Dual speed 2" Crayford focuser

[menacegtr 26]

Knighty2112  You are very welcome, i only wish i had a 2x Barlow to test for you. I am very pleased with it, getting that extra focus control is an absolute must when imaging or viewing the night sky. If i have to i would not hesitate in taking a bit off the back off our dear ST-120 scopes, it would be worth it, i will not count it out as something to do at a latter time

                                                              Dave:

[Knighty2112 3,978]

Just done some testing on my stock focuser using my 2" dielectric diagonal and combinations of EP's with and without my Omni 1.25" 2x Barlow. The average distance using a calipher to measure the distance from the tube of the focuser is around 20 to 22mm (measured to the inside points on the focuser) with my EP's and also with my 2x Barlow too. The shortest distance I get is when I use my 2x Barlow with a stock Skywatcher 20mm EP (which I rarely ever use at all), and with that combo I get a distance of just over 19mm outward travel required. I'm hoping that this minimum 19mm setting is big enough to cope with the extra length of the focuser so it will allow me to still be able to achieve focus still when using my 2" diagonal with my 2x Barlow and EP's. Of course I won't fully know if this is the case until I actually get the new focuser itself. Fingers crossed! 

Note; the image below shows just my 2" EP in the 2" diagonal, and not the 2x Barlow and 20mm EP which has the shortest outward travel of all my EP's with the 2x Barlow to achieve focus. 

Edited March 26, 2016 by Knighty2112

[menacegtr 26]

It will be interesting if you're 2x Barlow will achieve focus, as you've seen from one of my pictures were I left the focuser the last time I used the scope with my 5mm eyepiece without using my Barlow.  I would think for me to get focus it would require a lot more inward travel.  Do you think you will need a Barlow for your ST 120? I have 120x with a 5mm and 150x with a 4mm for me thats enough without adding low contrast and blurry views with higher magnification on the ST 120. If you have quality eyepieces I wouldn't worry to much about using your Barlow. Could you let me know the outcome with a 2x Barlow, it would be great if it works. But remember you can always revert back to your 1.25" diagonal to get in focus and still have a top focuser to fine tune

                                                                      Dave:

[Knighty2112 3,978]

Done all my number crunching for April, and I can just squeeze it in to get a focuser, so tomorrow I get to order it up when my wages go in. I'll see how my Barlow goes with the new focuser when it arrives.  

[Knighty2112 3,978]

Focuser ordered. Should arrive tomorrow hopefully!  

Yarggg! Got the date wrong! It arrives April 1st, so arrives Friday, not tomorrow as I first thought! Grrrr......????

Edited April 6, 2016 by Knighty2112

[Knighty2112 3,978]

Update: focuser arrived today April 1st (no joke!  ). Fitted like a glove into the telescope tube. Screwed in place within 5 minutes. Looks nice and dandy, and it is as smooth as silk when you focus it in and out. No slight play upwards like there was on the stock focuser. One thing I didn't realise about it was that you can rotate it around in the telescope too! Handy if you use an Equatorial mount with your refractor. You can just rotate the focuser around as you move your telescope around on the mount and always get it at the correct angle to view it (see pics below). This should stop you having to move the whole tube assembly or the EP and diagonal in the focuser. 

Tested it with my 2 x Barlow in as well on a distant chimney breast,  and I can achieve focus easily with all my EP's. I still have around 20mm inward focus if I need it too. All in all very happy so far with the focuser. Well worth the money paid. Now I just need to get a clear dark sky to go and and use it!  

Oh! And now I won't get sticky rack and pinion grease on my fingers accidentally when reaching out to focus the telescope in the dark like it used to happen with the stock focuser. That used to be so annoying! ? This focuser is free of that! ?

[Dave Lloyd 1,868]

That looks great, what's the best way to fit a finderscope or red dot?

[Knighty2112 3,978]

8 minutes ago, Dave Lloyd said:

That looks great, what's the best way to fit a finderscope or red dot?

Hi Dave. Ordered a new synta mounting shoe for my 6x30 finder. This will require to drill a couple of 3.5mm holes in the tube to attach it. Am going to place it as far back on the black telescope tube as possible. I'm thinking of also getting a Telrad Finder to fit too, but with that if I get one I will probably not screw it in place, but use large tie-wraps to hold it on. However, that is for next month if I go ahead with it. Now I just need some clear skies to test the focuser out on Jupiter or the Moon.  

