Author Topic: First Light with Zhumell Z10 10” DOB  (Read 145 times)

maogrinjorli

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First Light with Zhumell Z10 10” DOB
« on: December 28, 2017, 07:58:14 PM »
This is really a beginner’s post but it’s about a reflector, so if I’ve put this in the wrong place please let me know. I’m just excited that after 2 months of obsessively researching “best first telescope” and going back and forth over what kind to get, I finally nabbed one this weekend: a 10” Zhumell Z10.

I took a considered risk and bought it used off of Facebook Marketplace, which I’d been scouring along with craigslist for a potential deal. The price was right ($325) and from the images it looked like it was in good shape. When I went to pick it up I was shocked to find it in basically like-new condition. Apparently the gentleman purchased the scope on the recommendation of one of his clients, and he had never really learned how to use it. He didn’t know what the fan was for or what “the little batteries here do” (laser collimator), and it sounded like it’d been a frustrating purchase for him. I know the recommendation of many folks is for beginners to “get a Dob,” but he was excited to downsize to a pair of binoculars.

I am also very much a beginner, but fortunately, thanks to this forum, I knew to start with a pair of binoculars before getting a telescope, advice that has already proven very useful.

My first thought when I saw the Z10 was, “Thank goodness it is not as big as I thought!” It is impossible to tell how big a telescope is from pictures online. I was prepared to basically have to transport a water heater, but the Z10 is actually quite manageable in two pieces. (Forget about moving them together unless you’ve got a dolly.) Getting the OTA on/off the base is very simple, though, which was a pleasant surprise.

Don’t get me wrong, it’s a big freakin’ telescope… I don’t think I would own anything bigger unless I had an observatory in the backyard… but for the 30ft or so I have to move it to observe, it should hopefully see a lot of use. (I can already see myself wanting a 4” refractor or 6” SCT for camping, though).

I took it out last night for the first time under clear but light-polluted Class 6 suburban skies. I knew it was likely out of collimation and the finder scope wasn’t aligned, so I accepted that I was going to have some trouble from the get-go. And while I did have some challenges, it was a rewarding learning experience.

First impressions:
So apparently one of the screws locks the focuser! That was a good five minutes trying to figure out why the knobs weren’t moving it. A bit of trial and error got that sorted out, though, and I was off and running.
Wow, it is much, MUCH harder to figure out where I am in the sky with a 30mm 2” eyepiece than it is with my 8x56 binoculars. This was probably the biggest surprise to me. Familiar constellations like Cygnus and Cassiopeia became unnavigable seas of stars in a telescope. It was pretty disorienting. Things got a little better when I managed to use Altair to align the finder scope, but man… this is going to take some practice to find anything. I need to order a Telrad or Rigel (apparently the latter fits between the eyepiece and finder scope?)
It took a long time to get used to moving the telescope around with the image reversed. Binoculars you just, you know, point and see the way you normally see, only better. With this telescope, though, everything is upside down and sideways. I found myself constantly moving in the wrong direction and then having to try and find my way back. I did get better by the end of the night… I even managed to track an airliner that flew into my vision for a few seconds… but I can tell this is going to take a lot of practice.
I need to get an observing chair. I have a lot of trees around me, so most of my observing is around the zenith, and while I’m 35 and in good shape, I’m 6’2” – 10 minutes of hunching over the telescope had me reaching for the Advil. Speaking of pains, I need to learn how to adjust the telescope without accidentally grabbing the finder scope. I kept trying to move the telescope while looking through the eyepiece and invariably grabbed the finder scope by mistake. Augh.
The most frustrating part of the whole night came from the eyepieces and my eyeglasses. My vision is pretty good, but I have some astigmatism and from what I’ve read that really affects the view esp. on wide-angle lenses like the 30mm. True enough, taking my glasses off let me see the whole FOV in the eyepiece, but I couldn’t get the stars sharp. When I kept my glasses on, I could only see one part of the FOV at a time, which was very frustrating. I couldn’t seem to find a way to just relax and look because I felt like I was always fighting to see. The eye relief on the Zhumell 30mm is supposedly 18mm, which I thought would be enough, but maybe the 22mm eye relief on the ES 82º 30mm would help? Else-wise I guess I’ll just need to wear contacts for stargazing…
Challenges aside, I did manage on my very first night out to get a glimpse of the moon. I also got a lovely, FOV-filling look at M31. The moon is of course easy to find, but to see a distant galaxy through the eyepiece was stunning. I chose M31 because I’ve been out with my binoculars over the past two months learning my way around and it’s one of the few DSO’s that I can reliably find. The sky was also being very generous, because even though I spent most of the night lost I did manage to see two satellites whizzing by. Cool!

