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First impression of the Lunt 102 ed

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#1 coutleef

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Posted 22 November 2012 - 09:54 PM

Greetings to all and happy Thanksgiving to all our American neighbours.

As promised, these are my first impressions on the new Lunt 102 ED f|7 refractor (that we can probably call a semi-apo). There is not that many evaluations of this scope (in fact there is none) but so keep in mind the following limitations of this evaluation:

1) I just had the scope today, so my opinion may change overtime.
2) I am new to the refractor word since buying the 80mm apo from ES this spring.
3) This evaluation was done on an evening of above average seeing but below average transparency
4) I was using a manual alt-az mount and not a motorized mount
5) I am not very knowledgeable in the field of refractor.
6) Forgive my less than optimal written English, English is not my native language.
7) I may have obtained a very good unit so others should give their evaluation.
With these caveats in mind, here is what I think of this scope.

So, is the Lunt 102 ED a good buy? In short, I am keeping mine. Is it perfect: no. For $742 I never expected it to be perfect. This is not a NP101, but i liked what I saw with it.

First of all, I will say that I used it with the Twilight II mount which is and excellent alt-az mount. Heavy enough that it is sturdy, but not too much so it is easily portable. It weighs 17 pounds and the movement is very smooth with brakes in both direction. But when your scope is well placed and everything is balanced, you can avoid using these brakes. The 102 is longer than the previous 80mm I owned but I can place the scope enough forward on the mount that viewing at the zenith is comfortable.

First, why purchase a 102mm when I had an excellent 80mm. I first bought the apo to complement two bigger scopes but soon realized I liked using refractors and wanted to use it by itself on some evenings, not only for the wide views but as a polyvalent scope also easy to set up. I also have to consider the cooling down time sometimes required here. In winter, my scopes go from 70 F to -30F. That could take at least two hours for my SCT to cool down. I wanted a scope with a little more aperture than the 3 inch apo that could still show wide fields when needed but would not take forever to cool down.

What is the difference between 3 and 4 inch refractors? Quite noticeable, especially on the moon and planets. I am a fan of star clusters and from the city, that 1 additional inch makes quite a difference from what I saw with the Lunt 102 ED. And since the 102 ED is a doublet, it is not heavy and will cool down rapidly. When I look at the two scopes, the 80mm is so small it looks like a toy while the 102mm looks like a telescope. Do not get me wrong, for many the 80mm is a superb little and very portable scope. But for my needs, I will keep the 102mm.
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First The steel case that it comes in is solid and sturdy. Not as well built as the one that came with the ES 80mm. Not too big and not too heavy but the case only contains the scope and there is no place for EPs or a diagonal or the finder. Explaining why it is small for a 102mm scope. The scope is bigger than a 3 inch but because of the sliding dew shield, it is not very long and is easy to transport. I still consider it a grab and go.

No instruction came with the scope. I figured how it worked but some instructions would have been nice. Building up this little refractor and understanding how it worked was fairly easy.

I noticed that one screw was missing on the focuser and I was disturbed by that. By looking at the scope with the dealer, we figured that it was a screw to help fix some accessories, so probably not that useful. So we wrote to the company to replace it.

I installed a Orion RACI and that was not easy. Not sure I used the appropriate shoe. I also installed a WO 2 inch dielectric diagonal.

The focuser is a very nice and smooth two-speed Crayford focuser with a locking screw. Really liked the ability of the focuser to get right to focus, easily and smoothly in a f/7 scope. The focuser holds very well my 40mm pentax when looking at the zenith. All in all, the focuser is very pleasant to use. The focuser can also be rotated which is a nice feature.

The beauty of this scope compared to the ES scope is the sliding dew shield. I found no paint defect on the tube or dewshield. The scope is quite short when the dew shield is retracted and it is very easy and smooth to slide out and in, and it can be fixed with a screw when fully extended. But I did not need that when looking at the zenith. Even if the scope is bigger than the 80mm scope, I found it was easy to balance the scope on the mount because it can be put quite forward on the mount. A metal screw-on cap closes the dewshield when not in use.

What about the optical performance: I first looked for color correction. This is not a triplet but a doublet with ED glass. Looked at the moon and really had difficulty finding any trace of chromatic aberration. Finally, I saw on and off a small rim of violet on the moon limb but I really had to look for it and concentrate to find it. So I looked at Jupiter with a moon and skyglow filter (which I always use with planets) and did not see any CA. When I took off the filter, there it was. A very slim rim of violet around Jupiter. Personally, I do not find it distracting and just forget about it while looking at the planet. It does not interfere with observation at all. I then looked at high magnification at Vega and the violet was there for sure. This is not an apo, but is perfect for my needs as a visual only scope.