[Dave Lloyd 1,868]

If you're flocking the tube you'll be killing two birds with one stone 

p.s awful saying.

[Knighty2112 3,978]

20 hours ago, Dave Lloyd said:

If you're flocking the tube you'll be killing two birds with one stone 

p.s awful saying.

Thanks to the prompt service by FLO I received my new synta finder scope shoe today. Drilled two new holes, fitted the new shoe and ready to go! Next weekend I plan to do the flocking!  

[menacegtr 26]

Knighty2112 wow so pleased you got the focuser to work with your Barlow, it would seem then that my 2.5x Barlow is to strong. I am glad you posted as I was in two minds to take an inch or so out of the back of the tube, and also I was wandering were to fit the  synta finder scope shoe, glad I didn't do any cutting. So all I need then is a 2x Barlow. are there any with the brass ring compression fitting, I don't like using the screw as the securing method as I don't want to mark my EP's. By the way do all your EP'S work ok with your 2x Barlow. And also is your diagonal a Altair Astro 2" Mirror Star Diagonal. If so that might be why I cannot get focus with my 2.5 Barlow, there might be a big difference in focal length between yours and my Skywatcher 2" Di-Electric Star Diagonal. I have four EP's ranging from 24x-60x-120x-150x without using a Barlow so I think I have all the magnification covered. If I need to go in-between or stronger than 150x I would have to put my SkyWatcher Deluxe Dielectric 90 Degree Star Diagonal 1.25" to get focus. You seem to have been lucky with your choice of diagonal, fair play to you and I am pleased you got the Crayford in the end, isn't it just day and night better than the standard focuser and yes none of that greezy shizzle

                                       Regards. Dave:

Edited April 5, 2016 by menacegtr

[Knighty2112 3,978]

9 hours ago, menacegtr said:

Knighty2112 wow so pleased you got the focuser to work with your Barlow, it would seem then that my 2.5x Barlow is to strong. I am glad you posted as I was in two minds to take an inch or so out of the back of the tube, and also I was wandering were to fit the  synta finder scope shoe, glad I didn't do any cutting. So all I need then is a 2x Barlow. are there any with the brass ring compression fitting, I don't like using the screw as the securing method as I don't want to mark my EP's. By the way do all your EP'S work ok with your 2x Barlow. And also is your diagonal a Altair Astro 2" Mirror Star Diagonal. If so that might be why I cannot get focus with my 2.5 Barlow, there might be a big difference in focal length between yours and my Skywatcher 2" Di-Electric Star Diagonal. I have four EP's ranging from 24x-60x-120x-150x without using a Barlow so I think I have all the magnification covered. If I need to go in-between or stronger than 150x I would have to put my SkyWatcher Deluxe Dielectric 90 Degree Star Diagonal 1.25" to get focus. You seem to have been lucky with your choice of diagonal, fair play to you and I am pleased you got the Crayford in the end, isn't it just day and night better than the standard focuser and yes none of that greezy shizzle

                                       Regards. Dave:

Hi Dave, I'm sure there are perhaps barlows with a compression ring rather than just the screw, but don't know of any as such. All my EP's ranging from 32mm down to 4.5mm work OK with the 2xbarlow too. The diagonal is a 2" Altair Astro diagonal too. Still awaiting some clear skies to test it out fully on stuff, but it is smooth as silk, so I don't think I'll have any issues with it. Supposed to be clear tonight, so going to check now to see if I can get the scope out.  

[menacegtr 26]

@Knighty2112 Thanks for the reply, I have spoke  the dealer I usually go with about our diagonals, he says because my diagonal is dielectric it may be demanding of a slightly longer focal length. it has come from the Sky Watcher ED range of scopes and also it is a bit longer as you insert the EP, mine looks thicker than yours. So what I have done is order the same diagonal that you have, 2" Altair Astro diagonal , I am just curious as to seeing if I can get the kind of forward focus that you have. I seem to have enough even with 150x mag but would like more headroom to be safe. I have also ordered a Sky watcher 4mm UWA now that I know a 4mm is not over kill.

