I'm interested in the pro's and con's of these two brands of aftermarket focusers, particularly from an SCT perspective. I'm talking complete focuser unit for the the visual back (zero shift), not a fine focuser that would attach to the existing focuser shaft at the sides. Is a Feathertouch worth the extra money?
I've got a feathertouch crayford on my C11 (1.5" drawtube travel) - they're about $400 new including the adapter. It works very well, can easily cope with 2" diagonal and 41mm Panoptic/31mm Nagler, and the drawtube tension is easy to adjust and effective.
I've also got one on my Skywatcher 6" f/5 achro (2.5" DTT) - it has slightly more travel than the original focuser yet it protudes about 45mm less into the ota reducing vignetting, courtesy of a very short focuser body.
They're just very well designed and fairly light in weight and a pleasure to use in comparison with the SCT primary focuser.
EDIT: Mine are 2" focusers, I just realised you might be interested in larger diameter drawtubes.
I added a Feathertouch micro focuser 10:1 knob for my C9.25 OTA (around $140 from memory) then added a Meade motor focuser -> Shoestring Astronomy USB adapter -> PC for electronic focus control.
I love the Feathertouch it looks and works well; most noteably it unexpectedly improved mirror flop by a factor of 2x - 3x. When I used to reverse direction during focusing a star it hoped around fairly wildly in my field of view = Oh oh! After adding the feathertouch focuser the star shifting position during a change from inwards to outwards focusing (or vice-versa) went from horrible to neglible.
The Meade motorfocuser I use with a Bathinov mask to achieve the finest focus. I have found from experience a motorised fine focuser - even a low-end one - is a great thing to have.
So unless your OTA already has a focus lock on the primary - consider getting rid of the standard focuser that comes with your OTA (especially if its a Celestron)!
hi paul
ive a zero shift image focuser on the rear of my sct they are alittle noisy but with 4 speed control it works fantastically the image doesn't flop from side to side.also with a mirror lock you can get a rough focus then lock mirror and just use the electric focuser no image shift at all..
No contest, (apart from Ron's service). F/T for me sorry, I have two, to the one Moonlite.
If imaging is part of the long term plan it can only get better, again, the F/T digital system is stunning.
Gary
Just to clarify I'm looking at the VC200L which doesn't focus by moving the main mirror but by a R&P focuser at the visual back. I'm not very happy with its performance atm so that is what I'm considering replacing the standard focuser. I do have an orion motor focus unit that apparently fits so I'll likely use that in the interum.
The meade 8"SCT I have has a JMI zeroshift focuser attached which is fantastic for what it does especially when I control it from the PC with the Shoestring adapter. I wouldn't be without it for imaging. This is what I'm hoping to achieve with the VC eventually.
Atm I'll be looking to stick with the manual 10:1 focuser rather than the motorized one (been spending a bit too much lately with bad weather depression ) I know FT have one that is designed for the VC and I'm sure ML will have something similar, I'm just trying to gauge the difference in performance between the two. Just looking at the FT one makes me drool though. Gary do you notice any major performance differences between the two brands? And can both models be retrofitted with motors? And are the motors servo?
I have a feathertouch focuser on my TEC180. It is very good. No complaints really. Comparing it with Tak or AP focusers I would probably rate the 4 inch AP focuser as better as it is stronger and larger. But even then the AP one has a feathertouch microfocuser which is way better than the Tak add on one. But not as good as the new FSQ106 microfocuser.
TEC did some tests on its 3.5 inch custom feathertouch focuser. There is some minor flex at about 10lbs and the flex is less when the focuser is upside down. The AP focuser I doubt would flex if I put it under my car!
I use Robofocus on my focusers and I recommend them as very good pieces of equipment.
If it came to price I estimate a Moonlite + Robofocus would be far better than a feathertouch all by itself. The digital focuser is so much more precise and makes accurate focusing totally easy.
Perhaps a 2nd hand AP focuser with Robofocus if it would fit would be even better. AP probably can make an adapter quite cheaply if none exists.
Paul.
sorry mate, I have been a FT convert for ages, but digressed lately when I built the 12.5" truss, and found a decent price on a M/L unit.
