Help with 2" Diagonal for Celestron OMNI XLT 120

[Photonmonkey]

I have recently purchased a Revelation 2" Dielectric diagonal for use with my XLT 120, however as there is no compression ring fitting in the standard 2" focuser on my scope I bought a 50mm extension tube with compression ring fittings.

The problem is with the extension tube and 2" diagonal fitted I dont seem to have the travel to focus my EP's :0(

I dont want to use the Revelation Diagonal without compression fittings as I know I would damage the nicely machined nose on it, any ideas for another way to get compression ring fittings on my focuser!!

I know i can unscrew the end of the stock focuser but not sure if there is anything I can replace it with?

Gutted at the moment as really keen to try out the new diagonal and my new Hyperion EP :0(

Thanks

[Moonshane]

hi there

I think (hope) I suggested ordering the diagonal first and checking the travel but anyway, there's another possibly way around this and that's to look at this thread

http://stargazerslounge.com/equipment-help/130402-compression-ring-part.html

maybe the seller of the extension tube will accept the tube back (or exchange it for something).

I am sure you'll get it sorted. Even if you have to keep the extension tube (unlikely) they come in useful and you'll use it in the future.

Good luck.

Shane

[Photonmonkey]

Hi Shane, you definately advised to check the travel! In my total impatience to get going i just ordered the extension tube without checking (foolish mistake on my part!)

Not concerned about having the extension tube as may come in handy anyway and did not cost the earth, your advice was sound just my lack of reasoning that let me down :0)

Just not sure what to do now, cannot believe these things are so hard to come by!!

[spaceboy]

I use nylon thumb screws which work fine. Email this guy, he should be able to get you some if you decide to go down this route. Skywatcher 120 ED DS PRO Refractor Telescope APO | eBay UK

[Moonshane]

Hi Shane, you definately advised to check the travel! In my total impatience to get going i just ordered the extension tube without checking (foolish mistake on my part!)

Not concerned about having the extension tube as may come in handy anyway and did not cost the earth, your advice was sound just my lack of reasoning that let me down :0)

Just not sure what to do now, cannot believe these things are so hard to come by!!

thank goodness for that. I am sure you'll use a 2" extension in the future at some point anyway.

that link I mention above does work well but you'd have to wait a bit. Nick's idea of nylon thumbs is not bad. I'm a scardeycat though.

[Moonshane]

with the 2" extension in place how far away are you? (or another way, with the 2" extension out, how much out travel do you have left?).

[John]

The 2" diagonals swallow up quite a lot of inward focus travel compared to the 1.25" ones. With all my refractors I've had around 25mm of travel left when at focus with Tele Vue Naglers and Plossls, a fair bit less than this with orthos which themselves need a bit more inward travel.

I've given up worrying about marking the barrels of diagonals now - I more concerned that my Ethe / Naglers have a solid seat to sit in !.

[Photonmonkey]

Shane, I think I am only a few mm out, between the cloud last night I tried to focus on the moon with my 25mm EP, moon was just out of focus when the tube was racked right in!!! Really frustrating :0(

Dilemma is now do I try and get the adapter in your link from the States which might take a while and cost a fair bit or get some nylon set screws as recommended by Spaceboy, again something I had not thought of!!!!

All I know is I want to get out there and observe with my new kit but know I will wreck my Diagonal with those nasty set screws on the stock focuser, really impatient now :0(

Still I am deeply greatful for all of your advice and loving the forum ;0)

[Doley68]

Hi.

I'm the one who had exactly the same problem as you & decided to get the part from Scopestuff in the USA. It worked out quite expensive but it's a well made part and has the added advantage of centering the diagonal as well as not scratching it to bits. I'm chuffed with it....just a shame you have to shop 4000 miles away to get it. What ever happened to great British engineering eh.

By the way, I hit focus about 20mm racked out with my 2'' WO dialectric.

