SCT focuser. Electric or feathertouch ?

[DENMONKEY]

Question is pretty much as it says on the tin.

I'm looking to improve my ability to fine focus on my recently acquired C8.
I'm really quite happy with the scope in general without having a great deal to compare it to and am pleased with the results when I manage to get a subject in 'good' focus.

The issue is that sometimes I am finding it hard to hit that sweet spot without a lot of back and forth searching.
I may be slightly over exaggerating the effort required but I think either of these products may offer a simple solution.

The question is which one ?

Whilst I like the concept of an electric focuser I think I would prefer the manual option to avoid any additional wires or the requirement for more batteries.
KISS right ?

The feather touch focuser looks like a brilliant piece of kit not only from a aesthetic point of view but from the reviews I've read a micro focuser of some description is a must have add on.

Anybody with any experience with these specific focusers on a SCT ?

Aso a 'local' supplier has an electric focuser priced at near $600 :eek:but I have seen them sub 200 from OS sources.

The FT focuser I believe can be had for around the 150 mark but again from OS.
Are there any local suppliers that can be recommended ?

Cheers in advance.

Brett


oops quick edit

Im refering to this type

http://starlightinstruments.com/shop/images/FMCEL-C-8.jpg

not this option which I beleive to be for a reflector but have seen them used on the SCTs too

http://starlightinstruments.com/shop/images/2008DSBCRcr.jpg

[acropolite]

Brett, I have a feathertouch on my LX90 and it is fantastic, the difference is amazing. I found that the old focusser, once released, usually changed focus, the feathertouch has much better tolerances and because the fine focus requires only the lightest touch it's not prone to shift once released.

IMO the best accessory I have put on my LX. :thumbsup:

[gbeal]

Brett.
I have not used a Feather Touch on an SCT, as I don't own an SCT, but I do own a F/T, three in fact. While it may be difficult to comprehend paying more for a focuser than a scope costs, in some cases it is the single thing that makes an average scope much much better.
In your case, the "Micro" which supersedes the focus knob will be better, but not the magic bullet you seek. What you need is the full monty which you link to and have decided you don't want or need. Why? In the case of most SCT's mirror flop will annoy the pants off you, and really the only way to eliminate this is with an external focuser, sorry.
Let me add that once you get one of these, the next best thing is the digital drive unit, so motorized focusing, or with applicable software, automated focusing. Wonderful stuff.
The F/T stuff is not cheap, but in the optical world you normally get what you pay for unfortunately.
Gary

[DENMONKEY]

Thanks for the quick replies guys.

Seems the verdict is in and thus far as the reviews have suggested this is a good move.
Just wanted to get some 'real' feedback from real people.
So cheers for that.

While I'm at it Phil cheers for the quick post on the item I picked up from you a few weeks back. Haven't used it yet but will soon.

GB the reason I was leaning towards the micro was I'm using a fork mount and have concerns around the clearance area between that style of focuser and the mount etc.
Once a diagonal is added I fear it simply won't it to pass through as such.

I understand the concept of mirror flop but thus far haven't noticed it I don't think but since I'm so green maybe I'm just not aware of it.
From what I can tell once I'm focused there doesn't appear to be any movement of the mirror or change in the visual focus it is just sometimes a tedious exercise to get it spot on.

I might be being a bit particular here but when I can achieve pin point sharp stars it's hard no to want make that a repeatable achievement every single time:D

[gbeal]

Hi Brett,
OK, for visual only, the micro will likely suffice, and if you haven't noticed any mirror shift then the "extra" focuser may be an overkill.
For imaging though I would recommend the whole shebang.
You do raise a valid point though, the clearance through the forks. Can't help you here, maybe write direct to Starlight and ask them, it is something they will likely know.
Gary

[DENMONKEY]

Just a quick update, which I think has settled the decision and might assist anyone else considering similar options.

I stumbled onto this review
http://www.cloudynights.com/item.php?item_id=72

which states "As I'd expected, on the other hand, I couldn't reach focus with any eyepiece when I screwed my f/6.3 reducer - corrector onto the rear cell."

Since I've recently acquired a focal reducer and am considering a new 2inch diagonal it appears I would certainly encounter clearance issues when using the reducer, focuser and diagonal all at the same time :(


Looks like the feathertouch microfocuser is the way to go.

[Merlin66]

I use the #1206 and the zero shift #1209 on 10" and 12" LX200.
They do an excellent job. Why would you want to change???

[DENMONKEY]

Thanks. Hadn't seen those. Appears an interesting option though, albeit the price is in excess of those options I was looking at.

I'm not sure if they would result in the same difficulty in focusing when having all the gear attached at once due to the increased distance of the EP to the primary.
Any advice on this one ?

[asterisk]

Hi Brett

I replaced the focusser on my C8 SCT with the Feathertouch. I completely agree with Phil - one of the best accessories I have installed.

I can't help you with the clearance question - mine is on an Eq mount.

Cheers

[wasyoungonce]

I've just ordered a GSO SCT 10:1 focuser for my C8. So, I cannot comment on how good it is but from what I have read on the internet & this site...they are OK.

