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asaint
Carpal Tunnel
Reged: 04/25/03
Posts: 2072
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Celestron NexStar 8i SE
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ForgottenMObject
Post Laureate
Reged: 09/11/04
Posts: 3589
Loc: Maryland, US
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Great report!
I've always had a thing for those "one-arm starships", though I've never owned one myself (I did have a Classic 8 for years, though), since they are by far the most portable of all the SCT designs. They don't have all the extra parts and counterweights of a GEM-mounted scopes, nor do the have the "lead fork-mount" of the standard 2-armed modern fork-mountes scopes, where an 8" SCT can weigh over 40-pounds in the fork and OTA assembly.
Glad to hear that the Sky Align feature works as advertised - that is really neat! Just point it at much of anything, and it works. Great stuff, and better than hunting down Rasalathingus or some other obscure alignment star.
I like the accessories, namely the right-angle mount for the hand controller, and glad that the Televue eyepieces did what they normally do, which is give astounding views.
One question: can the "one armed starships" be moved manually if the power is off? I forget if they have clutches for that or not.
--------------------
Matthew
IDA member
XT8i, 10x50 binoculars, lots of eyepieces
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 11748
Loc: Los Angeles
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Interesting perspective. Certainly, the 8i is a lot of scope for the price. And is the most portable 8" SCT made.
It will be a fun first scope to own. And the owner will learn a lot about the sky from using it.
From the perspective of a seller of a lot of different scopes, however, there are some major flaws in the 8i that are not present in the next Celestron model upm the C8-SGT, which is only about $115 more.
The 8i's flaws, as I see it:
1. The altitude clutch doesn't lock. Heavy accessories can cause the altitude to "creep".
2. The azimuth is not movable without power. You cannot loosen a screw and turn it manually. This is a minor flaw, as I think anyone in the field should have a charged battery to use. The internal batteries don't last long.
3. The scope is not usable with a 2" visual back. On a 6" or smaller scope, this is not a problem. But the 8" SCT's maximum field of view is ONLY achievable with a 2" diagonal and 2" eyepiece. So the FOV is restricted to .8 degrees or less. There isn't even room for a focal reducer between the scope and base.
4. The shimmy is too present. If you add a dewshield, essential on any SCT, and there is the slightest breeze, the shimmy never stops. The shimmy makes focusing at high power nearly impossible because the beating of your heart causes the scope to bounce when your hand is on the focus knob. You have to focus, take your hand away, refocus, etc. to find the correct focus.
5. All the 8i's I've seen have play in the altitude axis. You can grab the tube and move it up and down slightly before the gears hit. It might be as simple as adjusting the gears to mesh a little more tightly, but this is not user serviceable.
6. The plastic plate the hand controller hooks on to keep it in the arm is very fragile and I find it broken on most 8i's I encounter in the field. It is also difficult to get the cord fully back in the arm without interfering with the attachment of the hand controller.
So, though it is not as light, I recommend the C8-SGT instead. It has none of the 8i's flaws.
But if you are going to use this as a "grab'n'go" scope, a temptation with a scope this lightweight, don't! An 8" SCT doesn't cool down fast enough to give you thermally equilibrated images in a short time. And if you can leave it out for an hour first, then there is no disadvantage to the heavier C8-SGT.
Just a different point of view than the author's. I still think he will enjoy the scope, flaws notwithstanding.