It’s supposed to be clear tonight again, and I’m excited to try for some star clusters. Thanks again for all of the helpful information you guys have collected in these forums. I feel like I got a head start thanks to all of the information gathered here.



isanruptysp

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Re: First Light with Zhumell Z10 10” DOB
« Reply #1 on: December 29, 2017, 01:05:55 AM »
Welcome and I must say a great first telescope for a great price. I have its big and little brothers,
a Z12 and a Z8. Yes, a Telrad makes locating your targets much easier. I use a 4" riser on mine
so I don't have to get on my knees and plant my face along the OTA. Put the Telrad as far up the
tube as possible, right to the end. Between the RACI finder and focuser is perfect.

The 30mm widefield eyepiece that comes with the scope is nice for a giveaway eyepiece but it has
a lot of astigmatism of its own. The astigmatism may be coming from the eyepiece, not your eyes.

An observing chair does help for comfort.

Practice is what you need more than anything. After you learn how to use your scope you can then
concentrate on finding targets to observe. If you can see the Milky Way, just point your scope in that
direction for an entire night of cool stuff.

Anything that you need more help with, just let us know.

Corey Gibson

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Re: First Light with Zhumell Z10 10” DOB
« Reply #2 on: December 30, 2017, 09:58:04 PM »
Congrat's on your new scope! You got a very good deal on that BTW. The Z10 is the one I typically recommend for a lifetime, do-all scope.

Regarding eyepieces and abberations:
You are seeing 2 major abberations that are affecting your views, which will be worse at lower powers.
1. The astigmatism in your eyes.
2. Coma from the telescope optics.

The best way to battle #1 is to use high-quality eyepieces with very long eye relief, combined with your glasses or a Dioptrx astigmatism corrector. I use Televue and Explore Scientific eyepieces with good results. One problem with ES is that you cannot trust their stated eye relief. The ES 30/82 does not have anywhere near 22 mm. While it is a fantastic eyepiece, there is no way to see the entire fov wearing glasses. My ES 34/68 has plenty of eye relief though for use with glasses, as does my Nagler 22T4 (highly recommended). I have a Dioptrx fitting to both the 22 and 34, and get excellent results at the eyepiece.

To tackle #2, you will need a coma corrector. I use the Televue Paracorr, whoch I purchased used for $215. It, combined with the eyepieces above, give me refractor-like views, except for the diffraction spikes.

Absolutely get yourself an observing chair. I would look at Starbound and Stardust chairs, which are both well received on these forums.

Charlie Carpenter

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Re: First Light with Zhumell Z10 10” DOB
« Reply #3 on: December 31, 2017, 05:16:09 AM »
To the OP:

Do you notice bad stars in the outer half of your finder scope? I just got a Z10 from facebook marketplace myself and have only had it out once. I was able to collimate it and look at a few objects and was pretty happy with the scope over all. My finder on the z10 is horrible compared to my Orion 9x50 RACI finder. Was trying to figure out if I got a bad finder, or if they are all like that with the z10.

Matt Haines

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Re: First Light with Zhumell Z10 10” DOB
« Reply #4 on: December 31, 2017, 07:37:29 AM »
Quote
snip...

First impressions:
So apparently one of the screws locks the focuser! That was a good five minutes trying to figure out why the knobs weren’t moving it. A bit of trial and error got that sorted out, though, and I was off and running.
Wow, it is much, MUCH harder to figure out where I am in the sky with a 30mm 2” eyepiece than it is with my 8x56 binoculars. This was probably the biggest surprise to me. Familiar constellations like Cygnus and Cassiopeia became unnavigable seas of stars in a telescope. It was pretty disorienting. Things got a little better when I managed to use Altair to align the finder scope, but man… this is going to take some practice to find anything. I need to order a Telrad or Rigel (apparently the latter fits between the eyepiece and finder scope?)
It took a long time to get used to moving the telescope around with the image reversed. Binoculars you just, you know, point and see the way you normally see, only better. With this telescope, though, everything is upside down and sideways. I found myself constantly moving in the wrong direction and then having to try and find my way back. I did get better by the end of the night… I even managed to track an airliner that flew into my vision for a few seconds… but I can tell this is going to take a lot of practice.
I need to get an observing chair. I have a lot of trees around me, so most of my observing is around the zenith, and while I’m 35 and in good shape, I’m 6’2” – 10 minutes of hunching over the telescope had me reaching for the Advil. Speaking of pains, I need to learn how to adjust the telescope without accidentally grabbing the finder scope. I kept trying to move the telescope while looking through the eyepiece and invariably grabbed the finder scope by mistake. Augh

snip
Congratulations on the new scope. That was an outstanding first light report.  Great Job!

