Protecting Eyepieces in none compression focusers

[Optical Dob]

Hello, I would like to get a better eyepiece but have a standard focuser without the compression ring. Do any of you have any little tricks or ideas on how I could stop the screws  scratching the barrel, or am I over reacting. Would tape of some sort work? 

Thanks.

[Stargazer_00]

replace the extensions with ones with compression rings they cost less than 20 pounds. check altair astro under photo visual adapters.

[emadmoussa]

I really don't even remember what non-compression focusers were like.. But yeah, I could imagine them being a complete pain. I believe there are solutions to this problem, if you google compression focuser replacement?

[BillP]

The least expensive option is to go to a hardware store and get the set screws with the same threading in nylon instead of metal.  They work just as well at securing the eyepiece and will not scratch the metal of course.

Example - http://www.shop4fasteners.co.uk/acatalog/shop4fasteners_hexagon_setscrews_nylon.jpg

[Moonshane]

what Bill said.

[emadmoussa]

What Moonshane said Bill said...

[Moonshane]

LOL

[Pig]

What Imad said

[Scott]

What pi..... oh forget it.... Must say it's a good idea though. can't say i've thought of it although my ep's aren't really what you'd call top end

[Stargazer_00]

I still think my suggestion was the right one :/

I wouldn't chance any of my eyepieces to a nylon screw which could snap off if overtightened.  Also it won't seat the eyepiece in the centre like a compression ring will (do a better job of doing).  I also read the OP as a way to fix eyepieces for visual use, not put the eyepieces right into the focuser itself which is why I spoke about the extensions.  I assume everyone uses a extension, right?  I've never had any eyepiece come to focus directly in the focuser itself.  I've just left those screws as they were delivered. The extensions I've put in don't come out at all so I dont mind so much that they are held in place with screws.

the compression ring extensions are cheap as chips and work perfectly although they are 2" extensions so you'll need a 2" to 1.25" apdator too with a low profile.  They sell these on Altair Astro too, self centering ones, and they are also less than £20 I think.

[Optical Dob]

Thanks everyone for all your suggestions, I'll have a good look into all of them. Yes Graham it will be for visual use and i will have a look at those adaptors.

What Moonshane said Bill said...

Neil.

[bingevader]

Or would one of these do? It's what I use, but out of stock atm.

They also do very low profile adapters if you were looking to semi permanently fix it to your EP, sorry out of stock too!

Cheers

[Moonshane]

the chances of an eyepiece falling out of a dob even if in a focuser without anything holding it in other than gravity are pretty remote. you only need a whisker of tightness with a nylon bolt to hold it in, not a 'dying strain with a grunt'.

all that said I did buy dual speed focusers for mine which I really like and they have compression fittings. be aware that the brass clamps in them can mark the barrels too and in some cases, snag on the undercut on most barrels resulting sometimes in a dropped eyepiece - not happened to me thankfully but has to others.

my view on scopes and eyepieces is, yes, look after them but they are meant to be and should be used out in the field (or garden) where it's often dusty, grimy, damp etc etc and they will no doubt show some signs of wear over a period of years. if they don't then get out more

[swamp thing]

 I assume everyone uses a extension, right?  I've never had any eyepiece come to focus directly in the focuser itself. .

I must be the odd one out then. Never use an extension piece in my 10" Dob.

Never needed one in any of my old scopes either.

Only my 12mm Nagler needs one when its in my larger scope, this is the only time I ever need to use one.

[faulksy]

365 astronomy sell steel thumb screws with a nylon tip around 2 quid each

[BillP]

I must be the odd one out then. Never use an extension piece in my 10" Dob.

Never needed one in any of my old scopes either.

Only my 12mm Nagler needs one when its in my larger scope, this is the only time I ever need to use one.

I've never used an extension either.  Only eyepiece I've had that needed one was a Siebert Observatory 36mm.  For that one could not let it sit in the focuser to the shoulder but had to lock it in at the very edge of the eyepiece's barrel.  Other than that one eyepiece, everything else I've had comes to focus fine in my Orion USA Dob (XT10).  I usually hear people not having enough in-travel to come to focus with a Dob rather than out-travel.

[Stargazer_00]

Maybe its a skywatcher thing only then?  All my scopes have been Synta brand scopes.  They all require at least 35mm extension (newts) and my 14" doesn't focus with less than 50mm extension.

[Moonshane]

it's the same with OOUK scopes. all mine need a 50mm extension to focus. it's likey to be a compromise to keep the tube as short as possible, to have the focuser a few inches more down the tube for dew prevention or to make the trusses shorter and therefore the structure less flexible.

[swamp thing]

I think it's a camera thing Shane. In the old days one would move the primary up the tube to a second position for photography.

[Moonshane]

good point Steve.