Electric Focuser for Celestron NexStar 130 SLT Scope (Full Version)

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Arthur Dent -> Electric Focuser for Celestron NexStar 130 SLT Scope (5/10/2008 9:31:40 PM)

Hello everyone!

First post so - be gentle!

Just purchased a Celestron NexStar 130 SLT telescope.  Had a brief play on Friday night (yesterday was wet & windy).  Apart from the annoying mm/dd/yy format on the setup I got some good views of Jupiter.

However, using a 4mm eyepiece, I found it virtually impossible to focus the scope properly because of the "bounce" of the telescope caused by my hands on the manual focusing knob.

I know that there are some electric (electronic) focusers for other scopes but don't know of any for mine.

If anyone can offer any help with/or has experience of a replacement focuser or attachment ( the JMI motofocus seems a bit of a "bodge" ?) to overcome this problem I'd be most grateful.

Many thanks for reading this far and I look forward to any replies/suggestions.

Thanx

Art



brianb -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (5/10/2008 10:17:47 PM)

Welcome to the forum!

I don't have any direct experience of replacement focusers on that particular scope but the JMI focusers are good.

BTW I have difficulty focusing a 4mm eyepiece full stop. Especially on Jupiter this year ... the poor seeing caused by the low altitude makes anything higher than about 15mm simply not worth the effort.



dellboy -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (5/10/2008 10:56:56 PM)


The answer is not 42
but when using that much power you will need to get close to focus and then a feather touch a little at a time
also depends on your mount!!



Arthur Dent -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (7/10/2008 8:31:37 PM)

Thank you brianb for your reply.  Yes the seeing was poor on Friday.  Although there were basically some "clear" spells, there was actually quite a bit of high altitude cloud which smeared out all details on Jupiter - even with a 15mm eyepiece.  As you also said, Jupiter's low altitude also doesn't help.  I just couldn't wait to play whit my new purchase however.

dellboy - I generally find that the answer is 42 (at least to 1 d.p.)!

The mount is Celestron's standard GOTO Alt-Az mount for that scope.  When trying to focus using the 4mm eyepiece, there was so much "bounce" (and then subesquent vibration which only died away after about 5 - 10 seconds) that I found it almost impossible to get as sharp as focus as possible.  However, the seeing wasn't particularly good and 4mm eyepiece was basically too powerful.  Even at 15mm, details were somewhat "smeared out".

It made me realise however, that even though the seeing was poor, the vibration in the scope at that magnification made me think of an electric focuser - hence my query.

Thanks for the replies so far.

Anyone else have any ideas/suggestions?

Art



dellboy -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (7/10/2008 10:06:58 PM)

Brian
I have an 8" newt
have changed the focuser twice so far on it.
It came with a rack & pinion focuser to start with, was okay for low power visual but too much play when i started to try astrophotography.
I then brought an dual speed Crayford style focuser from telescope house ,this was a great bit of kit for visual observing, but because of the change in profile I could no longer reach focus with DSLR.
In the end i brought a focuser from "moonlite focusers" in the states it cost me quite a bit,but it has been well worth it.
it is a manual one but you can get electronic ones & they are now available in the UK.
Dell



Arthur Dent -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (9/10/2008 1:08:48 AM)

Thanks for the advice dellboy

I'm not sure that I'm going to go down this route though.  I'm already considering upgrading the scope (I've only had this one a week!) to a Cassegrain-Schmidt such as Celestron's NexStar 5 or 6SE.  I'm finding the NexStar 130 SLT a but bulky TBH.  The lounge is kinda dominated by the tripod and OTA so looking for something that I can pack away quite quickly in between observing.  Also thinking about transporting to my friend's house in the depths of the Welsh countryside where dark skies abound!

I'm really keen to get into astrophotgraphy and would like to know if there are suitable electric focusers for these scopes.

Art



meggsy -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (23/10/2008 12:46:16 AM)

Hi Arthur Dent, I've got the scope as you do, I find a 6mm eyepiece is what I use for Jupiter and saturn, I live in oz, but I find the best time to see plants, (well thats me) is when they are above ours heads.



Arthur Dent -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (26/10/2008 1:04:08 AM)

quote:

ORIGINAL: meggsy

Hi Arthur Dent, I've got the scope as you do, I find a 6mm eyepiece is what I use for Jupiter and saturn, I live in oz, but I find the best time to see plants, (well thats me) is when they are above ours heads.

G'day Meggsy!

What part of Aus?  My Uncle is in Perth, WA (but my heart belongs to Sydney).  Views of the Milky Way from Yulara (Ayres Rock Resort) were awesome!  BTW by "plants" I presumed that you meant "planets"?

I have tried a 25mm and 9mm for alignment and viewing (and have been impressed with views of the Moon but not of Jupiter).  Mind you, apart from the fact that the eyepieces say "Celestron" on the side, I have no idea what kind of eyepiece they are (Ramsden, Kellner, Abbe, etc).

My problem is not so much viewing as getting the scope to a) align and b) GoTo and object successfully!

Art



brianb -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (26/10/2008 4:39:10 AM)

quote:

apart from the fact that the eyepieces say "Celestron" on the side, I have no idea what kind of eyepiece they are (Ramsden, Kellner, Abbe, etc).

Very likely Plossl. Especially if the longer ones have the eye lens recessed into the eyepiece body.




Astro_baby -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (26/10/2008 11:58:02 AM)

I have the Nexstar 4SE ( recently acquired as a grab and go scope to complement the big 'un ).