I copied these because I followed the same path and had some of the same challenges?

Locked Focuser - I had the same issue.  Why won't the focuser work?  Hummm, wonder what this does. Oh, it is a lock!I started with 10X50 binoculars and often use binoculars to start and finish my telescope observing sessions. I still use them often, especially when I only have a few minutes or when it looks like clouds are going to roll in.

I find star hopping with 10X50 binoculars much easier than with my 9X50 finder scope. The binoculars seem to see more and things are brighter in the binoculars.  When I am star hopping I usually do the hop with the binoculars first, then go to the scope and the finder scope.

I added a red dot finder to my scope to help me with the initial pointing. I think a Telrad is a better choice. Just mount it on the tube with double sided tape. So easy.The reversed image didn't seem to bother me as much as I thought it would.  Not sure why.Observing Chair - I am also 6'2" - nuff said!  You need an observing chair.

Observation Chair- Denver Chair – Works Great!
I built this one . It took about 2 hours. Can be built from scrap but if you went all new, about $30.http://valleystargazers.com/Chair.pdfMy Dob lives on a cart in my garage. ( see photo below)  Open the door, roll it out, lift it off the cart. You can do the same thing with a hand truck. No temperature adjustments.  If you have a well ventilated, unheated garage, that is a great place to keep the scope as it will be temperature equalized as soon as you pull it out.Finding targets

Using an angle gauge to help find targetshttps://www.cloudyni...y/#entry8120838Create a list of targets sorted by constellation using Tonight's Sky -http://www.cloudynig...ights-sky-free/Star hopping 101 – Video play listhttps://www.youtube....6B0AD5D29A76981

Messier – Telrad Chartshttp://www.atmob.org...aps_jsmall.htmlAttached Thumbnails




Ethan Gechem

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Re: First Light with Zhumell Z10 10” DOB
« Reply #5 on: January 07, 2018, 10:30:02 PM »
Quote
First impressions:
So apparently one of the screws locks the focuser! That was a good five minutes trying to figure out why the knobs weren’t moving it. A bit of trial and error got that sorted out, though, and I was off and running.
Wow, it is much, MUCH harder to figure out where I am in the sky with a 30mm 2” eyepiece than it is with my 8x56 binoculars. This was probably the biggest surprise to me. Familiar constellations like Cygnus and Cassiopeia became unnavigable seas of stars in a telescope. It was pretty disorienting. Things got a little better when I managed to use Altair to align the finder scope, but man… this is going to take some practice to find anything. I need to order a Telrad or Rigel (apparently the latter fits between the eyepiece and finder scope?)
It took a long time to get used to moving the telescope around with the image reversed. Binoculars you just, you know, point and see the way you normally see, only better. With this telescope, though, everything is upside down and sideways. I found myself constantly moving in the wrong direction and then having to try and find my way back. I did get better by the end of the night… I even managed to track an airliner that flew into my vision for a few seconds… but I can tell this is going to take a lot of practice.
I need to get an observing chair. I have a lot of trees around me, so most of my observing is around the zenith, and while I’m 35 and in good shape, I’m 6’2” – 10 minutes of hunching over the telescope had me reaching for the Advil. Speaking of pains, I need to learn how to adjust the telescope without accidentally grabbing the finder scope. I kept trying to move the telescope while looking through the eyepiece and invariably grabbed the finder scope by mistake. Augh.
The most frustrating part of the whole night came from the eyepieces and my eyeglasses. My vision is pretty good, but I have some astigmatism and from what I’ve read that really affects the view esp. on wide-angle lenses like the 30mm. True enough, taking my glasses off let me see the whole FOV in the eyepiece, but I couldn’t get the stars sharp. When I kept my glasses on, I could only see one part of the FOV at a time, which was very frustrating. I couldn’t seem to find a way to just relax and look because I felt like I was always fighting to see. The eye relief on the Zhumell 30mm is supposedly 18mm, which I thought would be enough, but maybe the 22mm eye relief on the ES 82º 30mm would help? Else-wise I guess I’ll just need to wear contacts for stargazing…[snip]

Nice write up, Mithras. I think you're going to catch on quickly. A couple of suggestions on your first impressions....

