GSO 1.25" Crayford Focuser for Reflectors - Single Speed

[Dave In Vermont]

I had neglected to address the one issue that I had with my GSO 200mm F/4 Rich-Field Newtonian Reflector, which I bought in 2002 or 3. This was the focuser on it.

As the scope was made before two-inch focusers were the normal standard, mine had a 1.25" R & P single-speed one. After I had taken it apart and greased it with some super-duper Teflon®-based bicycle-grease, it was certainly smooth enough to prevent any major impediments to using it. But a Crayford-Focuser was always in the back of my mind and to-do listings. And I had looked high & low & sober <even> for a likely replacement. One that didn't require major-surgery to the OTA itself. And such was non-existant in my neck-o-the-Universe. Until very recently.....

While looking into Crayford-Focusers for my other telescopes (see signature), I saw a new entry on a listing out of AgenaAstro in California: A "GSO 1.25" Crayford Focuser (with 176mm base plate) for Reflectors - Single Speed." And went straight to the listing:

http://agenaastro.com/gso-1-25-reflector-crayford-focuser-single-speed.html

And at $85.00 US (£59.02), the price wasn't trying to murder me. So I listened to the lovely Sirens' song and 'pulled-the-trigger.'

3-days later, it landed. Well-boxed (double-boxed, as Agena always is good about doing). Flipped-open my Bali-Song and in a moment it was on my desk. Perfect condition. After figuring out the tension and release bolts, I dropped it into place where the old R & P one had lived for 14+ years. As the listing on it from Agena had given me accurate dimensions on the mounting-base and it's pattern of drilled holes, my digital-caliper confirmed what should be a perfect fit. And it was indeed! No bolts for mounting are provided, though I suggested GSO should include these, and the bolts for the old one were too short for the thicker base, where they are recessed nicely - I had to scavange some nuts & bolts from my parts-drawer. In short order, it was attached. A trip to my local hardware-store will hopefully provide me with some black-anodyzed 16mm M4's.

This 1.25" Crayford is of a shorter profile than the old R & P. But the travel of the draw-tube more than makes up for that - 47.98mm vs. 36.37mm - and the tension-bolt gives me all-points from letting go will drop it like a rock, to it's needing a hammer to make it so much as twitch. And all-points-between.

My conclusions - GSO has done it again. While some of their astro-goodies were not too good a few years back, I haven't been disappointed with anything from them in recent memory. Especially their Crayford-Focusers. I was a bit apprehensive with this being a single-speed, having gotten used to their 10:1 two-speed models of late, my concern was unwarranted. This Crayford is as smooth as silk. I keep a BORG two-piece helical-focuser on hand for any problems, but I see it's layer of dust will continue to thicken for the foreseeable future. It certainly won't see any purpose on this single-speed Crayford. I'm quite impressed!

Stay sharp -

Dave

 

 

 

[Guest]

Hey there Dave,

I got this exact same one from the exact same supplier, came across the pond in about 7 working days its a perfect upgrade to my 150p StarDiscovery.

Great post pal.

Lee.

[nightfisher]

Dave, nice write and thanks for posting

[carlpenn]

On 01/05/2016 at 21:44, LeeRich said:

Hey there Dave,

I got this exact same one from the exact same supplier, came across the pond in about 7 working days its a perfect upgrade to my 150p StarDiscovery.

Great post pal.

Lee.

Hi Lee, did this Focuser fit out the box or did you have to make any alterations? I am looking to upgrade my SW 150p focuser

[Guest]

Hi Carl.

No...The star discovery focuser only has 3 screw holes and the GSO like many other better focusers have four so I had to measure and drill these four new holes and then widen the draw tube opening by about 5 mm with a dremmel.  I made a template first then just got stuck in lol 

[carlpenn]

17 minutes ago, LeeRich said:

Hi Carl.

No...The star discovery focuser only has 3 screw holes and the GSO like many other better focusers have four so I had to measure and drill these four new holes and then widen the draw tube opening by about 5 mm with a dremmel.  I made a template first then just got stuck in lol 

Cheers Lee. Hadn't noticed the focuser having only 3 screws!! 

 

[ollypenrice]

Personally I don't use the slow motion knob on any of our scopes for visual. I don't find I can detect enough difference in the view quickly enough to feel confident. I'm happy with coarse focus, even in our F4.1 Dob. Maybe if I used a fast scope for planetary I might feel differently and I may well be in a minority here anyway. While I think the Crayford is fundamentally flawed for heavy camera imaging it can be perfectly nice for visual if it's made properly, as you say this one is.

Olly