--------------------
Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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BigCaT
super member
Reged: 12/14/05
Posts: 136
Loc: Quebec, Canada
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Hi Don,
I agree with you about flaws you mentioned except for the #3. Correct me if i'm wrong, but this is not the case for every C8 since the orange OTA of the Nexstar 8i is exactly the same than the black OTA on SGT? An according to this reference: http://www.sctscopes.net/SCT_Tips/Eyepieces/eyepieces.html , the maximum field of view that is possible to get with a C8 is 1.07 degrees because the rear-cell opening is 1.5" (I'm curious to know the math behind that)
--------------------
Felix
Nexstar 8i SE
Antares 127mm F/6.45
30mm, 12.5mm, 10mm Celeston Ultimas
17mm Baader Hyperion
7.4mm TeleVue Plossl
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jeffk1965
sage
Reged: 05/02/04
Posts: 333
Loc: South Florida
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Hi,
I own both a Nexstar 8i-SE and a C11S-GT. The N8i is much easier to set-up than the ASGT mount that comes with my C11. I leave the scope set-up in my closet and just carry it outside in one trip. The ASGT requires at least one trip for the mount, one for the ota, and possibly an additional trip for the counterweights. Then you must attach the ota to the mount, align it north (polar alignment is not necessary for visual), and put on the counterweights. Then you must align the scope to three stars. It is a lot more work but the ASGT mount works well and tracks nicely. The N8i sets up super fast and I am using it as super fast quick set-up scope. I can literally take it outside, put it down, turn it on, align to three stars and observe all in one trip with a second trip for my eyepieces and chair.
The only difference I have found between my N8i and the one reviewed is my tracking is not as good and I must center the object using the up and right arrows for it to track properly. Once the object is centered in this maneer, it tracks okay.
Clear skies,
Jeff
C11S-GT
Tec140
N8i-SE
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asaint
Carpal Tunnel
Reged: 04/25/03
Posts: 2072
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Don,
I don't agree with #3. I used a William Optics 2" SCT diagonal without any problems. It cleared the base just fine. I also used a huge 35mm Panoptic without any noticeable strain on the motors or any FOV creep.
The lack of manual controls drives a guy like me nuts. :}
Allister
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spaceydee
Postmaster
Reged: 04/16/04
Posts: 15872
Loc: Where the Kittens Are
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I'll agree that if you care about tube cooldown, you'll be waiting a while! 
--------------------
Dee
space-scientist
student violinist
Nexstar8i,SV80S,80/9D,FC100,94 Brandon,TMB92SS,GM8
8" f/7 Discovery,12.5" Portaball, PST
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 11748
Loc: Los Angeles
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Quote:
Hi Don,
I agree with you about flaws you mentioned except for the #3. Correct me if i'm wrong, but this is not the case for every C8 since the orange OTA of the Nexstar 8i is exactly the same than the black OTA on SGT? An according to this reference: http://www.sctscopes.net/SCT_Tips/Eyepieces/eyepieces.html , the maximum field of view that is possible to get with a C8 is 1.07 degrees because the rear-cell opening is 1.5" (I'm curious to know the math behind that)
Maximum FOV is 57.3 * (27.0mm of eyepiece field stop/2032mm telescope focal length = .76 degrees. Allowing for vignetting visibility, this goes to about .85 degrees.
With 2", and a 38mm opening in the baffle, the max.FOV is 1.07 degrees, and allowing for the visibility of vignetting, this stretches to about 1.2 degrees.
The 8i is not usable, unfortunately, with most 2" diagonals, even the shorter, threaded on, SCT diagonals (except the 2" SCT diagonal from William Optics, which clears the scopes I just tested it on by about 1mm).
Celestron's other scopes all have more clearance between the base and the tube. (The GEM one has no clearance problems at all).
Don
--------------------
Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 11748
Loc: Los Angeles
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Quote:
Hi,
I own both a Nexstar 8i-SE and a C11S-GT. The N8i is much easier to set-up than the ASGT mount that comes with my C11. I leave the scope set-up in my closet and just carry it outside in one trip. The ASGT requires at least one trip for the mount, one for the ota, and possibly an additional trip for the counterweights. Then you must attach the ota to the mount, align it north (polar alignment is not necessary for visual), and put on the counterweights. Then you must align the scope to three stars. It is a lot more work but the ASGT mount works well and tracks nicely. The N8i sets up super fast and I am using it as super fast quick set-up scope. I can literally take it outside, put it down, turn it on, align to three stars and observe all in one trip with a second trip for my eyepieces and chair.