"It took a long time to get used to moving the telescope around with the image reversed. Binoculars you just, you know, point and see the way you normally see, only better. With this telescope, though, everything is upside down and sideways. I found myself constantly moving in the wrong direction and then having to try and find my way back. I did get better by the end of the night…"

I trained myself to move the telescope by these phrases: Aiming the finder, move the telescope so that the cross-hair covers your target. Aiming the telescope, push on the telescope in the same direction that you want the target object to move. It's normal for the inverted image to slow one down at first. Remember, when looking through the eyepiece, push the telescope tube in the direction you want the object to move.

[snip] " ....True enough, taking my glasses off let me see the whole FOV in the eyepiece, but I couldn’t get the stars sharp. .."..[snip]

Regarding sharp stars...
On a large telescope like your Z10, heat retained in the mirror during storage roils the cool night air surrounding your primary mirror outside. It will always cause frizzy star images early in the session until the heat dissipates. Using your fan will shorten the length of the frizzy period. You can't really judge the telescope's image fidelity until it has cooled almost to ambient temperature.
On a large telescope like your Z10, scintillation of star images is more noticeable. That can contribute to those ugly star images. The term 'seeing' is given to the phenomenon. Scintillation is induced by the atmosphere itself. Some nights, scintillation (seeing) is bad; some nights it's almost undetectable (good seeing). Nights of good seeing are a joy to behold.
Do an optical telescope test of the telescope. Do it only after the telescope has cooled to ambient temp (like just before you are ready to put it away for the night).
Here is the test:
point the telescope to a bright star, Polaris for instance.
Center the star in your 9mm eyepiece.
Defocus Polaris until you see concentric rings form around the star. You want to be able to see only three or four of these rings.. More than that, you've defocused too much.
Look at the ring structure that has formed (remember to keep Polaris centered in the eyepiece the whole time). Do the rings form a complete circle around the central bright zone?
Look at the image both with your glasses on and off. Do the rings appear round? Oval? Triangular? Is there a difference with your glasses on?
Sometimes the telescopes ship from the factory with the mirror clips too tight and the pressure from the clips will affect the shape of the rings. If that's noticeable in your test, it is something that you can fix yourself.
----------
C

Randy Wiggins

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Re: First Light with Zhumell Z10 10” DOB
« Reply #6 on: January 08, 2018, 03:23:42 AM »
Things you might consider for future purchases

I think this is the eyepiece that came with your scope:
http://agenaastro.co...w-eyepiece.html

Gives you 41X and 1.65 degrees FOV. Not bad!

For my Orion XT8i I have a 38 mm 70 degree Agena Astron SWA
http://agenaastro.co...a-eyepiece.html

In your scope it would yield 32.9X and and 2.13 degree FOV.  I use this a lot as my next step up from the finder scope when I need more mag and more light gathering to see the guide stars.   Also gives you more of M31 and the Pleiades and other large clusters.And then I am a zoom eyepiece fiend.  I love my zoom eyepieces. They are my primary eyepieces.  Something to consider.

agtofonist

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Re: First Light with Zhumell Z10 10” DOB
« Reply #7 on: January 08, 2018, 06:18:50 AM »
Quote
Things you might consider for future purchases

I think this is the eyepiece that came with your scope:
http://agenaastro.co...w-eyepiece.html

Gives you 41X and 1.65 degrees FOV. Not bad!

For my Orion XT8i I have a 38 mm 70 degree Agena Astron SWA
http://agenaastro.co...a-eyepiece.html

In your scope it would yield 32.9X and and 2.13 degree FOV.  I use this a lot as my next step up from the finder scope when I need more mag and more light gathering to see the guide stars.   Also gives you more of M31 and the Pleiades and other large clusters.And then I am a zoom eyepiece fiend.  I love my zoom eyepieces. They are my primary eyepieces.  Something to consider.

I like my Televue zoom (basically the Vixen LV zoom rebranded). I would put it on par with my former set of Atrotech Paradigm eyepieces (with a slightly narrower FOV). Of course, once I start wanting higher power ultra wide field for DSO hunting, that will be a different matter. But for the targets I use it for, the zoom is awesome.

asagnata

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Re: First Light with Zhumell Z10 10” DOB
« Reply #8 on: January 12, 2018, 01:29:15 AM »
I like my Celestron 8-24 Zoom.

