SCT Focuser Opinions/Recommendations

[issdaol]

Hi All,

I am looking to get a new focuser that attaches directly to the 3.25 inch flange on the back of my Celestron SCT CPC1100.

I am looking at:

1. JMI - EV
2. Feather Touch
3. Moonlite

All three can do this and all three seem to be great focusers but I have not used any before.

I would appreciate any comments/opinions/experiences (or alternatives) that anyone has to offer.

Cheers

[marki]

I have used the EV-1 and moolight focusers on my mead LX200R and have a feather touch 10:1 micro focuser on the main mirror focus. I was not happy with the performance of the EV-1 and changed to the moonlight crayford....enough said. The moonlite crayfords are as solid as a brick and are great for AP in the correct configuration (mine has a stepper motor and is driven by the moonlite controller giving perfect repeatability) and will support very heavy loads without problems such as flex, tilt etc. I also have a 2 speed moonlight on my refractor and am very pleased with the smoothness and lifting capacity of the unit (rated to 3.5kg or there abouts). That said I imagine you would be equally happy with the feather touch and people really rave about their qualities. It really depends on your intended use.

Mark

[AlexN]

I had a moonlite on my C11 and it was extremely good quality.. Mine was the DC motor version, a step down from Mark' model.. It was fantastic...

I've got a 2" FT on my APO at the moment, I'm having some issues with it and with my heavy camera setup, bit of sag..

The quality of the FT is pretty amazing, and it feels siillllky smooth.. but considering its not doing what I bought it to do, I will say I'm a little peeved with it...

[issdaol]

Hi Mark and Alex,

Thanks for the comments.

I am primarily using my CPC1100 for visual but have been experiencing mirror movement at fine focus which is rather annoying so primarly the focuser would be to provide fine visual focus.

I also have a new Canon 5D Mark II so was looking for a focuser that could support that at prime focus as I am starting to get interested in Astrophotography.

The moonlite does look like a solid unit can the drive version be manually focussed?? Or does it rely on the hand crontroller if you have a drive?

Interesting to hear about the feathertouch. Is that drawtube sag??

Cheers

[marki]

Gee Alex, thats the first negative comment I have ever heard about the FT..... new owners cutting corners????. My imaging train must weigh at least 2kg and with the 2 speed moonlight on the refractor racked out close to 100mm (sweet spot) I still notice no tilt or sag. The draw tube for the LX200 is much shorter and I could swing off that. The moonlites are built like tanks but they are also very heavy which may cause balance problems and add extra strain on the mount.

Mark

[marki]

Once the motors are mounted the units cannot be focused manually. If you are mainly doing visual with the occassional snapshot then the 2 speed manual focuser will be more then you need. It will not correct mirror flop though and you will need to find a way to lock the primary (meade LX 200 tubes have this built in). You might also like to have a look at these.

http://www.optcorp.com/product.aspx?pid=105-175-1041-8939&kw=&st=0

I have one and it does work much better then the standard setup. If you decide to get the moonlite make sure the draw tube comes with a brass clamping ring (has three thumbscrews to attach diagonals, camera's etc) as the standard draw tube (single thumbscrew) is not good enough IMO.

Mark

[gbeal]

I'll toss in my preference for the F/T, but take on board the comments made by Alex. Possibly it depends on the loads you have or think you will encounter.
In Alex's case, maybe a bigger F/T would be better. It would also be interesting to see the others handle his load(s) as well.
In my case I am supporting an SXVR-H16, and the SX CFW chocka full of filters, using the 2" F/T, same as Alex has, with no issues.
In respect of the motor/no motor, the F/T is a great setup. With the motor fitted you cannot focus manually (but then again, why would you?). two Allen head screws later and you have switched, I can do it in the dark) and the manual focus is all go. For imaging, the auto-focus using the motor is something to be experienced.
Gary

[spearo]

Hi
I have used both the JMI Event Horizon and recently the FT autofocuser on my C14.

To stop mirror flop I installed these:
http://www.optcorp.com/product.aspx?pid=8248&kw=flop&st=2
(simply perfect)

The new FT seems flawless to me, autofocussing without problem and carrying my new STL 11000m with 5filter wheel. So close to 4.5 or 5 pounds.

frank

[issdaol]

Hi Frank,

I am not getting mirror movement while slewing, it only seems to occur at fine focus so I am not sure what I am experiencing is mirror flop (or at least a bad case of it). However a mirror lock for a CPC1100 probably would not go astray. I have found the lock for the C14 but cant seem to locate one for the CPC1100 any pointers there??