The only difference I have found between my N8i and the one reviewed is my tracking is not as good and I must center the object using the up and right arrows for it to track properly. Once the object is centered in this maneer, it tracks okay.
Clear skies,
Jeff
C11S-GT
Tec140
N8i-SE
But the 8" SCT makes a poor "grab'n'go" scope because of its cooling. So the SGT takes longer to move and setup. Take the tube out first and let it start cooling.
[Actually, I own an ASGT mount for my Mak, and I carry it outside as an assembled unit and take the tube out separately. The 38 lbs of the mount is very easy to lift and carry unless you have a bad back].
--------------------
Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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jason_milani
Carpal Tunnel
Reged: 09/03/04
Posts: 1626
Loc: Northeast Ohio
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I have not owned a Nexstar 8 but HAVE had a Nexstar 5 and i'm sorry i got rid of it. I also have owned an AS-GT mount and used it with various refractors. I will second the fact that there is NO comparison in setup time when comparing the Nexstar to the AS-GT. The Nexstar (in my opinion) really IS grab-n-go while the AS-GT is NOT. I got rid of it for just that reason. I always looked at the nexstar 8i with curiosity as a great balance between aperture and portability and think the author summed it up well. I have a question about the handling of the mount/scope combo, though. On the Nexstar5 there was no problem grabbing it from the case with one hand and setting it on the tripod. The 8" has no handles and i was curious to find out if it is awkward to lift the scope and mount it on the tripod. Thanks for the reply. I do NOT mean any disrespect to starman1 on his observations as everyone has a preference and that is why this site is such a great source for information. I'm just not crazy about a German equatorial as a "quick look" type of scope. I've owned a few and that is just not my cup of tea, so to speak.
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Celestron C-9.25 XLT
Orion/Vixen ED114SS Refractor
William Optics Megrez 72mm Refractor
Orion Atlas mount with EQ MOD
Half Hitch Mark I w/Sky Commander
Mallincam Hyper Color Plus
Celestron Neximage
Baader UV/IR Modded Canon 40D
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spaceydee
Postmaster
Reged: 04/16/04
Posts: 15872
Loc: Where the Kittens Are
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Don, do you think that the cooling issue is only true for planets, or for other targets as well?
I like my 8i, and think it's convenient but I will not argue with your assessment of its weaknesses.
--------------------
Dee
space-scientist
student violinist
Nexstar8i,SV80S,80/9D,FC100,94 Brandon,TMB92SS,GM8
8" f/7 Discovery,12.5" Portaball, PST
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 11748
Loc: Los Angeles
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Quote:
Don,
I don't agree with #3. I used a William Optics 2" SCT diagonal without any problems. It cleared the base just fine. I also used a huge 35mm Panoptic without any noticeable strain on the motors or any FOV creep.
The lack of manual controls drives a guy like me nuts. :}
Allister
The 2 units in the shop crept down with that much weight on them. You must have gotten a tighter clutch. That's great, but I have a different experience. As I said in an earlier post, the WO 2" diagonal clears by 1mm, but other 2" diagonals do not.
--------------------
Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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jeffk1965
sage
Reged: 05/02/04
Posts: 333
Loc: South Florida
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I live in South Florida and cooling is not too much of a problem here.
Regardless of the cooling....the N8i-se is significantly easier to set up than the ASGt mount.
jeff
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jeffk1965
sage
Reged: 05/02/04
Posts: 333
Loc: South Florida
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The N8i-se is easy to lift and carry while on the tripod. I leave it attached to the tripod so it can be carried out in one piece.
It is a little tricky lining up the holes when attaching the scope to the tripod but it is not too bad. It is not difficult to lift the socpe up as it is only about 25lbs.
Luckily, the scope is so compact when attached to the tripod that I can store it while attached to the tripod in my closet.
jeff
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 11748
Loc: Los Angeles
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Quote:
Don, do you think that the cooling issue is only true for planets, or for other targets as well?