But I LOVE the Baader Hyperion 8-24 Zoom.  A low power wide view eyepiece, the BHZ and a barlow is often all I use all night. I have 20 other eyepieces but mostly I don't use them anymore.

bumabbefat

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Re: First Light with Zhumell Z10 10” DOB
« Reply #9 on: January 13, 2018, 01:17:18 AM »
Quote
To the OP:

Do you notice bad stars in the outer half of your finder scope? I just got a Z10 from facebook marketplace myself and have only had it out once. I was able to collimate it and look at a few objects and was pretty happy with the scope over all. My finder on the z10 is horrible compared to my Orion 9x50 RACI finder. Was trying to figure out if I got a bad finder, or if they are all like that with the z10.

I have a feeling your finder scope is out of focus. To focus your scope first turn the locking ring behind the finder main
objective. Turn it several times to give it a lot of play. Then turn the main objective one way, then the other,
while looking through the eyepiece to see if you are going in the right direction. When you achieve best focus
then turn the locking ring back to clamp it down. The finder isn't a super high quality but it does work quite well
and is better than many if not most dob finders.

Matt Gibbs

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Re: First Light with Zhumell Z10 10” DOB
« Reply #10 on: January 13, 2018, 03:09:10 PM »
Quote
Quote

To the OP:

Do you notice bad stars in the outer half of your finder scope? I just got a Z10 from facebook marketplace myself and have only had it out once. I was able to collimate it and look at a few objects and was pretty happy with the scope over all. My finder on the z10 is horrible compared to my Orion 9x50 RACI finder. Was trying to figure out if I got a bad finder, or if they are all like that with the z10.

I have a feeling your finder scope is out of focus. To focus your scope first turn the locking ring behind the finder main
objective. Turn it several times to give it a lot of play. Then turn the main objective one way, then the other,
while looking through the eyepiece to see if you are going in the right direction. When you achieve best focus
then turn the locking ring back to clamp it down. The finder isn't a super high quality but it does work quite well
and is better than many if not most dob finders.
It's in the best focus I could get it. The center stars are nice and tight, but I start to notice aberrations about 1/3 of the way out, and in the outer third the stars look like the edge of a super wide angle eyepiece in a fast newt with a with no coma corrector. Turning the objective either way just defocuses the good stars in the middle.

Owen Richter

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Re: First Light with Zhumell Z10 10” DOB
« Reply #11 on: January 13, 2018, 08:57:30 PM »
MithrasTheArcher:

Great write up.. And congratulations on your new scope..

My 10 inch F/5 Dob is a 15 year old version of the same scope. It's been a good scope.. A few thoughts and experiences:

- Chair: An adjustable chair is very nice but a simple folding chair works quite well. Saves a lot of bending.

- Astigmatism and sharp stars: There's a lot to think about here, your eyes, the telescope, the eyepiece.

Before discussing this, the important question is this:. Without your glasses, were you able to achieve relatively sharp focus on stars in the very center of the field? if so, that means your eyes are not the problem. Here's how it works:

The astigmatism in your eyes affects the entire field of view, the center out to the edge. If you are seeing sharp stars in the center, that means your eyes are not the problem.

Your 30 mm 2 inch eyepiece is a nice finder eyepiece and an entry level 2 inch wide field. It's reasonably sharp in the center of the field but away from the center of the field it shows more and more off-axis astigmatism. This is typical in an F/5 scope. In an F/10 scope the outer field would be relatively clean but at F/5, it suffers.

Wide field eyepieces that are relatively free of off-axis astigmatism at F/5 are expensive. Prior to TeleVue and the first Naglers, such eyepieces did not exist. TeleVue eyepieces are still the best in this regard but there are others that are quite good that are more affordable but don't expect a $100 2 inch wide field to be much better than what you have.

I think the best attitude is just accept the view for what it is, sharp in the center, not so sharp away from the center and just enjoy the view.

An F/5 Newtonian also has a noticeable amount of coma, tiny comet like tails on stars towards the edge of the field. Compared to the eyepiece's off-axis astigmatism, the coma is relatively minor.

- Finders:. The 50 mm RACI finder is nice because it agrees with a chart but it's difficult to line up on that first star, to get into the right area. I find a Telrad to be ideal for this and under darker skies whether there's plenty of stars visible naked eye, often the object can be placed in the field of view the main eyepiece without using the magnifying finder.