But, it isn't built as well as the F/T, I am sure. Ron though is superb, THE best to work with.
Having had a VC200L or two though, the biggest snag is the filed correction lenses that Mr Vixen sneakily slipped into the draw-tube, you have that angle covered surely? I am sure any competent lathe worker could, it's just that I know you are not one of them, LOL.
Performance comparisons? I still believe the FT "feels" better, and am certain it will last longer. The Digital drive is great, expensive, but great. The Moonlite one is a fixture I believe, whereas the F/T is user removable, and at a later time.
Servo? Not sure, I use it with the H/C, but have also used it with the auto-focus routines in Maxim and also AstroArt.
Gary
Ok I've just been looking at the FT focuser that is recommended for the VC200 and I can't see for the life of me how it would attach. Unless it screws into the existing focuser draw tube. http://starlightinstruments.com/shop...roducts_id=226
The VC200L's r&p focuser is all one piece with the visual back and its collimating screws.
Any ideas??
atm just throwing ideas around. After buying the ap900 and getting the VC reground and re-coated it could be a while.
Well, since you asked.
If you can cosy up to one of the many competent machinists on this forum, toss the idea of a bit of DIY, to replace the Vixen R&P with the F/T unit, something like the FT2015 or maybe (if there is enough inside clearance) the FT2020. Where you will need the machinist is to machine a face-plate to accept the F/T and attach to the rear cell, with those collimation screws you mention.
But, always a gotcha of course, you will also need this machinist to fit the filed flattener lens system onto the front of the F/T draw-tube, at the correct distance.
Not rocket science, and given a decent lathe, and machinist, and a bit of drive it can and would be simple enough.
Of course you could just wimp out, and tweak slightly the bog standard unit, and fit it with something like a RoboFocus, others have and are quite happy.
Gary
Might have to go the last option in the end Gary. Not really keen on the idea of having to rebuild half the scope to fit a focuser. However when I looked at the site the FTF2515 (the link I posted) was the one for the VC200L. I just can't see how it was going to be fitted unless it screwed directly to the existing focus tube and the it was then locked down????
Might just try to fit the Orion electric focuser I have to the existing r&p and see how it goes Btw it does already have a 10:1 manual focuser attachment on it, just not happy with its action.
Can't hurt to try the simple option first, Robo.
The adaptor (just looked) seems to screw directly to the rear cell, and then accept their FT2.5" focuser, nice. Looks like the filed flattener lens cell screws to the front end, so similar to what I described above.
Gary
I have come to this thread late, but for my 2 bobs worth, I have used both a Moonlite focuser and a Feathertouch focuser on my 20"SDM, and I prefer the Feathertouch.
Both are beautiful, so you can't go wrong, however, for mine, there is a perceptible difference.
The Moonlite has a heavier, more solid feel. It is probably more beautiful to look at. However, over time mine showed considerable wear and tear in the shaft, to the extent that there were intendations that caused the feel to become increasingly clunky and stiff. It may be reflective of a very intense period of observing over several years, and also perhaps it may have received a bump when I flew over a road bump through Binnaway on the way to Coonabarabran for an observing week!
The Feathertouch is buttery smooth, and shows no sign of any wear or tear at the moment. Sometimes I find the fit tight when putting in two inch EPs, but with a bit of a wiggle, there is not a problem. I find it very easy to snap into focus, perhaps a little more distinctly than with the Moonlite. The Feathertouch has two tightening screws for more secure grip of the EP compared with only one screw for the Moonlite.
When I had the Moonlite, I loved it. Everyone else I know has also loved theirs. It is line ball, and probably some of my experiences may not be replicated by others, so you would not be going wrong with a Moonlite if that was your choice.
I think the config you need yours for is different from mine, so there may be other issues as play that I am not aware of.
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) I know FT have one that is designed for the VC and I'm sure ML will have something similar, I'm just trying to gauge the difference in performance between the two. Just looking at the FT one makes me drool though. Gary do you notice any major performance differences between the two brands? And can both models be retrofitted with motors? And are the motors servo?
