Decent focuser for Skywatcher 120ED?

[Mark_C]

Hi all,

I am currently using the standard Crayford focuser that ships with the Skywatcher Black Diamond ED120 and it has served its purpose well for visual use, however now that I am imaging I am starting to realise its limitations. I am experiencing terrible focus shift problems when moving the scope from one part of the sky to another, particularly when near the Zenith. I don't think it can handle the weight of the 0.85x reducer + Canon 60D very well.

I was wondering what people recommend as a decent replacement? Something that can handle the weight and stay put without any shifting. I was also considering an electronic based focuser too but they appear to be very expensive.

Mark.

[nightfisher]

The best is likely to be a feathertouch but lots of money, next might be a Baader steel track, also i think it might be revelation, has brought out a dual speed rack and pinion

[Thalestris24]

Focus lock?

[Zakalwe]

The standard Crayfords can e improved tremendously with a bit of tweaking.

I've used Steeltracks and Moonlites and they are both very good. The Moonlite is a lovely focuser though.

[Earl]

its a common issue, you can tweek them, but if your still getting slip, id look at a steeltrack first, Feathertouch ideally, dont forget you will need a push fit adapter for your reducer.

[rob0971]

I have a feather touch on mine & its brilliant, though very expensive. Would I buy another? If I could afford one yes. If not, the other upgraded focusers mentioned above will serve you well but won't be quite as good. Most are easy & cheap to motorise especially if you have some diy skills.

[Mark_C]

Thanks for all of your responses, they have been very helpful. I have managed to resolve the focus slipping issue by tweaking the tension plates that press against the focus tube, the focuser doesn't shift with the DSLR attached now which is good. One thing I have noticed is that the black micro focusing knob doesn't seem to work, in fact I don't think it ever has since I bought the OTA, could there be a reason for this? I spin it around but the tube does not move at all.

I am still tempted to get a better focuser anyhow, I don't feel the stock one is of a decent quality at all.

[ollypenrice]

A good focuser also needs to be convincingly orthogonal to the light path. If it isn't, it does not matter how good it is in itself. Pushing it into a tube and locking it with three radial screws, for instance, does not necessarily meet this requirement.

Olly

[YKSE]

There's a hole in that micro-focusing knob, inside the hole, there should be a screw which can be tightened. I found it when my micro-focusing stopped to work.

[swag72]

A good focuser also needs to be convincingly orthogonal to the light path. If it isn't, it does not matter how good it is in itself. Pushing it into a tube and locking it with three radial screws, for instance, does not necessarily meet this requirement.

Olly

Oh Olly speaks sense and I speak from bitter experience. I replaced the stock focuser on my ED120 with a Moonlite (Wouldn't go for one again incidentally) and Olly has hit the nail on the head. I could never get the thing properly square and orthogonal with the 3 screws holding the flange into the tube. Despite trying with a laser collimator and using all sorts to square it up, it never happened and the scope was sold to a guy who wanted it purely for visual. It was a big disappointment all round if I'm honest.

[Moonshane]

by the time you have bought a 120mm ED and a top of the range focuser. could you not just buy a Tak or similar?

[lensman57]

Hi all,

I am currently using the standard Crayford focuser that ships with the Skywatcher Black Diamond ED120 and it has served its purpose well for visual use, however now that I am imaging I am starting to realise its limitations. I am experiencing terrible focus shift problems when moving the scope from one part of the sky to another, particularly when near the Zenith. I don't think it can handle the weight of the 0.85x reducer + Canon 60D very well.

I was wondering what people recommend as a decent replacement? Something that can handle the weight and stay put without any shifting. I was also considering an electronic based focuser too but they appear to be very expensive.

Mark.

I have a Moonlight on my ED 80 and it works fine, or I just got lucky. Moonshane's idea is not bad but for the cost but if you sold the 120ED an Altair 115 Apo is not out of reach. Brilliant optics and a massive solid focuser.

A.G

[laser_jock99]

I had the same problem with my Equinox 120. The issue was the so called 'flat' contact part of the draw tube. You can dismantle this, hold a straight edge up to it and see that they are not flat at all. Instead of the Crayford roller friction contacting the whole width of the 'flat' draw tube part, it only touches the edges resulting in low grip and slippage under load. Fortunately the solution is simple- take a fine grade, flat (preferably new) honing stone and carefully hand hone the draw tube 'flat' flat. Check constantly the progress with your reference straight edge (engineers steel rule) in both directions (parallel & perpendicular to the tube) and in a few minutes you should have a much flatter contact surface. You will loose the nice glossy finish, but that coating seemingly is the cause of the problem!! Now my scope can hold a  DSLR looking at the zenith with no shift.  

No need to buy a Moonlight or Steeltrack- just fix the one you have!        

[Zakalwe]

I spent a bit of time adjusting the standard Crayford on my Equinox 80.  A tiny tweak on the screws is noticeable, but if you take your time you can make a massive difference. Once tweaked, mine held a focal reducer and DSLR no problem.

All standard Crayfords benefit from a bit of fettling TBH. The one on my Altair 115mm also needed a bit of fine tuning. I count it as getting to know the instrument.

[adamw]

Oh Olly speaks sense and I speak from bitter experience. I replaced the stock focuser on my ED120 with a Moonlite (Wouldn't go for one again incidentally) and Olly has hit the nail on the head. I could never get the thing properly square and orthogonal with the 3 screws holding the flange into the tube. Despite trying with a laser collimator and using all sorts to square it up, it never happened and the scope was sold to a guy who wanted it purely for visual. It was a big disappointment all round if I'm honest.

I agree with this. I bought a moonlite for my equinox 120ed and was surprised that when you loosened off the 3 screws the focuser body had at least 2mm lateral movement between the body and the adaptor flange. I did my best to line it all up using a laser colimator and the 3 screws. I am planning on having another go at it as i never checked it with the focuser rotated. A quality focuser though.

[recceranger]

Hi Mate,

I fitted a Baader Steeltrack to my ED80 and it's a great bit of kit but there were two issues

One was the extra £250 odd quid and the other was the fact that you then loose the ability to mount your finder scope. A bit of a loss considering the quality of the SW 9x50. If I were to do it again I would have stuck with the original focuser. Or I would have gone up market on the ED80 for one that had a solid focuser on purchase

[Earl]

yes finder bracket is a broblem, some do build one in as an optio iirc