I like my 8i, and think it's convenient but I will not argue with your assessment of its weaknesses.
Dee,
From my 11 year experience of owning an 8" Meade, I found the tube will reach thermal equilibrium after about 3 hours unless active cooling is used, in which case 1 hour or less is possible.
I should add my normal viewing experience is for a 30 to 40 degree temperature drop in the first 90 minutes after sunset. In an environment where the temperature drop is minimal, the scope may come to equilibrium sooner.
Gauging thermal effects and differentiating them from seeing artifacts is a matter of experience.
Suffice it to say, whether active cooling is used or not, an 8" SCT is not a good candidate for "grab'n'go" use.
I am not against the 8i per se, as a scope. I think it is quite good optically. I just wanted to point out that there is an option at/near that price point for the observer interested in imaging and heavy accessories.
--------------------
Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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spaceydee
Postmaster
Reged: 04/16/04
Posts: 15872
Loc: Where the Kittens Are
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I agree with you, I guess I wouldn't consider an 8" SCT grab and go.
--------------------
Dee
space-scientist
student violinist
Nexstar8i,SV80S,80/9D,FC100,94 Brandon,TMB92SS,GM8
8" f/7 Discovery,12.5" Portaball, PST
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BigCaT
super member
Reged: 12/14/05
Posts: 136
Loc: Quebec, Canada
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I agree! This Winter (not the winter of CA) , it is more a grab...wait, and wait and go for a two hours of a very cold session!
This is something than I like with this N8iSE, GOTO and tracking work very well at -20 celcius!
--------------------
Felix
Nexstar 8i SE
Antares 127mm F/6.45
30mm, 12.5mm, 10mm Celeston Ultimas
17mm Baader Hyperion
7.4mm TeleVue Plossl
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John F Smith
newbie
Reged: 12/20/05
Posts: 3
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Hi all,
I'm don't necessarily agree or disagree with many of the mechanical problems that Don has cited in his reply to my review, except that I agree that a 2" diagonal is a poor choice for this scope, and that the scope will not turn in Azimuth manually.
As far as cool down is concerned, I store mine covered in my garage which stays within about 5 degrees of ambient outside temperature, so cool down is not an issue for me.
I would certainly agree that this is not a scope for imaging; it simply doesn't have the robust mount needed for imaging of virtually any kind. But, as I have no interest in the thousands of dollars and hundreds (or thousands) of hours required to learn and get good at imaging (as cited by Rober Bruce Thompson in "Astronomy Hacks"), that is not an issue for me.
In fact, I wouldn't want to put much weight on it at all without perhaps adding Ray's Brackets. That's why I'm using my 24mm 1 1/4" Panoptic at 85x as my low power eyepiece and it suits me just fine.
I've had it out a second time now, and everything that I mentioned about the ease and precision of the GOTO and tracking on this scope has held true.
I'm a very happy camper.
John F Smith
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jeffk1965
sage
Reged: 05/02/04
Posts: 333
Loc: South Florida
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Hi,
Here is my observing report from tonight with my Nexstar 8i-se:
I was out in my front yard tonight in South Florida, with my Nexstar 8i-SE. I observed for 4-hours (from 9:30PM to 1:30AM). The seeing was very good, around a 7. It was in the low 60s with no wind. I started off with Saturn and then went to the moon which was near full. Saturn looked very good and held up well at high powers. I was able to obtain consistently sharp views at 286x (7mm Nagler) and very good views at 333x (3-6 Nagler Zoom at 6mm) and views that were still decent at 400x (5mm Nagler). Cassini’s Division was seen around the entire planet and the ball of the planet was nice and sharp with a light band on the planet. The A, B, and C rings were visible. Next came the moon and even though it was near full, I was able to see 4-craterlets in Plato as well as some nice views of the Cobra Head. I split the following double stars tonight: Almach, Rigel, Castor, Beta Mon, and Polaris. I then viewed quite a few Messier Objects, mainly to test goto accuracy as the moon was full and some of them were a bit washed out. Nevertheless, the open clusters still looked very nice. I viewed: M34, M35, M36, M37, M38, M41, M42 (6-stars were visible in the Trapezium), M46, M47, M48, M50, M79, M81, M82 (barely visible), M93, as well as the Double Cluster. I also took a look at Caldwell 59, the Ghost of Jupiter, and was surprised to see that it was easily visible even in the moonlight sky. All of my gotos were very accurate and the Sky Align system works very well. Tonight was a fun night.
