher magnifications.

Once I had a night of steady air it's performance turned out to be quite good. How was the seeing on the nights you used the 5mm?

#5 precaud

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Posted 07 February 2013 - 08:24 AM

Seeing was very good that night, best yet this year... on previous nights I compared the 5mm LX to a barlowed 10mm plossl and it was clearly the worse. So I knew something was wrong and got another observer's opinion, on a better rig than mine. There is no question something is amiss with this particular EP... the question is whether to take a refund and get something else, or exchange it for another one. I'm inclined to do the latter, because I like this EP series. But I also know, every example in a product line is not uniformly good.

#6 REC

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Posted 07 February 2013 - 09:47 AM

I have the 9mm version and it works pretty well....from there I go to a ES 6.7 and that works very well. Wanted a little more power in my 80mm so bought the AT-5mm. It's a nicely made EP, but can't use it most of the time. Either sky problems or just too much power exit pupil for my 60yr. old eyes.

I'm probably going to sell it and stay with a 6mm for max power.

Bob

#7 BillP

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Posted 07 February 2013 - 09:56 AM

A number of recent posts of people discussing the X-Cel LX and the AT Paradigms generally say that the Paradigms give a cleaner view. So perhaps you should try the 5mm of that one instead. (of course there are also other boards where discussions on the two have gone the other way)

As far as the "muddy" comment from your friend...was there another eyepiece being used that evening to compare against to put that comment in perspective? If there were no other 5mm eyepieces being compared, then IMO fairly well impossible to make a conclusion that an eyepiece was "muddy". Instead would say the system+sky was producing a muddy view.

#8 precaud

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Posted 07 February 2013 - 10:04 AM

Bill, my understanding is that they are the same glass in different packages. Is that not the case? (My 9mm is actually the Meade variant).

Yes, we were moving the 5mmm and 7mm LX and a 7mm Nagler between the two dobs. The 7mm held up pretty well in the compare.

#9 russell23

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Posted 07 February 2013 - 10:17 AM

Bill, my understanding is that they are the same glass in different packages. Is that not the case? (My 9mm is actually the Meade variant).


The Celestron X-cel LX and the Meade HD-60 are the same glass in a different packaging, but the Astrotech Paradigm's are a different design. IMO the Paradigm gives the superior performance. I have really been shocked at just how good the transmission seems to be in the Paradigm's. Last night at one point I was looking at the Orion nebula with my 20mm XW (40x) and then I switched to the 15mm Paradigm (53x) and the nebula actually seemed richer and brighter. I also noticed the same outcome with the 15mm Paradigm against my 12.8mm Zeiss (63x).

Keep in mind I've only used the 15mm Paradigm for deep sky up to this point. I wouldn't want anything I say here extrapolated to Lunar/Planetary observations.

Dave

#10 precaud

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Posted 07 February 2013 - 10:22 AM

Thanks Dave. Perhaps someone with the 5mm Paradigm will weigh in...

#11 csrlice12

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Posted 07 February 2013 - 10:54 AM

I bought a 5mm Celestron X-cel LX last month, and haven't been thrilled with it. I have the 7mm and 9mm and like them both, they hold up well in an F/5 dob. Had a chance to use it in a friend's F/7 Discovery dob last night and his unsolicited comment was "muddy".

I can return it for replacement or refund, and have the RMA. Without knowing whether this is just the nature of the beast or I just got a lemon, I'm uncertain what to do.

Should I give another one a try, or go with something else? Anyone have experience and/or thoughts about this particular LX? Would appreciate your input.


Truthfully, I'm not surprized the view was a little fuzzy with a 5mm eyepiece in an f7 scope as you are under 1mm exit pupil. Unless the viewing was fantastic, you just can't push the mag like that. I've not read any "bad" reviews of these eyepieces, many have found them an acceptable alternative to premium eyepieces. They will suffer some off-axis abberations, but usually only in the outer edges of the FOV.

#12 REC

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Posted 07 February 2013 - 11:31 AM

Yes I agree, the exit pupil is just a little to small for me with the 5mm in my f/7 scope. Starts to bring out the floaters and other defects in my eyes.

Bob

#13 BillP

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Posted 07 February 2013 - 11:37 AM

Truthfully, I'm not surprized the view was a little fuzzy with a 5mm eyepiece in an f7 scope as you are under 1mm exit pupil. Unless the viewing was fantastic, you just can't push the mag like that.