All, thanks for the other comments, it looks like the JMI is out and it is now down to Moonlite or Feather Touch. Both look like sweet units.
The FT seems to offer more backfocus & drawtube travel options but I am a little concerned regarding Alex's comment.

Alex is yours a recent unit?? Or have there been further units/developments since then?

Cheers

[mithrandir]

I put a Moonlite on my C8 for almost exactly the same reasons. I rough focus with a Celestron Motofocus and fine focus with the Moolite.

The trick is to make the final focusing on the mirror turning the knob in a clockwise direction so the mirror is being pushed rather than pulled.

Then fine focus with the crayford.

It holds my DSLR or QHY8 without blinking an eyelid. The photos on Moonlite's site have it carrying a filter wheel and much bigger CCD than mine.

Also it can mount a focal reducer on the front of the drawtube so it is at a constant distance from the CCD.

[issdaol]

Hi All,

Thanks for the great comments & feedback.

At this stage is seems like the Moonlite may be the way to go and perhaps a replacement of the standard focuser knob with the feathertouch as well.

I will also be keeping and eye out for the mirror lock option as well.

Cheers

[AlexN]

Phil - Yep, Drawtube sag.. The drawtube is only extended 13mm of the possible ~65mm it can be exteneded, I've tightened up everything that can be tightened to no avail.. I can't seem to find where the movement is occurring.. I might contact FT and see if I can swap this one over, or at least check to see if its faulty...

My setup from the focuser back is OAG + QHY5 -> Televue 0.8x reducer -> Stainless steel 17.3mm extension -> 2" 7 position CFW fully loaded with filters - ST8300M ~~ All up about 3.3kgs. About 25cm in length.. Its a big load for a 2" focuser.

Essentially I'd like to have a 3" FT, but a 3" Focuser on an 80mm APO would be VERY hard to fit... I hate to say it but I fear my camera is too big for my scope! I could go back to a guide scope, lowering the weight, and the length of the setup.. But I do like the OAG.. makes life simple...

The FT is perhaps a month old.. so relatively new.

[Bassnut]

Not wanting to bury you in choices, but an electric FT is starting to look expensive and worrysome with Alexes experience. A 2" Optec TCS-F (http://www.optecinc.com/astronomy/tcf-s.htm) (takes 4.5 kg) and its 3 inch brother might be worth a look, and they have direct CPC1100 adaptor options. They also have a manual handbox for visual use. All the astro apps have drivers for them and some rate them "prefered choice" for accuracy, they are an industry standard. They also offer "absolute" positioning, Im not sure the FT does?.

[Louwai]

I have the F/T motorised + the primary micro on my C8. I started to set this up for photography, but then decided not to & so I only use it for visual.

Can't fault the F/T gear.
I have all 2" equipment. EPs, Diagonals, Powermate, etc. Have had no issue at all with weight, although I don't have more than the visual gear in it.

I also found the people at Starlight Instruments extremely helpful with postage & invoicing.

[AlexN]

MMM TCF-S is definitely the go.. Pricey.. but lets face it, every good focuser is expensive..

Just reading the associated literature with the TCF-S, Says it will securely hold and lift 10lbs... I'm sold - as soon as I can afford it... :(

[spearo]

Agree with Andrew regarding the focusing, needs to have the final focus turns pushing the mirror up and you shouldn't have any problem.

The beauty of the auto focuser is that it does that all by itself! very clever little piece of equipment
cheers
frank

[issdaol]

Hi Mate,

Any information is appreciated. I like to put in a lot of research before buying.

:eyepop:This unit looks like some very serious kit. I am not sure that the $2000.00 US price tag fits my budget for a focuser though :-(


Cheers

[AlexN]

The 2" TCF-Si is $645USD plus the cost of the adapter for your scope which is below $100US..

Its cheaper than a 2" FT with the FT digital focus system and the telescope adapter.. Although more expensive than the moonlite with stepper motor... The TCF-Si would be better than the moonlite I think, going on the specifications in the literature alone... Continious temperature compensation would be nice thats for sure.. although Fred tells me calibrating it can be a right pain in the butt...

[issdaol]

I might have to do a wider search then. The price list I looked at said over $1000.00 US for the 2 inch and $2000.00 US for the 3 inch.

