time for a new focuser

[Steve Ward]

Another thumbs-up for the Revelation focusers from me .

Just fitted the SCT version to the new Mak180Pro and I'm extremely happy with it.

I've fitted the SW 'autofocuser' to mine for USB control with the 'Homebrew' system , no great hassles to fit but I had to make a custom bracket first.

It was made from a 40mm length of 100 x 65 aluminium box section split in two in order to get a good corner , the fixing hole positions for the actual motor body are too close to the edge to use a piece of flat bent to shape , the radius can't be make tight enough to allow drilling accurately.

A very worthwhile exercise that gives extraordinary levels of focus control for a very good price.

[memoryman]

Hi Paul.

I'll try to answer as fully as I can...

1) There is no tube slop. None. Zip. Nada. The compression ring has a single thumb-knob which holds the 2" adapter or eyepiece in position. From fully open (slack) to holding firmly takes about a 6th of a rotation of the knob. Once at that level of grip it is very firm and nothing moves. Please note, I only have experience of the SCT version and am not sure if it's the Newt version you would need? I'm sure the tolerances etc are the same across the range though. Tolerance figures? No idea but I know when something's right!

2) I cannot imagine it would be "Dead Centre" simply becaue it has only a single thumb knob, which will only apply pressure from one side of the compression ring. However, see answer 1 above. The diffrence between the knob being "slack" and "tightened" (holding eyepiece or diagonal in place for example) is very very small amount. I would say that certainly for visual the centering would be fine, but for a high precision laser collimator? Personally I'd go with it, but I'm not going to say "exactly" centred.

Please note, that with my two inch barrel eyepieces, to slide them into the focuser directly they are actually pushin against the inner edge of the drawtube, such is the lack of space for movement in there! My diagonal on the other hand has a ever so slightly less tight fit. I'm going to replace the nosepiece of the diagonal with one that doesn't have a safety cut too as that does interfere with the compression ring holding position.

3) No it's not an issue when used with SCT or Mak scopes. The main focus is done with the telescopes own native focus control. Then, when in a "near focus" position the mirror is locked (if the scope has that function) and then the Revelation focuser is used to fine-tune. The coarse and fine focus knobs have plenty of sensitivity and there's plenty of room in that scenario to achieve great focus. If you were switching from say a 31mm Nagler to a 4mm Ortho, you may then need to adjust the main focus using the scope's own focuser first, but for my own eyepieces I've not had any problems at all.

For use with a SN scope though, I suspect the situation may be different as the Revelation will be the only focus mechanism on the scope. Yes, you may well need spacers or extension tubes, but until you try it you probably won't know. Although, what you could do it set your scope up and focus on a star using every single eyepiece you own and measure the position of focus on your current focuser. That will give you the distance from the secondary mirror where focus is achieved. You could then get the measurements of the new focuser (body depth, drawtube travel, etc) and work out if the focus positions would be achievable with the new focuser in situ without extensions. If needed they can be bought cheaply enough.

I'm using it with Intes M603 and Orion US 180mm Maksutovs. The scopes own focus knobs are plenty usable on both scopes, but both do not have the sensitivity required for critical high power focus adjustment with zero mirror slop. The mirror slop is completyely removed when using the add-on Revelation focuser (or for that matter any other add-on focuser that's well-engineered) and so you can focus totally on achieving best focus rather than worrying about where ther target is going to wander off to!

4) When sticking it on a SCT or Mak it just screws onto the rear port. Simples. Some Maks may need an adapter ring to provide the correct thread, but that's it. Nothing further required. If your scope's collimated already the new focuser shouldn't affect it. again, for a SN scope it may be different. I'd imagine it would be simple enough to centre the focuser drawtube hole over the secondary, just as if you were collimating. I'd imagine that little if any adjustment would be needed though.

Hope this helps,

Ant

Thanks for the advice.

Re: Centering.

Revelation make a self centering 2"-1.25" eyepiece adaptor and I wondered if it was worthwhile buying one? Presumably, as they make it, this adaptor will fit their new focuser?

Is the Revelation Superfocuser flocked and baffled (the Baader Steel Track Crayford focuser drawtube is)?

There is an amateur Astronomy Show in mid May, so hopefully I'll be able to look at one in close up!

P.S. Do you know Revelations contact details?

Paul

[A McEwan]

Re: Centering.

Revelation make a self centering 2"-1.25" eyepiece adaptor and I wondered if it was worthwhile buying one? Presumably, as they make it, this adaptor will fit their new focuser?

Is the Revelation Superfocuser flocked and baffled (the Baader Steel Track Crayford focuser drawtube is)?

There is an amateur Astronomy Show in mid May, so hopefully I'll be able to look at one in close up!

P.S. Do you know Revelations contact details?

Paul

The drawtube is matt-black inside with a multitude of fine ridges.

Wothwhile getting a self-centering adapter? As in my previous post, I wouldn't bother. Worthwhile for you? Only you can tell!

As far as contacting Revelation I've only ever asked Telescope House about their products that they sell. No other info I'm afraid.

Good hunting,

Ant

[memoryman]

The drawtube is matt-black inside with a multitude of fine ridges.