Clear skies,
Jeff
C11S-GT
Tec140
N8i-se
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DCS
professor emeritus
Reged: 12/03/05
Posts: 641
Loc: Cypress, Texas
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I've had a NexStar 8 for about 3 years - I respectfully don't agree with many of the things being said here. Granted, it's not a perfect design, but it's not as bad as it's being made out here.
Quote:
The altitude clutch doesn't lock. Heavy accessories can cause the altitude to "creep".
Although it's certainly true the alt clutch is friction only, I've hung a reducer, visual back, and (reasonably heavy) DSLR off the back with no indication of it giving away - tracked nicely on the wedge for long exposure as well (although admitedly not as nicely as my Losmandy GM-8 does).
Quote:
The scope is not usable with a 2" visual back. On a 6" or smaller scope, this is not a problem. But the 8" SCT's maximum field of view is ONLY achievable with a 2" diagonal and 2" eyepiece. So the FOV is restricted to .8 degrees or less. There isn't even room for a focal reducer between the scope and base.
I would not say it is unusable with a 2" VB. I've done this, as well as a 2" diagonal when I was using some 2" wide angle eyepieces that I borrowed. Targets near the zenith become questionable due to the clearance issue though.
Speaking of which - the clearance problem is a very real one. I understand that there is a product out there to fix this (Ray's bracket - http://www.buyastrostuff.com/store/n8_page_1.htm - but I have mental problems spending more money on something that should not have been a problem to begin with. I've toyed with the idea of pulling the 8" OTA off of the NexStar "arm" and mounting a Losmandy dovetail on it - then a Losmandy saddle plate to the NexStar arm (the latter part needs more thought on how the adapter would work). Anyway - that way I could slide the OTA up and down on the arm for clearance / balance and as an added bonus I could pull it off with the twist of a knob and mount in on my GM-8 when I felt the desire to do so. Has anyone done this before? 
Quote:
But the 8" SCT makes a poor "grab'n'go" scope because of its cooling. So the SGT takes longer to move and setup. Take the tube out first and let it start cooling.
Where I am (SE Texas) cooling is not too big of an issue - even then I can carry the NE 8 outside in one hand (leaving a hand free to open the door) and place it out on the back patio an hour or so before my session. The (forgotten) other side of the grab-n-go equation is pack up when you're done. You can hold a NexStar 8 in one hand while holding the tripod (I've got the heavy duty model) in the other and head in. The batteries in the base facilitate this - although I've moved on to a power tank because dealing with 8 AA batteries is a pain.
Even better - on a recent week long trip to a river house in Llano, TX (really nice dark skies) I stored the N8 intact on its wedge and tripod on a back patio. When darkness came, I could carry the entire assembly out to a desired spot at commence observing right away. I could probably do this on the back patio at home as well - if it wasn't crowded with all the non-astronomy items.
Quote:
The plastic plate the hand controller hooks on to keep it in the arm is very fragile and I find it broken on most 8i's I encounter in the field.
Mine is still intact - I wasn't aware of its tendency to break - I'll take a closer look at this next time I'm out (could be tonight). I've never noticed that before.
At days end - I've really enjoyed this scope. The views are first rate, it sets up quickly, the drives are not abnoxiously loud, and the goto works well. For photography you may want to think twice as clearance and drive backlash (the DEC drive is particularly bad) will frustrate to no end. Even then I've managed some pretty pictures through it on a wedge. 
-Pete
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