[Photonmonkey]

Just out of interest what would the screw end of my focuser tube be called is it a male T2 thread or is this wrong as have seen some 2" adapters with compression rings advertised by Teleskop Service which I believe is a German company, just thought it might be quicker to order from a German Company than one in the States?

[Moonshane]

if you are talking about e.g. Adaptor from T2 thread to 2' female

this is might just work.

I'd email them and see what they say. I think though that personally, if you bought a dual speed crayford (e.g. at £120) then this would save £40 for the clamp so £80 and you could sell your focuser for maybe £25 so for a net overall cost of about £55 you'd get a much better focuser. Just a thought - used would be even better of course.

[Photonmonkey]

Hi Shane,

yes that was the one, as if I removed my nasty thumb screw bit at the end (not even sure what its called) I think the length of the adapter would be ok.

I was looking at the dual speed Crayford at £120, would this be simple to fit on the scope and is it worth doing for the OMNI XLT 120?

Thanks

[Moonshane]

I fitted the same one to that scope and if you are likely to keep the scope for a year or two, it's a lovely addition. It makes focusing so much smoother and it's really well made. It was an easy fit once I sanded off a little excess paint on the inside of the tube where it fits on. No cutting or drilling etc. You could even sell (or return?) your extension to part fund it. I sold my original focuser very quickly at about £28 delivered but you could retain it and refit if you ever sold the scope and wanted to keep the focuser for another scope.

I never regretted it for one minute.

[Moonshane]

here's a link to my scope when I sold it. http://stargazerslounge.com/completed/112599-sale-celestron-omni-xlt-120mm-f8-3-achromatic-refractor.html

I cannot find the one where I changed over but it must be somewhere.

you can see how good it looks anyway.

[Photonmonkey]

I am nearly sold on this idea now Shane ;0) was it the Skywatcher one?

If it is literally unscrew the old and on with the new at least it would save lots of hit and miss trying compression ring adaptors!!

[Moonshane]

if you can afford it then it's definitely a big improvement. yes, I used the SW one and it's literally take off three screws, pull off the old focusers (this was a little tight but came off quite readily) and then put back in the same hole and use the same three screws.

As mentioned I had to sand/scrape off a little excess paint on the inside of the ring where the focuser fits on but this is hidden once the focuser is in position. It's just a straight replacement.

[Moonshane]

ps

the focuser is really well built and very smooth and wobble free. the fine focus is superb for the money. it's all adjustable too so don't panic if it arrives and the drawtube slides in/out easily.

I bought new but they seem to come up every now and again used but not often.

[Photonmonkey]

I think this may be the way to go, I will put my SWAN 33mm on hold and go for the new focuser, at least then I will be able to safely enjoy my new diagonal and Hyperion!

I appreciate the advice from someone who has had first hand experience with this scope. When all said and done I do really like the XLT 120 and will probably keep it for a good while :0)

[Moonshane]

as you say, the focuser will benefit all your observing and eyepieces.

just keep an eye out for a used SWAN (I will PM you some details of someone that might actually BE selling a used one).

good luck and feel free to ask any questions when the focuser comes.

cheers

Shane

[Photonmonkey]

Great stuff!

Thanks Shane

[Doley68]

Hi. The draw tube thread is M52 I think so the adaptor wont fit. New focusser best idea of course, just a little pricey for me.

Good luck with whatever you decide.

[Rossco72]

TS do an adapter which screws onto the end of the focuser and provides a 2" twistlock fitting but it costs a few quid.

[Photonmonkey]

Thanks all for your great suggestions, think I will go for the new focuser, however, Shane does it have a mounting for the finder as noticed this is attached to the current focuser and could not see a mounting in any pictures on the web of the SW Crayford?

Cheers

[spaceboy]

As far as I'm aware they don't. You will have to get a shoe and affix it to the focuser. The shoes are around £7 from most astro shops.

[m.tweedy]

would this work

2" Self Centering Adapter Orion USA :: Adapters - Photo Visual :: Altair Astro