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New Moon Telescopes 20”F/3.3 Review


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New Moon Telescopes 20”F/3.3 Review

 

It's been just over six months of usage of the NMT 20"F/3.3 telescope and I feel it’s about time I share my experience with it.

 

The scope and a NMT observation chair are waiting for dark skies in the Israeli desert

 

I have been hooked on astronomy ever since childhood, but life always pulled me in different directions, until two years ago. At that time I got an achromatic refractor and from there the sky stopped being the limit. After that I moved to a Sky Watcher 12" Dob and quickly understood that I loved dobs, and wanted a bigger one.

 

How big? As big as I can handle.

 

Currently owned scopes:

NMT 20"F/3.3

Celestron 8" Evolution

 

 

On my future list:

A sun scope for visual use

An Apo refractor for wide field views

 

I have set the following requirements for a big dob:

- No need for a stool/ladder

- Fits in my car

- Secure during drive

- Secure in the field

- Easy to assemble/disassemble

- Good optics

- Collimation hold

- Last but not least - Mechanics

 

The option of a 20" was not on the table - I didn't know that such big and fast scopes are available to amateurs and once I did, the price was a bit of a blocker. However, doing some math (more with my heart than with my head) made me realize that compromising on an expensive instrument will only cause me regrets and eventually, I decided to buy the one I really want.

 

After some research and discussions with a few vendors and Ryan from NMT, I realized that this is the instrument that answers my needs.

 

I ordered the 20"F/3.3 with Fullum Optics Mirror, Feathertouch ultralight focuser, Secondary dew heater, Thousand oak dew controller, Telrad, mount for optical finder, wheelbarrow handles and a custom Tablet & 2” eye pieces stalk and with the selected type of woods - you get to choose which type each part is made - full customization.

 

Build process images were shared constantly.

 

The scope arrived on time.

 

After six months of usage I am ready to share my experience and double check how the scope answered my requirements:

 

No need for a stool/ladder:

The focuser in zenith is at the correct position - flat feet and no stretching the neck is required

 

Fits into my car:

Fits. This was known of course, but the first time I loaded it was a bit scary. The scope is not light weighted - its mirror box (with mirror included) is 61 pounds. I managed to lift it alone on a few occasions, But I prefer a pair of aluminum ramps for loading. The wheelbarrow comes with big wheels, making the process of loading easy.

 

Folding Loading Ramps

 

Secure during drive:

The mirror box is solid and there is a wooden cover to protect it, no flexible plastic covers here. Very secure

 

Secure in the field:

Again, the mirror is within a solid box and is well protected. There is a very small opening in the back,  but it exposes the bottom of the mirror, not its surface.

 

Easy to assemble/disassemble:

Assembly is a breeze. I remember attending an outreach in which a specific 18" truss scope was assembled - by 4 people. Out of the box, Assembling the NMT was easy - and it was the first time I assembled a Truss scope myself. disassembling is easy as well. The only thing that might be considered hard is loading/offloading from the car. Again, with the ramps, I can do it alone.

 

Collimation hold:

I did not notice a worsening in views during a full night. I tested it at the end of the night once as using a cheshire requires light. It was still collimated. Many warned that a scope that fast requires extra precise collimation. So it's a laser for rough collimation and a cheshire for the final tuning. Works like a charm.

 

Mechanics:

I can't stress enough how important the mechanics are in a scope. My 12" had a slight backlash when moving, the movement was not very smooth, it had freedom that could suffer from wind (actually moved) and its balance was terrible - using ES 24mm/82 eyepiece caused it to sag when pointing below 30 degrees.

 

The NMT does all of this differently. First of all, although there is the option to mount counterweights, there is no need. The altitude bearings are big and provide extraordinary balance. The scope stays balanced with a Nagler 31mm + Paracorr type 2 + optical finder or without any accessory!

 

Horizontal movement is also smooth but with a bit firmness, preventing the scope from moving from stray wind gusts.

 

Replacing eyepieces leaves the scope right on target.

 

The combination of smoothness, firmness and no need for counterweights makes this instrument mechanically perfect.

 

(balanced perfectly with everything mounted on top)

 

Optics and View:

I am no expert in this area and my eyes are not perfect, I will share my experience with it and stuff that friends noted.

 

- Nebulae - The views are amazing and exceeding anything I expected. Lots and lots of details. From Orion to California, to Veil to the summer Nebulae all look fantastic. It was the first time I saw the Horse head. no need for averted imagination.

