Wanted - A focuser

Cypher_parts · #1 06-01-2006, 02:45 PM

Anyone out there with a decient Crayford focuser they want to sell ?
Looking for something to fit my 8inch F5 Saxon Reflector, the fine focus on the moonlite SC2 seems to be a good idea, so if anyone is upgrading and has a suitable high quality crayford and wants to sell it , I would love to hear from you .
Thanks ..

iceman (Mike) · #2 06-01-2006, 02:48 PM

Have you tried the GS crayfords? They're only $99 and are a huge improvement over the standard R&P focusers.

I'm not sure what mounting plate you'd need for a saxon OTA as opposed to a GS OTA, but someone out there will know.

Cypher_parts · #3 06-01-2006, 05:21 PM

where abouts do you get one of these $99 GS crayfords ? im in Knoxfield Victoria AU , Is there somewhere local that I can purchase this or does it need to be ordered ?
thanks

Astroman (Andrew Wall) · #4 06-01-2006, 05:27 PM

try Bintel or Andrews communications

www.bintelshop.com.au
www.andrewscom.com.au

janoskiss (Steve H) · #5 06-01-2006, 05:46 PM

Bintel, Melbourne.
519 BURKE ROAD CAMBERWELL VIC 3124. Phone: (03) 9822 0033

iceman (Mike) · #6 06-01-2006, 07:43 PM

Speak to Roger Davis at the Bintel Melbourne store, he'll know what you'll need to mount it to your OTA.

Cypher_parts · #7 09-01-2006, 07:53 PM

I got a gs crayford this arvo from Bintel for $99, nice people up there and a whole lot of things to druel over .

So now im back at the workshop fitting it and finding a few new problems.

The GS focuser while it has the exact same hole spacing as my old R&P focuser the base holes are drilled streight on the GS focuser, not on an a slight angle thus the nuts dont sit flush on the inside of the telescope, and thus also previously used screws were not long enough, no screws with the new focuser so I had to hunt around for some screws , and a hour latter fitted the new focuser .

All mounted now...
The alignment looks pritty good, so outside for a quick test,

ok new problem .. tring a 20mm eyepiece the basic one that came with the reflector when i bought it, I tried focus on some trees that are a few blocks away, seems the focal length is short now by about an inch.. so any hint on what to do about this ?

Next problem the screw that tightens the 2' eyepiece on the new GS focuser is stripped ...( gees that lasted long ) on closer inspection seems that its not even the right thread, while I can probabaly find a thumb scew with the right size thread or retap it, finding that its stripped and wont tighten after going to the trouble to mount it is a bit of a buggar.

I an additional inch longer in the focal length to focus ....arrrrrkkkk cant anything be simple ?

I dont know seem like maybe this reflector is just all wrong , maybe it needs a longer tube so as to have a shorter focuser ??

most frustrating .. I need some more advise ..

thanks guys ...

matt · #8 09-01-2006, 08:24 PM

You could speak to them about a spacer or 1 inch extension tube?

I had a similar problem when I bought a gs crayford from Andrews. Measure the racked down and racked up height of your original R&P and work from there.

You'll need to make sure your new focuser had similar racked up and down height/s.

make sure you measure from the top of the eyepiece holder without an EP inserted.

Sounds like a 1" spacer/ext tube will fix it though

rochler · #9 09-01-2006, 08:28 PM

Hmmm... I just went thru this a while ago! What you need to do depends on exactly what the difference is between the old focuser & the new one.

What you should do is measure the distance between the outside of the OTA and the base of the drawtube when it is fully racked in (old focuser), and then rack it out and measure the distance again (old focuser). That will tell you height of the drawtube from the OTA (i.e. the profile of the old focuser) + how far it racks out (i.e. the drawtube length of the old focuser).

Repeat with the new focuser, so you can determine what the difference is. This should tell you whether you have problems with in-travel or out-travel (i.e. whether you need to get a spacer inserted between the crayford & the OTA, or whether you need to get a drawtube extension). Does that make sense? You shouldn't need to refit the old focuser to measure this, it should be straightforward.

Since your old focuser focussed o.k. then the problem can only be either that the new focuser has a lower profile, which is causing you problems in racking in far enough to reach the focal point for your EP, or if the profile is the o.k., then it must be that the drawtube can't travel out far enough. Either way, you should be able to get either an adapter/spacer for the focuser so it sits up higher, and/or an extension tube.

What you are trying to achieve is to get a very close match to the old focuser in terms of profile and drawtube length.

Of course, that may present problems with finding longer suitable socket head cap screws to fit. You may need to source from a wholesaler like 'Coventry Fasteners' - they do up to 50mm in M3, M4 & M5 (stainless, zinc or HT).

PM me if you need any clarification....

matt · #10 09-01-2006, 08:50 PM

Yep, and check the length of drawtube travel, like rochler says.

Your newt is almost identical to mine, so i'd make sure of at least 1.5" of travel, if not 2 to be on the safe side.

I ended up changing to a Moonlite CR2 for a variety of reasons.

A lot more $... but a lot more happy

Cypher_parts · #11 09-01-2006, 09:35 PM

well if i put my Camera t-piece adaptor in, which adds about an inch focal length, and then pop the 20mm eyepeice in it, *walla* I can get focus just at the end of the travel on the new gs crayford, not ideal but usable .

Travel length is actualy a little better on the crayford that my old R&P by about 10mm but the difference is in the 1.25' eyepeice holder the old one measures nearly 45mm high and the new one on the crayford is only 15mm so i need a spacer of about 30mm or a little over an inch, to set it all right , question then is what happens when i fit a 2" eye piece will it have focal issues too ?

where do i get an extention tube and idea on price ?

thanks all for your comments they are all most interesting

Cypher_parts · #12 09-01-2006, 09:59 PM

Quote:

Originally Posted by matt

Yep, and check the length of drawtube travel, like rochler says.

Your newt is almost identical to mine, so i'd make sure of at least 1.5" of travel, if not 2 to be on the safe side.

I ended up changing to a Moonlite CR2 for a variety of reasons.

A lot more $... but a lot more happy

Overall ... I am very happy with the difference in this focuser in comparison to the last one its ten thousand times better , now bring on some clear skys

How do you know mine is almost identical to yours ?

Just to clarify I have a Saxon F5 1000x200 8' reflector thing on an eq6 mount with a motor drive, now with a GS crayford ( which looks realy nice )

I was going to get a CR2 they seem to be a good way to go but no one has offered me one cheap

.
The other issue there with the moonlite CR2 they are even smaller so thus the problem would be bigger , and from the pics of the C shape construction they look like they would alow dust into the tube when not in use ?

janoskiss (Steve H) · #13 10-01-2006, 12:36 AM

Tell to Bintel about the problems, especially about the stripped/misfit screw. Most of us buy from Bintel because of their reputation for excellent service. Might as well make the most of it.

matt · #14 10-01-2006, 04:19 AM

My Skywactcher OTA is an 8" f5 (200mm x 1000mm fl) just like your Saxon. They're fairly common scopes.

I know coz I know

iceman (Mike) · #15 10-01-2006, 05:48 AM

When I got my moonlite CR2, I ordered the 1" spacer to ensure the focus travel was the same with the old R&P as with the moonlite.

I got my mounting kit and spacers from DBA astronomy in the US, for only like $15US.

matt · #16 10-01-2006, 05:56 AM

Exactly Mike

Like I said in the earlier post ... the additional 1 inch spacer should do the trick

Ron at MoonLite has all the specs and is great. He'll see you right.