I gave up with the stock focuser when trying to image Jupiter with a 2X barlow at prime focus with a SPC90NC web cam. I tried every trick to reduce this image shift.

The image would pretty much shift 1/4 of the CCD FOV (which is actually a pretty small FOV in anycase) when trying to focus. All very frustrating.

And...I'm too poor for mega cost addons.:sadeyes:

[GrampianStars]

G'day Denmonkey (Brett)
http://starlightinstruments.com/shop.../FMCEL-C-8.jpg
Yep put this on the LX20012" its a beaut together with the std electric focuser and "the mirror locking mirror bolt" :thumbsup: will help as well

[g__day]

I have both on my C9.25 . I have a Feathertouch micro focuser and a Meade motorfocuser hooked into a JMI serial -> USB convertor into software that runs the focus motors.

With a Bhatinov mask - getting focus for visual work is child's play. Too the Feathertouch reduces mirror shift by a significant factor. Without it when I changed direction of the focuser a star might jump a degree or two around the eye-piece! With the Feathertouch its less than one third of this movement.

Once I have close focus I simply snap a series of shots and focus in and out (using the Meade focuser and moving the focus point by microns I suppose). I then inspect the resulting picture of the Bhatinov masked star, looking whether the central spine is a pixel or two low or high. Generally I prefer to not touch the scope at all when its doing anything related to imaging - including the focus set up.

My thoughts,

Matt

[Bloodbean]

Interesting thread with lots of good information. Can anyone comment on how difficult it is to install a Feathertouch microfocuser on a C8?

Thanks,

Troy

[asterisk]

Too easy - takes about 5 minutes. The instructions for the C8 microfocusser are available here:

http://starizona.com/acb/instructions/C8%20Focuser.pdf

As well, there is a video clip:

http://starizona.com/acb/videos/Feathertouch/Feathertouch.html

If you are planning on installing one, follow the instructions and take it slowly.

[DENMONKEY]

Beat me to it Geoff.

I just copied the link as you posted.

That vid makes it look like a cake walk to get installed.
Really is a 5 minute job.

As far as add-ons, this thing is never going to end is it :( :D

Thanks everyone for the assistance in this matter.

Beers for everyone

[AlexN]

on my C11 I use a moonlite focuser.. they are not quite a feathertouch, but they are not quite the cost either :) I find my moonlite to be leaps and bounds over the standard focuser, however I'll probably upgrade the standard focuser to the feathertouch micro in the future also....

SCT focusing can be a BIG pain in the butt.. however once you have an external crayford on it, you'll love the scope to bits..

Alex.

[asterisk]

Sorry

The vid didn't exist when I did mine, and the instructions missed out one vital step. Luckily there were IIS members who had gone before - Matt helped me out a lot.:):)

[marki]

I use a moonlight with stepper motor and cercis controller on my LX200. Very repeatable focusing and works well in maximDL when using CCD. Not very good for visual work as it is too slow ( I am an impatient sod).

Mark

[AlexN]

Mark, I too find the moonlite too slow for visual work, however during visual observation I find the SCT standard focuser to be fine... but for CCD work the motorized moonlite is utterly brilliant...

Alex.

[marki]

Hi Alex

The controller is a bit big for visual as well. No probelm though as I use a little 80mm refractor on the HEQ5 pro when I want to do some visual observing in any case. Just ordered a little zenithstar 66 which should be even more portable and will make a great guidescope/superfinder for the LX as well.

Mark

[wasyoungonce]

Well ..I've got my GSO SCT 10:1 focuser.

It needed quite a bit of fiddling to get it right:
http://www.backyardvoyager.com/gsofocuser.html.

It is better now but not as good as I expected..a bit hard to tell as its too smokey outside to try out the C8.

I've adjusted it quite a bit and it feels pretty good now....time & use will tell.

It is obviously not feathertouch quality..and not feathertouch cost as well.

[toc]

Hmm - I think this site got hacked...

http://www.backyardvoyager.com/index.html

[Damian Couzoff]

Hi alex, I second that,l have a Bintel 10:1 SCT 2 inch Crayford focuser,on my Celestron CPC 1100-11 inch Schmidt Cassegrain.It only cost $119.I do the coarse focusing with the primary first,then use the fine focus on the crayford,then lock the crayford.l have added a losmandy bottom dovetail,with the special 1 kg counterweight,and balanced to suit,with the Crayford,2 inch quartz diaganol,and my heaviest 2 inch eyepiece in my kit.The crayford screwed straight on the back,l am happy with the crayford and the CPC 1100;).Regards damian

[Merlin66]

I have a feathertouch 10:1 on the C9.25 - works great!
For the C11 I fitted a SW motor via a small timing belt to the existing knob - now I can control the focus either from a handcontroller or via USB.
BTW the image "slop" during reverse focusing at f10 is less than 4 pixels!

Also, the CFZ ( depth of focus) for 1/4 wave accuracy on a f10 system is 0.22mm (220 micron) - this should easily be obtained with any focuser.....