Good point...and agreed. Since the OP stated it was a Discovery scope and f/7, then likely their 8" model. In that case a 5mm eyepiece in an 8" f/7 scope would produce 284x...so a bit on the high end to expect crystal clarity (plus compound on that the potential eye issues given the low exit pupil).

#14 precaud

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Posted 07 February 2013 - 12:01 PM

Hmmm... I think the wise thing to do at this point is return it and and do some more research. I can always barlow up a 10mm to cover it in the meantime. Thanks everyone for the great input.

BTW, the guy who has the 8" Discovery has 5mm EP's that do well in it. The 5mm came into the mix to equalize the difference in the focal lengths of the two scopes when comparing the 7mm EP's. With 40 years more experience than I have, when he voices an observation, I listen... :)

#15 Scanning4Comets

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Posted 07 February 2013 - 02:30 PM

The Celestron X-cel LX and the Meade HD-60 are the same glass in a different packaging, but the Astrotech Paradigm's are a different design. IMO the Paradigm gives the superior performance. I have really been shocked at just how good the transmission seems to be in the Paradigm's. Last night at one point I was looking at the Orion nebula with my 20mm XW (40x) and then I switched to the 15mm Paradigm (53x) and the nebula actually seemed richer and brighter. I also noticed the same outcome with the 15mm Paradigm against my 12.8mm Zeiss (63x).

Dave


Better than a Pentax XW or a Zeiss? I find that hard to believe. (Not saying I don't believe you Dave, I'm just saying that the glass in both the XW and the Ziess are far superior). Must have been conditions or something?

Good point...and agreed. Since the OP stated it was a Discovery scope and f/7, then likely their 8" model. In that case a 5mm eyepiece in an 8" f/7 scope would produce 284x...so a bit on the high end to expect crystal clarity (plus compound on that the potential eye issues given the low exit pupil).

--------------------
Bill


Good points Bill. Not only that, but one really needs to keep testing over several nights at different locations and different weather conditions. Jon Issacs also made some good points about this in saying that aberrations can be hidden in light polluted skies. One really needs to test in darker skies when stars and nebulae are much brighter and clearer for a full evaluation.

Hmmm... I think the wise thing to do at this point is return it and and do some more research. I can always barlow up a 10mm to cover it in the meantime. Thanks everyone for the great input.

BTW, the guy who has the 8" Discovery has 5mm EP's that do well in it. The 5mm came into the mix to equalize the difference in the focal lengths of the two scopes when comparing the 7mm EP's. With 40 years more experience than I have, when he voices an observation, I listen...


Prob had a dud then.

Cheers,

#16 precaud

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Posted 07 February 2013 - 02:49 PM

aberrations can be hidden in light polluted skies


I know some of you guys have to deal with that, because I visit cities near sea level from time to time and am always stunned by the poor air quality. But here in the mountains of northern New Mexico, air pollution is not a topic of concern...

#17 csrlice12

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Posted 07 February 2013 - 03:35 PM

Northern New Mexico. I know it's pretty desolate between Las Vegas and Taos.....and for your listening pleasure, there's the Taos Hummmmmmmm

#18 BillP

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Posted 07 February 2013 - 03:55 PM

The Celestron X-cel LX and the Meade HD-60 are the same glass in a different packaging, but the Astrotech Paradigm's are a different design. IMO the Paradigm gives the superior performance. I have really been shocked at just how good the transmission seems to be in the Paradigm's. Last night at one point I was looking at the Orion nebula with my 20mm XW (40x) and then I switched to the 15mm Paradigm (53x) and the nebula actually seemed richer and brighter. I also noticed the same outcome with the 15mm Paradigm against my 12.8mm Zeiss (63x).

Dave


Better than a Pentax XW or a Zeiss? I find that hard to believe. (Not saying I don't believe you Dave, I'm just saying that the glass in both the XW and the Ziess are far superior). Must have been conditions or something?


Well, a 15mm eyepiece will produce a 38% brighter image than a 12.8mm eyepiece. Given both of these will be in the 2mm exit pupil range for an f/7 scope, with the nice dark background from that exit pupil, easy to account for the "brighter and richer" view of the Paradigm due to the focal length difference alone. So even though theoretically the Zeiss or XW glass may be better than the AT glass, not going to overcome the 38% brightness advantage of the 15mm!

#19 precaud

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Posted 07 February 2013 - 04:35 PM

...and for your listening pleasure, there's the Taos Hummmmmmmm


LOL, I've heard of it, but never heard it. I'm in Santa Fe.

PS - we also confirmed that evening that my 25mm Sterling has issues... it's going back for exchange today too.






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