- Tracking: Soon enough it will be second nature and you will move the scope the right way without thinking about it. Your Dob is a left handed Dob, you track with your left hand..

Bottom line, you got yourself a winner, enjoy it, there's a lot to learn.. at lot to see.. a lot of fun ahead..

Jon

chirafepes

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Re: First Light with Zhumell Z10 10” DOB
« Reply #12 on: January 14, 2018, 01:51:54 AM »
Quote
Quote

Quote

To the OP:

Do you notice bad stars in the outer half of your finder scope? I just got a Z10 from facebook marketplace myself and have only had it out once. I was able to collimate it and look at a few objects and was pretty happy with the scope over all. My finder on the z10 is horrible compared to my Orion 9x50 RACI finder. Was trying to figure out if I got a bad finder, or if they are all like that with the z10.

I have a feeling your finder scope is out of focus. To focus your scope first turn the locking ring behind the finder main
objective. Turn it several times to give it a lot of play. Then turn the main objective one way, then the other,
while looking through the eyepiece to see if you are going in the right direction. When you achieve best focus
then turn the locking ring back to clamp it down. The finder isn't a super high quality but it does work quite well
and is better than many if not most dob finders.
It's in the best focus I could get it. The center stars are nice and tight, but I start to notice aberrations about 1/3 of the way out, and in the outer third the stars look like the edge of a super wide angle eyepiece in a fast newt with a with no coma corrector. Turning the objective either way just defocuses the good stars in the middle.
Well, sounds like you are correct that your finder isn't up to speed. Can you switch the Orion finder for it?
There are some nice, after market finders that provide an upgrade but that's money you probably didn't
want to spend. Sorry, can't think of another solution.

foarehortalp

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Re: First Light with Zhumell Z10 10” DOB
« Reply #13 on: January 21, 2018, 12:57:11 AM »
Wow, pretty nice scope for your first one, congrats!

Lot's to see and get acustomed too. You have come to the right place, lot's of good friendly advise to help you out. I have that scope and bought a Starbound chair to go along with. For viewing up at the Zemith overhead, I'm just about sitting on the ground with it. After the full moon is over, take the 30mm and point the scope up to the Cygnus area of the sky....you will be overwhelmed with stars!

You need some better eypieces, that 9mm that came with it is very limited and hard for me to see in it. Look into something in the 20mm range and something in the 11-13mm range. Also the EP should have at least a 60* FOV and 68 and 82 are real nice in that scope.

Download the free program, Stellarium to your computer. It will show you what your sky will look like on any night. It shows all the deep sky objects and how big and bright they are.

Astronomy magazine has a great observing issue called the Atlas of the Stars. I use it all the time and it's not that expensive and is filled with lot's of great star maps and pretty pictures!

Good luck with the scope.....BTW, where are you located?

Waka Belcher

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Re: First Light with Zhumell Z10 10” DOB
« Reply #14 on: January 21, 2018, 07:15:31 AM »
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Many thanks for the helpful and welcoming responses thus far! I've really enjoyed reading your thoughts and suggestions. I've taken some of them to heart – well, to wallet – already and ordered a Starbound observing chair and Telrad finder with a 4" riser. I'm looking forward to adding those pieces to my stargazing kit, with hopefully some eyepiece purchases to come once I do a little more homework.

I can't shake the feeling that I am about to spend a ton of money on this hobby. 

Actually, tamping down my excitement and holding off on spending money has been a theme from the get-go. After getting "starstruck" back in August, it was very hard to not rush out and buy a telescope right away. With all of the options available and competing philosophies on how best to start, it was actually pretty overwhelming. I'm glad I took my time and waited, as it sounds like I really did get a good deal on this Z10 and it is a scope I can grow into.

I spent some time yesterday afternoon on YouTube learning how to collimate. This process loomed large in my mind and sounded like a real chore – a "reflector tax" – but in practice it was actually kind of fun to try and get the red dots to line up. I know that the really serious folks here collimate their collimators, but for my first time I just decided to let the factory-default laser do the work. Whoever had done this process before me really tightened the screws on the secondary mirror. I was afraid I was going to twist it right off - eep! - but they eventually came loose enough to adjust. Tweaking the primary took some fiddling, but I think I did it correctly. The stars looked a bit sharper to me, though I corrected the secondary first and the primary second and I've read in the interim that you're supposed to collimate Primary > Secondary > Primary. I'll try again ahead of my next observation.