I then performed a star test and was very satisfied. The scope was collimated out of the box at high magnification. In and out of focus on vega revealed that there was a slight amount of what I think was spherical aberration. Nothing unexpected really.

Then I used the scope on the moon and Jupiter. Could see several bands on Jupiter, and four satellites were clearly visible. A lot of details were seen on the moon (more than with the 3 inch). The views were spectacular and contrasty.
I then looked at several star clusters and was amazed at the difference one inch could make. This will be a nice scope to use at my dark site. Unfortunately, transparency was not very good and clouds rolled in. SO I had to stop my session.

I used my Pentax XW 30mm and 40mm to see how nice the wide fields were. Superb, with FOV of nearly 3.9 degrees with the 40mm with pinpoint stars all across the fov. . That little scope will makes a great companion on all counts with a big dob or a medium size SCT.

Tried to see if there was field curvature with that f|7 scope, which I thought should be present. But FC was not present with the 30 and 40mm Pentax, even when using my 20mm and 14mm Pentax. The field was flat, possibly because of the correction of the field curvature we should see with that refractor by the Pentax themselves?? Sorry for the Pentax detractors, but the Pentax EPs performed flawlessly with that scope.

I hope others will give their impression of that scope. It is not a high end scope, just a doublet with a case that is not as ‘sophisticated’ as the ES cases but it delivers the kind of views I wanted from a 4 inch semi-apo for visual purposes that remains very portable.

Clear skies

#2 rockethead26

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Posted 22 November 2012 - 11:04 PM

Sounds like a keeper! Nice report.

#3 GOLGO13

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Posted 23 November 2012 - 01:46 AM

Looking at the scope, I'm guessing it's pretty much the same as mine (with only a few minor differences). I think your impressions are similar as well. Mine is an Astro telescopes one. The same scope was packaged by other manufacturers (Stellavue, Orion, etc). It's manufactured by a Chinese company Kunming http://united-optics.com/

I think it's a great value telescope, but as you note, it's not perfect on the color correction. Still a wonderful scope and still grab and go!! Certainly it's a huge difference to the Celestron 102HD achromat I used to have. Not that the celestron was a bad scope, but even this lower color correcting ED glass makes a big difference.

#4 Jon Isaacs

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Posted 23 November 2012 - 02:41 AM

François:

Nice review.... sounds very much like the Astro-Tech 102ED... I suspect it is the same basic scope. My experience with the AT-102ED was very similar to yours. A good value in a compact package.

Jon

#5 coutleef

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Posted 23 November 2012 - 07:10 AM

François:

Nice review.... sounds very much like the Astro-Tech 102ED... I suspect it is the same basic scope. My experience with the AT-102ED was very similar to yours. A good value in a compact package.

Jon


dear Jon

I read several times your review if the AT scope and it convinced me of trying the lunt scope.

I almost entitled my thread: thanks to Jon Isaacs. But then it would not have helped those searching for a review on the lunt scopes!!

But thanks again. The scope is not perfect but corresponds exactly to what i need

#6 coutleef

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Posted 23 November 2012 - 07:12 AM

Looking at the scope, I'm guessing it's pretty much the same as mine (with only a few minor differences). I think your impressions are similar as well. Mine is an Astro telescopes one. The same scope was packaged by other manufacturers (Stellavue, Orion, etc). It's manufactured by a Chinese company Kunming http://united-optics.com/

I think it's a great value telescope, but as you note, it's not perfect on the color correction. Still a wonderful scope and still grab and go!! Certainly it's a huge difference to the Celestron 102HD achromat I used to have. Not that the celestron was a bad scope, but even this lower color correcting ED glass makes a big difference.


I am glad you like your scope. Definitely a keeper

#7 SteveG

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Posted 23 November 2012 - 02:17 PM

Sounds like a nice scope, but 17 lbs is heavy for a 102 doublet! My ED 120, with rings, 2" diagonal and 2" 27mm Pan is 17 lbs.

#8 coutleef

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Posted 23 November 2012 - 05:07 PM

Sounds like a nice scope, but 17 lbs is heavy for a 102 doublet! My ED 120, with rings, 2" diagonal and 2" 27mm Pan is 17 lbs.


dear Steve

i would not have purchased it if it was that heavy :lol:

that is the weigth of the alt az mount and tripod!!

the scope with diagonal and finder probably weighs around 11 pounds thus i would say that the tube plus rings weighs around 9 pounds.

sorry for the confusion

how is your ed 120 doing on vega and jupiter in terms of CA?

#9 stevew

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Posted 24 November 2012 - 07:34 PM

Nice report.Glad to hear you are enjoying your new scope. However if this is the same scope as the Orion Premium or the Astrotech, why is the Lunt so much cheaper?