 

- Globular clusters - spectacular, stars can be seen very deep within them

 

- Open clusters - with this scope, open clusters jumped in priority for me as they are visible in their full glory. The double cluster, fitting in the field of view is just wonderful

 

-  Galaxies - Here comes the true power of the 20". More details than expected in the smaller galaxies, galaxies that were not there before suddenly pops out and the big ones - M51 for example - are full of details. Arms are distinguishable, details between them are clearly visible, swirls of dust and the arm that slaps NGC 5194. Viewed it with the 3-6 Nagler zoom and could discern so many details.

 

- Double stars - There are better scopes for splitting multiple stars. While stars are as pinpoint as possible in a F/3.3, it requires the best of conditions to view the bright ones in high magnification.

 

- Planets - I have mixed feelings about observing planets with this scope. The secondary mirror is huge and as such, the contrast suffers. In addition, such bright objects suffer greatly from bad atmospheric conditions. If it shakes, the image shakes. I did however manage to have one exceptionally good and stable night where the planets shone (shone and harmed my night vision) with many details visible such as Encke Gap on Saturn and On Jupiter, swirling clouds could be visible.

 

- Moon - Here, even with the huge central obstruction, the moon, even going to the limit of my manual tracking and atmospheric disruptions is very vivid and full of details. One can lose himself in lunar views.

 

Comments from friends and colleagues:

One friend indicated an astigmatism that is noticeable in high magnifications, others, not less experienced than him, viewed in x450 & x600 and did not notice any issue.

 

A friend with an 18" noted that he could see more details in M51, and others with many years of observation experience indicated that they had the best views using this scope.

 

Our astronomy club elder noted the excellent quality of the mirror, He was amazed that an F/3.3 could provide such performance.

 

Any one that observed through the scope noted the superb mechanics and fun of handling it.

 

Improvements?

Maybe getting the scope with a full UTA could have been better - secondary mirror more protected during drive and without a special case I ordered for it, could even take less space in the car. In addition, the Focuser position could have been placed a bit higher and not leveled with the ground which could have made viewing very low objects a bit easier (usually I don’t go that low).

 

- Full UTA might handle dew better?

 

- Removable altitude bearings can dramatically reduce the scopes footprint inside the car and is well to be considered (it would however complicate assembly/disassembly).

 

These issues have zero effect on my experience with the scope.

 

To sum things up

This instrument answers to all my requirements from a big dob and is mostly used during my dark site trips.

 

While double stars and planets are not the specialty of this scope, it handles them fairly well, but requires extra good conditions - backyard usage is not optimal as atmospheric disturbances dramatically affect the views.

DSOs is where this instrument excels and provides the best performance under dark skies, especially with faint galaxies.

 

During my last dark site session, after the COVID-19 restrictions lifted, I had barely time to observe myself as others lined up to view instead.

 

Bottom line:

For usage under dark skies, this is the best instrument I could get for myself. You buy such a scope once and you get a device for a lifetime!


  • Mark Strollo, George N, Neptune and 16 others like this


31 Comments

Mirror Box w/top ring mounted on brackets for travel.
 
Mirror Box w/top ring mounting brackets for travel.

 

Ilan asks:  The mounting brackets sounds like a good idea, care to share an image?

 

*** Your bucket idea is probably just as good, if not better. ***

 

I tried to attach some pictures... I had to load them into my albums first.  Top picture shows ring mounted above mirror box for travel; lower image shows the brackets themselves next to the scope.

Photo
ilan_shapira
Oct 31 2020 12:41 AM


 

 
 
 

 

Ilan asks:  The mounting brackets sounds like a good idea, care to share an image?

 

*** Your bucket idea is probably just as good, if not better. ***

 

I tried to attach some pictures... I had to load them into my albums first.  Top picture shows ring mounted above mirror box for travel; lower image shows the brackets themselves next to the scope.

 

The brackets is a nice idea Keeps the entire UTA stable.

Here is an image of my bucket:

gallery_299831_14856_600120.jpg

 

 

While it keeps the secondary protected, I do have to tie it to the mirror box and put something soft between them to prevent noises and slippage during drive.

 

Thanks for sharing

    • George N likes this

Hmmm... I can see better what you were getting at with the "bucket"; I wasn't scaling up the image of my little scope - I envisioned your entire ring wedged inside the bucket!  But you would probably need the sawed-off bottom of a plastic garbage can to fit your ring in.

 

But a problem with the brackets - and indeed, with all scopes that users dismantle at the end of a long night's observing session - is developing good *technique* by which the scope is transitioned to its travel configuration w/o damage.  While the ring is well supported by the brackets once you get it mounted, doing so while you are sleepy, cold, and in the dark can be problematic (as I have noticed).  And a ring as large as yours might be difficult to mount single-handed.