Both the Moonlite and FT have native 3.25 inch attachment to the CPC1100 rear cell flange (although they do only have 2 inch draw tubes).

Where did you get your price from Alex?

[AlexN]

The Optec pricelist..

http://www.optecinc.com/astronomy/prices/astronomy_price_list.pdf

Page 7, Celestron 3" thread to Optec 2400 mount for TCF-S 2" focuser $63USD
Page 8, TCF-Si ~ 675USD

You would also need the cable to plug it into a PC, which is on that list, but I don't remember the page number...

The TCF-S comes with the external box for control purposes, the TCF-Si can only be used via PC connection, there is no manual control

Its still a pricey setup. The moonlite being much cheaper, and for most setups I would imagine it would be more than adequate.. Only reason I'm harping on about the TCF-S is that its the first focuser I've seen at a reasonable price that claims to be able to handle the weight of my camera with ease.

[Bassnut]

Yes, temp comp is not exactly a snitch, with any focuser, much set up and needs to be redone with any image train change, but works if your fussy. Ive loaded the TCF up with no bother, it works. Its the same old tale, its cool to have no drama autofocus that handles weight upgrades, but it costs.

If you intend imaging in the future, good autofocus (way more accurrate and faster than manually BTW) with focusmax is a welcome zero, invisible effort relief that makes good imaging slightly more achievable on a given night :P

[marki]

Have to agree. My moonlite has the stepper motor/moonlite controller option and setting up the temp compensation is a little challenging to say the least. Focus max in conjunction with Maxim works well on the autofocus routines but of late I just use the Bahtinov mask which is a real doodle (takes 2 seconds but you have to be there).

Mark

[tebling]

I'm following this thread now with great interest as I'm planning to upgrade the focuser on my Orion XT8i. It's a visual scope now, being on a Dob mount, but I plan to eventually buy a G11 and begin imaging with it.

If I were to purchase a F/T or Moonlite (still considering both options) and use it in a manual configuration can I later upgrade to the motorized option? I recall seeing something on one of the sites saying I'd have to send it back to the factory for the upgrade.

I have a slight bias at the moment toward the Moonlite because of the price and weight advantage (less moment arm on a GEM mounted Newt is a good thing from what I gather!)

And yes, I'm considering spending more on the focuser than the entire OTA! :screwy:???

[AlexN]

The moonlite can not be upgraded to a motorized unit after its been sent to you. You'd have to send it back and have them perform the the upgrade.. Also, once the moonlite is motorized, you can not use it manually from then on.

The FT you can upgrade to motorized at any time either by using the FT system or Robofocus.. It is a simple matter of undoing two Allen head bolts to remove the motorized unit and use the focuser manually if you so choose.. If the scope is going to be used as both a visual and an imaging instrument, I'd recommend the FT..

I think you would find that the FT weighs less than a moonlite... Thats my experience with them thus far... My moonlite was a proverbial brick in comparison to the FT.

[tebling]

Thanks for the info Alex! You're right, I had them mixed up with regard to weight. "Light as a feather (touch)!" :P

Since we only have one scope, I'd definitely like the option of being able to switch between visual and imaging. It sounds like the FT is the winner on that front.

[marki]

Definately agree with Alex there the moonlite focusers are big heavy units and will cause grief if you are on a fine balance. Not sure why you want to switch between manual and electronic focusing though. Once you use a good motorised focuser it would be very hard to return to a manual version as they will always cause the scope to shake. I find this really annoying when you are trying to achieve fine focus as the target keeps jumping all over the place and you have to keep stopping to let it settle down then check to see if it's right. This is not an issue when you have a motorised version simply press the button until the image is sharp and clean, no vibration ........

Mark

[tebling]

The only reason I was thinking that there would be a need to switch is when I want to travel with the scope to a dark site for visual only and not have to bother with supplying power to the focuser. Other than that one case, you're right - it should be of benefit for both imaging and visual.

[issdaol]

Hi All,

Thanks for all of the great advice and information.

I have been in direct contact with both Moonlite and Starlightinstruments.

Both companies have been extremely helpful providing a lot of information and assistance around their options.

Based on all of the information I have narrowed my choice to FT or Moonlite. At this stage the Moonlite is a little in-front of the FT until I review the information on the newer 3 Inch FT option.

Cheers