#10 coutleef

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Posted 24 November 2012 - 08:52 PM

Nice report.Glad to hear you are enjoying your new scope. However if this is the same scope as the Orion Premium or the Astrotech, why is the Lunt so much cheaper?


i do not know. it does not come with a diagonal or finder.

the price may have come down because of the good deals on triplets. not long ago, the ES 102 triplet was sold with diagonal and finder for $1000. doublets should run for less

#11 Scott in NC

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Posted 24 November 2012 - 10:28 PM

Nice report, François--thanks for sharing it! I'm glad to hear that you're enjoying your new scope. :waytogo:

#12 Theoid

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Posted 01 October 2013 - 02:51 AM

Does it come with rings, and what type of mounting adapter did you purchase??

Thanks

#13 coutleef

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Posted 01 October 2013 - 07:34 AM

the scope comes with rings

#14 audioaficionado

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Posted 01 October 2013 - 09:56 PM

This Lunt 102mm ED will be my final refractor purchase unless I get blessed with a great deal on a TV NP101 in the unforeseeable future.

#15 coutleef

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Posted 02 October 2013 - 08:15 AM

these two scopes are in different leagues. you may be disappointed by the lunt if you expect the performance of the np101

#16 audioaficionado

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Posted 02 October 2013 - 03:48 PM

I'm not expecting to get the NP 101 unless I get a huge cash windfall. I wouldn't be disappointed in whichever one I get. It's obvious the 5x more expensive scope would have better optics.

#17 stevew

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Posted 02 October 2013 - 08:38 PM

If the Lunt 102ED is another re-branded version of this scope by Kumning United Optics then I think you can rest assured that it's well built, and a very good value.
I have the 110mm version labeled as an Orion ED, and the lens has a very good figure.
I believe Stellarvue also sold these scopes with their name on them.

Steve

#18 CollinofAlabama

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Posted 02 October 2013 - 10:39 PM

I have the Orion version, too -- the 102mm. Optically, I like it VERY much. Not a true APO, yes, but I believe Jon Isaacs said it had the same level of chromatic aberration that a 102mm crown and flint F/21 instrument would possess, so, not very much. I love its small size, sliding dewshield, and relatively light weight -- not that it's cheaply built. It is not, but a 714mm fl optic with a 2" focuser shouldn't be hard to maneuver, and this scope possesses maneuverability. Rides very well on my original Portamount I reinforced by filling the hollow aluminum legs with wooden dowels.

But mine has one really big minus. The dual speed Crayford isn't very nice. If I didn't already own the EXCELLENT dual speed AstroTech 80ED, I might not mind it. Sadly, I've tasted the fruit of the fantastic dual speed focuser, and my Kunming 102mm F/7 has this one unfortunate characteristic. Wish someone would recommend a replacement or explain how I might put my Orion single speed 100mm ED focuser on it. Thg Kunming and Synta focusers are WAY different, and this would clearly require an adapter, but I've not heard of one since I first posed this some months ago.

But this is my Orion 102mm F/7. Sounds like Lunt hasn't cheaped out on the focuser the way Orion did. But accessories aside, the Kunming F/7 ED scope performs optically about perfect for a visual application, which is what mine does. No AP for me.

#19 audioaficionado

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Posted 03 October 2013 - 10:25 PM

François,

What what type of mounting adapter did you end up getting?

Also where did you mount your RACI?

#20 stevew

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Posted 04 October 2013 - 01:26 AM

I believe Jon Isaacs said it had the same level of chromatic aberration that a 102mm crown and flint F/21 instrument would possess, I love its small size, sliding dewshield, and relatively light weight

I'd agree with this statement about the performance, as the scope certainly delivers sharp crisp images.
But the compact size and ease of use is also one of it's best features.

Steve

#21 stevew

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Posted 04 October 2013 - 01:27 AM

I believe Jon Isaacs said it had the same level of chromatic aberration that a 102mm crown and flint F/21 instrument would possess, I love its small size, sliding dewshield, and relatively light weight

I'd agree with this statement about the performance, as the scope certainly delivers sharp crisp images.
But the compact size and ease of use is also one of it's best features.

Steve

#22 coutleef

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Posted 04 October 2013 - 09:46 AM

François,

What what type of mounting adapter did you end up getting?

Also where did you mount your RACI?


i did not need any adapter since the rings come with a dovetail that fits in my twiligth mount

the raci was fixed on tthe focuser using wholes already present

#23 audioaficionado

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Posted 04 October 2013 - 10:41 AM

:thanx: for that info.

#24 Globetrotteur

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Posted 31 December 2013 - 03:54 PM

Salut Francois!

Do you know if this scope is builded with FPL-51 or FPL-53 glass? I'm interested by this scope but I can't find many details online.

Merci
Jerome

#25 coutleef

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Posted 31 December 2013 - 04:33 PM

Not sure but i think it is an equivalent to fpl51

Bonne annee






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