If your having alignment and GoTo hassles then the problem may be power.  Does your 130SLT  run off batteries ?  If so then that may well be the cause.  The 4SE has a battery capability but I have been told running off batteries often causes GoTo glitches on Celestrons smaller stuff.

Regarding the focuser I have a Moonlite Dual Rate focuser and thats as smooth as you can get, its attached to an 8" Newtonion thats mounted on an HEQ5 mount - thats a VERY solid combination and even that wobbles when a 4mm is plugged in.  Maybe its not as wobbly as your mount but theres still wobble.  Bear in mind a Moonlite and adapter kit cost almost as much as your entire scope.

There is an electric focuser option from Sky-Watcher but it wont fit any scope smaller than the 150 as the 130 scope has a different focsuer to the rest as far as I know.  To be honest I doubt an electric focuser would give you much benefit.

Dont forget the maximum magnification that can usually be usefully acheived is around x200 in the UK due to the seeing conditions and quite frequently well below that.  I am assuming that the 130 SLT is identical to the Sky-Watcher 130 with a focal lenth of 650mm.  That with a 4mm EP will generate a magnification of x162 - which is very high especially for an object like Jupiter whic is low on the horizon and therefore your looking through the thickest bit of the atmosphere with all the crud and heat haze.

Recently I was out in a completely dark sky environment that was close to ideal and even then with Jupiter being so low I couldnt get beyond about 8mm on the EP and mostly spent the time with a 15mm in to look at it.




QuietQuackers -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (26/10/2008 4:24:54 PM)

quote:

ORIGINAL: dellboy


In the end i brought a focuser from "moonlite focusers" in the states it cost me quite a bit,but it has been well worth it.
it is a manual one but you can get electronic ones & they are now available in the UK.



Could I ask which focuser you bought from Moolite as I'm after one myself but not sure which size drawtube to get to focus my 350D on my C8-NGT
Thanks



Abo -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (10/12/2008 10:13:33 AM)

quote:

ORIGINAL: Astro_baby

If your having alignment and GoTo hassles then the problem may be power.  Does your 130SLT  run off batteries ?  If so then that may well be the cause.  The 4SE has a battery capability but I have been told running off batteries often causes GoTo glitches on Celestrons smaller stuff



I agree with this comment; I was running my SLT off AA batteries and the goto was pretty flakey. I bought one of these:

http://shop.eurobatteries.com/adapter-ac-to-dc-p-1258.html

Powers the scope just fine, once the alignment is sorted it tracks for ages with no drift and the goto is very accurate.

Looking at a powertank now for trips to dark sites...



wombat -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (10/12/2008 11:08:40 AM)

hi, have a look at switched systems (if they are still in business) for the motofocus. try hanging some weight from your tripod to help stability. i'd be going for either a powertank or if your close enough to mains a 12v transformer [:)]



Abo -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (10/12/2008 11:42:34 AM)

quote:

ORIGINAL: wombat

hi, have a look at switched systems (if they are still in business) for the motofocus. try hanging some weight from your tripod to help stability. i'd be going for either a powertank or if your close enough to mains a 12v transformer [:)]


Ian Morrison suggests putting a sandbag on the tripod spreader, the extra weight does help.



1981astro -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (25/12/2008 7:50:11 PM)

Hello,

do you really find the 130 bulky?  That's small considering other Newts, I went from a 102SLT (refractor) to a C8N (reflector) and couldn't believe the size difference!!!  NOW the tripod dominates a room!
I'll have to dig the photo out on here of both scopes side by side, then you can worry (the 130SLT tripod is the same as the 102SLT)


I used the one from Switched Systems, they were very helpful and the chap was more than happy to email me to make sure everything was OK.

You will struggle with a 4mm EP on the 130 TBH.  Can't remember the maths but I'm sure the maximum to use would be a 6 or 9mm.  Even a 4mm on my 8" newt is hard work!
An electric focuser won't really help on this, it's all down to the tripod.  You could be stood completely still, f*rt, and then wait 5 minutes for the vibration to disappear; the point is the tripod is that sensitive - when I was looking to modify mine, I came across a number of sites that suggested extra weight to the tripod, the best being filling the legs with sand, as previously suggested.



1981astro -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (25/12/2008 7:57:21 PM)

Also;

quote:

Could I ask which focuser you bought from Moolite as I'm after one myself but not sure which size drawtube to get to focus my 350D on my C8-NGT



You can use any crayford, however you will need to use an extension tube to reach focus with the DSLR.  I got a cheap Crayford, possibly upgrading to a better one at some point, but in the meantime I use a 2" extension tube on the focuser with the camera attached to this and I now get focus OK.

Or go for a low profile one like this: http://www.telescope.com/control/product/~category_id=focusers/~product_id=08881



Astro_baby -> RE: Electric Focuser for Celestron NexStar 130 SLT Scope (26/12/2008 4:46:00 PM)

My Moonlite is the dual rate focuser with tri screws as per HERE The drawtube is the standard length of 50mm.  I went with Steve at FLOs advice on this and its worked fine so far.

I had mine ordered specially in black and I have to say it works like a charm and looks the business too.  The finishing on these is amazing.

One thing you may well have to consider when fitting a Moonlite is they are quite heavy - for me it meant an extension bar for the weights as it pulled the scope past its balance point with the standard weight bar on an HEQ5.

Its a beautiful bit of kit though.



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