 

It has since occurred to me that a traditional dob scope top could be built - to a much cheaper standard, of course - for the sole purpose of suspending the ring in transit over the mirror box.  The down-side of this approach would be that you'd have this large cylinder to store in the vehicle while the scope is in use, vice a handful of brackets that can be stashed out of the way.  Anyhow, just some thoughts!

    • ilan_shapira likes this
Photo
ilan_shapira
Nov 01 2020 01:24 PM

Hmmm... I can see better what you were getting at with the "bucket"; I wasn't scaling up the image of my little scope - I envisioned your entire ring wedged inside the bucket!  But you would probably need the sawed-off bottom of a plastic garbage can to fit your ring in.

 

But a problem with the brackets - and indeed, with all scopes that users dismantle at the end of a long night's observing session - is developing good *technique* by which the scope is transitioned to its travel configuration w/o damage.  While the ring is well supported by the brackets once you get it mounted, doing so while you are sleepy, cold, and in the dark can be problematic (as I have noticed).  And a ring as large as yours might be difficult to mount single-handed.

 

It has since occurred to me that a traditional dob scope top could be built - to a much cheaper standard, of course - for the sole purpose of suspending the ring in transit over the mirror box.  The down-side of this approach would be that you'd have this large cylinder to store in the vehicle while the scope is in use, vice a handful of brackets that can be stashed out of the way.  Anyhow, just some thoughts!

At some point I ordered a huge padded box, 24" X 24" (cant remember the height) that keeps the mirror floating and keeps the entire ring stable - it would be the only thing to survive a car crash.

While not heavy it is big and bulky and takes hell lot of space in the car.

 

I usually load the rocker + mirror boxes using a ramp, place one of the mats I carry to the field. On top of it I place the bucketed ring and secure it.

On the field, fellow observers help to load/unload.

I do mount the ring single-handedly, its not difficult - this is one of the things I love about this scope.

However, If I am left the last one standing, I will cover the scope and load it in the morning.

 

I think that the bucket approach is the simplest and easiest to use, but the brackets are excellent for securing the thing in place.

Photo
SkywatcherBob
Dec 01 2020 01:05 AM

Ilan, Great review and comments.  I just picked up my 22" from Ryan a few weeks ago and still on learning curve.  Previous was 30+ year old C8 and didn't know collimation from column making.  After 1 night in backyard with first quarter moon (fantastic !) went to dark sky, but Full Moon meant not dark and also found planets too bright and Mars with 9mm and Paracoor still just too bright.  Like to know more about masks. What eyepieces are you finding best for galaxies?  Using the 3-6 Nagler 1.25" zoom? Still experimenting and waiting for Moon and clouds to leave.  Thanks for feedback and help.

Ryan 22%22 Dob
    • George N and ilan_shapira like this
Photo
ilan_shapira
Dec 01 2020 08:20 AM

Ilan, Great review and comments.  I just picked up my 22" from Ryan a few weeks ago and still on learning curve.  Previous was 30+ year old C8 and didn't know collimation from column making.  After 1 night in backyard with first quarter moon (fantastic !) went to dark sky, but Full Moon meant not dark and also found planets too bright and Mars with 9mm and Paracoor still just too bright.  Like to know more about masks. What eyepieces are you finding best for galaxies?  Using the 3-6 Nagler 1.25" zoom? Still experimenting and waiting for Moon and clouds to leave.  Thanks for feedback and help.

Congrats! that's an amazing scope and a huge jump from C8! 

 

Planets are tough - as I found as well. I did not try masks, but used a neutral density filter to observe Mars and a #80A blue filter for Jupiter. Saturn was fine without a filter but required a perfect conditions - very stable and clear air (got one or two of those per year).

 

What collimation tools do you have? collimation should be accurate as you can with these sizes and focal rations.

 

As for eyepieces, I like the Ethos 8mm for galaxies. It provides good magnification with a wide enough field for navigating galaxy clusters.

 

I once used the Nagler zoom 3-6 a friend brought to a session, used it on M51 & Ring nebula and the views was just amazing. I do plan to get me one of these.

 

My most used eyepiece is the Ethos 21mm. a wonderful all around, wide field. I usually switch between 21 and the 8. For bigger targets - Nagler 31mm is my preferred eyepiece.

 

Once you get a clear and dark skies, you are in for a treat, even more as you have tracking :)

 

I have a new FB group for NMT owners, very few of us so far as its not a common scope, you are more than welcome to it - https://www.facebook...055422524562329

    • The Ardent and SkywatcherBob like this


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