With young children and a full-time job, I've got limited time/energy for setting up equipment, which is why I'm trying to make this scope as grab-n-go as possible. I'm keeping the scope covered in a shed in the backyard (including a shower cap around the bottom of the OTA to keep out spiders because ew). I do worry a bit about rust and dust, but the shed is about 15ft from the best observing spot in the yard and the scope is protected from the elements but not climate controlled. I think for right now this is the best solution to eliminating cool down time, reducing the distance I have to carry the scope, and also keeping it where my kids can't turn the steel OTA into a steel drum and spin it around on its base as fast as they can (see also: why I'm collimating it again ).

Question: Do eyepieces need cool down time too, or just the telescope mirrors? I've been keeping the eyepieces in a case in the house.

Regarding the finder scope, I took the telescope out last night and specifically looked for reduced quality in the outer half of the FOV. To my eyes, the stars on the outer half of the finder scope are less clear than the ones in the center. I did fuss with the focus of it and got things usably sharp in the center, but my general experience with the finder has been pretty frustrating overall. I'm eager for the Telrad to arrive.

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I trained myself to move the telescope by these phrases: Aiming the finder, move the telescope so that the cross-hair covers your target. Aiming the telescope, push on the telescope in the same direction that you want the target object to move. It's normal for the inverted image to slow one down at first. Remember, when looking through the eyepiece, push the telescope tube in the direction you want the object to move.

[snip] " ....True enough, taking my glasses off let me see the whole FOV in the eyepiece, but I couldn’t get the stars sharp. .."..[snip]

Regarding sharp stars...
<ul class="bbc">On a large telescope like your Z10, heat retained in the mirror during storage roils the cool night air surrounding your primary mirror outside. It will always cause frizzy star images early in the session until the heat dissipates. Using your fan will shorten the length of the frizzy period. You can't really judge the telescope's image fidelity until it has cooled almost to ambient temperature.
On a large telescope like your Z10, scintillation of star images is more noticeable. That can contribute to those ugly star images. The term 'seeing' is given to the phenomenon. Scintillation is induced by the atmosphere itself. Some nights, scintillation (seeing) is bad; some nights it's almost undetectable (good seeing). Nights of good seeing are a joy to behold.
Do an optical telescope test of the telescope. Do it only after the telescope has cooled to ambient temp (like just before you are ready to put it away for the night).

Here is the test:
<ul class="bbc bbcol decimal">point the telescope to a bright star, Polaris for instance.
Center the star in your 9mm eyepiece.
Defocus Polaris until you see concentric rings form around the star. You want to be able to see only three or four of these rings.. More than that, you've defocused too much.
Look at the ring structure that has formed (remember to keep Polaris centered in the eyepiece the whole time). Do the rings form a complete circle around the central bright zone?
Look at the image both with your glasses on and off. Do the rings appear round? Oval? Triangular? Is there a difference with your glasses on?

Sometimes the telescopes ship from the factory with the mirror clips too tight and the pressure from the clips will affect the shape of the rings. If that's noticeable in your test, it is something that you can fix yourself.
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C

All of these posts have been helpful, and I found this one to be especially so. "Push the telescope in the direction you want the object to move" was a GAME-CHANGER last night. Thank you! It was much easier to move around in the sky with this advice in mind. I even had another airliner fly into my FOV and tracked it for 15 seconds before it passed the zenith.

I did attempt to perform this star test as described. I centered Algol in the eyepiece and defocused it. Instead of seeing concentric rings, however, I saw what can only be described as a psychedelic display of pulsing colors and swirling currents. Is this the "scintillation" you're referring to? The defocused image was large and round, with four little indents on each of the poles of the star. It was, frankly, beautiful. I could have watched it for an hour. I'm not sure what it says about the optics, as this sounds like it has more to do with seeing conditions. I'll try it again on a star a bit higher in the sky next time.

<p class="citation">Jon Isaacs, on 03 Oct 2017 - 11:03 AM, said:<a href="https://www.cloudynights.com/index.php?app=forums&amp;module=forums&amp;section=findpost&amp;pid=8136685" rel="citation">[/url]<blockquote class="ipsBlockquote built" data-author="Jon Isaacs" data-cid="8136685" data-time="1507021433">
MithrasTheArcher:

Great write up.. And congratulations on your new scope..

