Focuser for Heavy Eyepiece

[ScotRod]

Hi All,

I've recently upgraded the eyepieces for my StellaLyra 10" Dob (which are amazing) but noticed that the focuser is struggling with their weight.  While I am able to adjust the two thumbscrews at the base of the focuser to hold the eyepiece in position, it quickly becomes a chore for finer adjustment as I need to loosen the thumb screws and physically "lift" the eyepiece up if I want to extend out.

I had a look around on other forums to see what suggestions there were and some suggested that there was an adjustment screw to tighten this up, but I'm guessing that this doesn't apply to this focuser due to the tension thumbscrews at the base.  I did check the other screws, but believe that there are not for focuser tension (unless anyone knows differently?).  I also saw a youtube video where the focuser was disassembled to file the edges of the focuser tube to improve the grip of the wheel, but I don't think that is going to help out in my scenario.

I'm guessing that for heavier eyepieces (in the range of 1KG) I'm looking at an upgrade.  That being the case, does anyone have a focuser recommendation for the heavier eyepiece?

Thanks!

[Jiggy 67]

I’ve had the same problem with my SW100 ED refractor which just can’t handle the weight of Morpheus ep’s and a Baader click lock Star diagonal, I have to sometimes push the focuser in manually. So I have a Baader Diamond Steel Track on order which can handle huge weights. I also upgraded my 200PDS to a Moonlite focuser but I don’t think they make them anymore for reflectors which is a shame because it’s a great focuser, maybe you can get your hands on a used one. 
Stock focusers just don’t seem to cut it unless you’re forking out thousands for a high end scope 

[Space Hopper]

Sourcing something that will do the job is going to be the main issue.

Moonlite, Feathertouch etc all have major supply chain issues, and in the case of Moonlite (perhaps the best Newtonian option) have no inventory at all and have stopped listing them completely.

Baader Planetarium may be an alternative.

A lot of the focusers you get with mass produced scopes are simply not designed to be used with big heavy 1kg + eyepieces.

And they often have insufficient range to focus at all with 2 inch eyepieces.

Here's the naff focuser supplied on one of my old OO scopes from years ago.

The drawtube extended internally and even fully racked out still wouldn't reach focus.

Unseating the Nagler 31 by about 10mm did the trick but the weight of it left the focuser drawtube with a noticable banana type curve. Not ideal.

An upgrade solved that, but if you can't source anything yourself i'm afraid you may be stuck for a time till supplies get moving again.

 

[Second Time Around]

Teleskop Express in Germany are showing 3x Baader Steeltracks for Newtonians in stock.

I use one for very long stacks with a night vision device and they support all this very well.

Edited April 24, 2022 by Second Time Around
Changed Service to Express

[johninderby]

The Baader Diamond Syeeltrack would be ideal and handles a 6kg load but will need new mounting holes but a simple job. Moonlite has discontinued their regular focusers and now only sell motorised ones. 

The CNC R&P focuser off the Bresserr dob would be ideal as it will handle a heavy load but expensive to buy on it’s own.

Edited April 24, 2022 by johninderby

[Space Hopper]

I like Baader stuff alot, but the Newt focuser has an issue or two in my opinion.

As well as being pricy, the base doesn't sit flush with the tube allowing dust and muck to get inside (and settle on your mirrors)

The drawtube only extends 40mm outwards which my not be enough for the OP to reach focus if he's using big 2" glass.

Moonlite was always a nice option with its perfectly designed curved base, and two included spacers to cater for pretty much all focusing requirements.

Such a pity they are no longer available.

[Second Time Around]

I agree that the base not sitting flush isn't perfect.  In practice though I haven't found it a problem.

However, the short extension to my mind is a plus rather than a minus.  A low profile design like this means that the secondary can be smaller for a given fully illuminated FOV, or the FOV wider for a given size secondary.

If you have a scope with the focal plane well outside the tube the simple answer is a detachable extension tube on the focuser.  I prefer such a location for the focal plane as this gives lots of flexibility for accessories.  On my OOUK Dobs the focal plane is 100mm outside the tube, and I find this ideal.

Apart from the heavy load that the Diamond Steeltrack accepts, the other feature I like is that, unlike the Moonlight, it has a scale to show the position of the drawtube.  I find this very useful when switching around accessories.

YMMV.

 

[Louis D]

There's also the GSO 2" Linear Bearing Crayford Focuser that might work for you.

The JMI EV-1n might work for your needs.  I have a similar single speed focuser from the 90s, and it works great under heavy loads.

Of course, there's always Feather Touch focusers, but they're on backorder.

If the focuser has a rack and pinion on it, you shouldn't have slip issues in my experience with a 2.5" focuser on my TS-Optics APO refractor.

[Clarkey]

8 hours ago, Space Hopper said:

base doesn't sit flush with the tube allowing dust and muck to get inside (and settle on your mirrors)

I put a steeltrack on my newt. To block the gap I used an oversized bit of sponge and screwed it down under the focuser. Once fitted I just cut of the excess. Works fine for imaging so it must be quite a good seal. I have two steeltracks and I have found them excellent.

[Second Time Around]

1 minute ago, Clarkey said:

I put a steeltrack on my newt. To block the gap I used an oversized bit of sponge and screwed it down under the focuser. Once fitted I just cut of the excess. Works fine for imaging so it must be quite a good seal. I have two steeltracks and I have found them excellent.

Excellent idea!

[Clarkey]

2 minutes ago, Second Time Around said:

Excellent idea!

Maybe I should suggest it to Baader. I think I even used the sponge from the focuser box!

[johninderby]

With all the various adaptors etc that Baader do surprising that they don’t do SW and GSO baseplates for the Steeltrack. 🤔

Edited April 24, 2022 by johninderby

[bomberbaz]

late to the party here but I use a moonlight on my 14" dob and have some seriously heavy glass to put in it.

However I didn't know they had ceased production. Don't know why as it is a sterling piece of equipment. 

[johninderby]

55 minutes ago, bomberbaz said:

late to the party here but I use a moonlight on my 14" dob and have some seriously heavy glass to put in it.

However I didn't know they had ceased production. Don't know why as it is a sterling piece of equipment. 

According to,Moonlight it was down to a shortage of materials so they decided to concentrate on the motorised focusers. 

[Louis D]

1 hour ago, bomberbaz said:

late to the party here but I use a moonlight on my 14" dob and have some seriously heavy glass to put in it.

However I didn't know they had ceased production. Don't know why as it is a sterling piece of equipment. 

It comes down to profitability.  The absolute profit on a $3000 motorized focuser is much larger than on a $400 manual focuser, so you concentrate on the former since the labor involved is similar for both.  GM and Ford have done the same with vehicles.  All US manufacturing is of high profitability full size pick-up trucks and SUVs.  Most of the smaller vehicles are made outside of the US to take advantage of lower labor costs.  Apparently, MoonLite didn't want to shift production out of the US to cut costs on manual focusers, so they stopped making them altogether.

[bomberbaz]

10 hours ago, Louis D said:

It comes down to profitability.  The absolute profit on a $3000 motorized focuser is much larger than on a $400 manual focuser, so you concentrate on the former since the labor involved is similar for both.  GM and Ford have done the same with vehicles.  All US manufacturing is of high profitability full size pick-up trucks and SUVs.  Most of the smaller vehicles are made outside of the US to take advantage of lower labor costs.  Apparently, MoonLite didn't want to shift production out of the US to cut costs on manual focusers, so they stopped making them altogether.

glad I got mine when I did, had it for around 5 years now and still going strong.