Wothwhile getting a self-centering adapter? As in my previous post, I wouldn't bother. Worthwhile for you? Only you can tell!

As far as contacting Revelation I've only ever asked Telescope House about their products that they sell. No other info I'm afraid.

Good hunting,

Ant

Thanks.

I presume that the internal ridges are threads for filters and act like baffles?

I've just found out about the Howie Glatter Parallizer and the concept of keeping the eyepiece parallel to the optical light path and the drawtube looks interesting.

It's listed as a 2" to 1.25" adaptor. Doesn't that imply that there isn't an equivalent (or a standard draw tube), that holds 2" eyepieces/laser collimators/autocollimators parallel to the optical light path using the same concept?

Or am I missing something?

[knobby]

Agreed. It does feel lovely to focus with. i found that i had to adjust all the elements of the focuser to get it feeling just as i wanted it. Once done, its grand! I would recommend them - very well put together. Certainly eliminates mirror flop!!!

Ian

Hi Ian, when you say adjust all elements. ..where did you find the info as to what to adjust?

Thanks

[memoryman]

It's been a long time, but eventually I bought a Revelation Astro Crayford 10:1 focuser off an astro friend 2mths ago that he bought at Astrofest, but had never used. I bought it for £60, which isn't bad as they retail for over £115 new! I also bought a Takahashi 3" extension tube off him for £20! Result!

It handles my 17mm T4 Nagler without a problem and even the 1 kilo 28mm Nirvana I bought used on Saturday! Another result!

[Tinker1947]

You may want to get a electric drive unit some time in the future, the Steeltrack has one, when i inquired about a Moonlight the info given said it need to be factory fitted and needed to be used all the time, something you might want to check on with what ever unit you decided to buy...

[KyleStoke]

Hi i was also looking to upgrade my focuser on the SW 80ED, is this http://www.harrisontelescopes.co.uk/acatalog/Revelation-Superfocus-2-inch-SCT-Rack---Pinion-Focuser--.html

the same one but for £100 less?

dose anyone know if it is easy to replace the standard focuser for ether this one or the correct one, if this isn't the correct one?

[A McEwan]

Hi i was also looking to upgrade my focuser on the SW 80ED, is this http://www.harrisont...-Focuser--.html

the same one but for £100 less?

dose anyone know if it is easy to replace the standard focuser for ether this one or the correct one, if this isn't the correct one?

Not quite. That's for an SCT telescope. Ant

[dyfed0_0]

On ‎13‎/‎12‎/‎2012 at 23:00, A McEwan said:

Well my Revelation Superfocus SCT focuser arrived today - and I'm impressed! Attached it to the Orion 180 and took some quick snaps of it.

The "coarse" focus is nice and smooth, but weighty too. The fine-focus is just as smooth, if not more so, but with a lighter feel. Everything feels "true" and properly aligned so far.

Build quality is very nice and it's quite hefty too. All the components appear blemish-free, and the brass rack looks very stylish as well as being functional. The lock knob is a big chunky affair hidden underneath the body of the focuser. It has quite a range of travel, with only the very last little bit of it having the desired "lock" effect. Nevertheless, it is effective.

Very shiny, looks great. Haven't tried it on the M603 yet. No chance of first light - it's snowing!

Quick snaps to show it off a bit. Oh, and it IS rotatable, though the blurb on TH's website doesn't mention that fact.

Ant

Hi there,

I have a Celestron Nexstar 6SE and I am looking for a focuser that I can use to fins tune. I have come across a Revelation SCT Focuser but this part I hate, working out the thread adapter I need to get for something, This time I aam going to ask. The Knurled Brass adapter attaching the focuser to the visual back, may I ask what type of adapter is it?

The Current visual back is I have is the standard SCT to 1.25" Visual Back.

Sorry for bothering you.

Kind regards

[RayD]

16 minutes ago, dyfed0_0 said:

Hi there,

I have a Celestron Nexstar 6SE and I am looking for a focuser that I can use to fins tune. I have come across a Revelation SCT Focuser but this part I hate, working out the thread adapter I need to get for something, This time I aam going to ask. The Knurled Brass adapter attaching the focuser to the visual back, may I ask what type of adapter is it?

The Current visual back is I have is the standard SCT to 1.25" Visual Back.

Sorry for bothering you.

Kind regards

You shouldn't need any adaptor for the 6SE as it is already a SCT thread.  As long as your focuser is SCT, then it should screw straight on 

[dyfed0_0]

On ‎08‎/‎07‎/‎2017 at 09:08, RayD said:

You shouldn't need any adaptor for the 6SE as it is already a SCT thread.  As long as your focuser is SCT, then it should screw straight on 

Great, thank you..... Always found these things Hit or miss so I am really grateful for your response!!

[Dave In Vermont]

That focuser looks to be a hybrid of the GSO's made for SCT's, and someone elses focus-knobs and parts - like the brass pieces. Looks very good indeed! It should be a vast improvement from the stock focuser. I did similar to my 12" Meade LX90. Now I find the mid-range of the stock-focuser and leave it there. Then do the fine-tuning of my focus with the Crayford 10:1 SCT focuser (mine is purely a GSO).

With this all signs of mirror-flop are gone. You should be very pleased with your upgrade!

Dave