My 10 inch F/5 Dob is a 15 year old version of the same scope. It's been a good scope.. A few thoughts and experiences:

- Chair: An adjustable chair is very nice but a simple folding chair works quite well. Saves a lot of bending.

- Astigmatism and sharp stars: There's a lot to think about here, your eyes, the telescope, the eyepiece.

Before discussing this, the important question is this:. Without your glasses, were you able to achieve relatively sharp focus on stars in the very center of the field? if so, that means your eyes are not the problem. Here's how it works:

The astigmatism in your eyes affects the entire field of view, the center out to the edge. If you are seeing sharp stars in the center, that means your eyes are not the problem.

Your 30 mm 2 inch eyepiece is a nice finder eyepiece and an entry level 2 inch wide field. It's reasonably sharp in the center of the field but away from the center of the field it shows more and more off-axis astigmatism. This is typical in an F/5 scope. In an F/10 scope the outer field would be relatively clean but at F/5, it suffers.

Wide field eyepieces that are relatively free of off-axis astigmatism at F/5 are expensive. Prior to TeleVue and the first Naglers, such eyepieces did not exist. TeleVue eyepieces are still the best in this regard but there are others that are quite good that are more affordable but don't expect a $100 2 inch wide field to be much better than what you have.

I think the best attitude is just accept the view for what it is, sharp in the center, not so sharp away from the center and just enjoy the view.

An F/5 Newtonian also has a noticeable amount of coma, tiny comet like tails on stars towards the edge of the field. Compared to the eyepiece's off-axis astigmatism, the coma is relatively minor.

- Finders:. The 50 mm RACI finder is nice because it agrees with a chart but it's difficult to line up on that first star, to get into the right area. I find a Telrad to be ideal for this and under darker skies whether there's plenty of stars visible naked eye, often the object can be placed in the field of view the main eyepiece without using the magnifying finder.

- Tracking: Soon enough it will be second nature and you will move the scope the right way without thinking about it. Your Dob is a left handed Dob, you track with your left hand..

Bottom line, you got yourself a winner, enjoy it, there's a lot to learn.. at lot to see.. a lot of fun ahead..

Jon
I tried observing last night with glasses on and off to get some more data points on what is actually happening with the glasses/eyepieces. I learned that without my glasses on, I'm unable to get the stars sharp in the center of the 30mm eyepiece. (The view is slightly better with my right eye than with my left, though.) With my glasses on, I can get some of the image sharp, but as you all noted the stars in the outer 1/3rd of the eyepiece all have little comet trails no matter what I do. I don't entirely understand the reason my scope has such a fast focal ratio, but I do understand from this thread that it will take some premium components – coma corrector, really good eyepieces – to maximize the quality of the view.

Happily, the 9mm is much sharper, even with my glasses off. The recommended Baader or Televue 1.25" zoom eyepiece with a Dioptrx sounds like it might be a great place to start.

One thing I am wondering: In the 30mm, depending on the angle I'm looking into the eyepiece, some of the brighter stars in the center have a little comet trail that appears either on the right or left side of the star depending on how I move my head. Is this an indication that the collimation is out? I know the importance of collimation from reading, but I don't actually know what a poorly collimated scope looks like through the eyepiece.

All that said, I did manage to take in some wonderful views despite a blindingly bright Moon in the sky last night.

First, I looked at the Moon because, well, it was omnipresent. I made the mistake of training on it with the 30mm eyepiece and no moon filter. Holy Blinding Light, Batman, that thing is LIT UP. A few seconds of that and it occurred to me I might actually be damaging my retina. 10" of light gathering on an object illuminated by the sun is WAY too much. Oof. For the next 10 minutes one of my eyes was night-corrected and the other was ready to stand on the beach in Miami. I switched out for the 9mm with the included moon filter, which was much more pleasant, although I couldn't get over how fast the Moon fled the FOV. It just moves shockingly fast. I couldn't get over it. That thing really books it across the sky in a way that is totally unnoticed in regular life.

The rest of the night was spent hunting down the Hyades and Pleiades, both of which offered sparkling (albeit not very sharp) views in the 30mm. I even managed to stumble on the Double Cluster in Perseus, which was thrilling. So many stars! The telescope resolved a lot of individual ones, which was lovely. I was a little disappointed by how light the background was, but I think that was the Moon's doing.

All in all, it was a very satisfying second night out. Still lots to learn. I spent a ton of time fighting with the finder and just pushing the telescope around trying to find things, but once I relaxed and tried to enjoy the wandering, I had a great time.