                                                       Regards. Dave:

[Knighty2112 3,978]

1 hour ago, menacegtr said:

@Knighty2112 Thanks for the reply, I have spoke  the dealer I usually go with about our diagonals, he says because my diagonal is dielectric it may be demanding of a slightly longer focal length. it has come from the Sky Watcher ED range of scopes and also it is a bit longer as you insert the EP, mine looks thicker than yours. So what I have done is order the same diagonal that you have, 2" Altair Astro diagonal , I am just curious as to seeing if I can get the kind of forward focus that you have. I seem to have enough even with 150x mag but would like more headroom to be safe. I have also ordered a Sky watcher 4mm UWA now that I know a 4mm is not over kill.

                                                       Regards. Dave:

Here's where I got mine from. http://www.wexphotographic.com/buy-altair-astro-2-inch-quartz-dielectric-diagonal/p1543258, although I paid less than what they are asking for it now. 

Was out last night using the focuser for the first time on Jupiter and some galaxies too. Worked great. The fine control on the focuser means you can get spot on with your focusing (as long as good seeing conditions apply). The TMB Plantary II 4.5mm EP I have worked great on Jupiter.  

Edited April 6, 2016 by Knighty2112

[menacegtr 26]

I think I have just sussed why your getting forward focus, by the looks of your pics it looks like your EP'S are sitting much further inside your diagonal giving you more inward focus, is that the case

                         Dave:

[Knighty2112 3,978]

52 minutes ago, menacegtr said:

I think I have just sussed why your getting forward focus, by the looks of your pics it looks like your EP'S are sitting much further inside your diagonal giving you more inward focus, is that the case

                         Dave:

Hi Dave, I always put all my EP's as far into any diagonal or Barlow lens as far as they will fit into them with the EP collar. Do you not place your EP's in as deep as this, and only put them in so far in with some of the lower collar of the EP still poking up out of your diagonals? If that's so then that will affect your focal point and possibly also why you can't achieve focus with the focuser. Does your diagonal not allow you to push all of the EP collar into the diagonal?

Edited April 6, 2016 by Knighty2112

[menacegtr 26]

These are the 3 pics, 2 with the 1.25" fitted and not fitted. The other is the adaptor with one of my EP'S fitted as far as the collar will allow. Could you please post some pics of your diagonal with an eye piece, I want to see how far they go in, your diagonal seems to swallow them hole

                                                         Dave:

[Knighty2112 3,978]

25 minutes ago, menacegtr said:

These are the 3 pics, 2 with the 1.25" fitted and not fitted. The other is the adaptor with one of my EP'S fitted as far as the collar will allow. Could you please post some pics of your diagonal with an eye piece, I want to see how far they go in, your diagonal seems to swallow them hole

                                                         Dave:

Ah! Your 1.25" adapter to allow your 1.25" EP's be used in your diagonal seems to be quite large and add further height into the position of your EP above the diagonal itself. From the picture it seems like the 1.25"  adapter sits about 15 or 20mm higher, so this moves your 1.25" EP's further away from the focal point, meaning you have to compensate by having more inward focus. My 1.25" adapter on my diagonal doesn't alter the EP position at all as it has a well that allows the 1.25" EP's to sit into the diagonal at the same height, so there is no shift of the focal point position at all for either 2" or 1.25" EP's. Your diagonal moves your 1.25" EP's higher up due to the making of the 1.25" adapter that goes with it. I'll post a picture of my diagonal showing an EP fitted that sits in the well part of the 1.25" adapter. Hope that makes sense. 

Edited April 6, 2016 by Knighty2112

[Knighty2112 3,978]

OK, pictures of the 1.25" adapter supplied with my 2" diagonal in and out of the diagonal itself. The well that the EP's sit in when in the 1.25" adapter itself keeps the focul point of the EP's in the same position as when using  any 2" EP's, so there is no need to compensate for any diffence in the focuser itself when using 2" or 1.25" EP's. With your 1.25" adapter in your diagonal it moves the focal point further away when using your 1.25" EP's, hence you need to compensate for this by racking in more inward focus. Add in to this your Barlow too and this is most likely the major reason when using your Barlow that you can't achieve focus with it.

 

[menacegtr 26]

Thanks for that. you can understand my slightly muted response to my new focuser even though I can use it perfectly well with my Diagonal I am always at the back end of focus, around the 1 mark or just under. It makes perfect sense how you can have way more focus. I have ordered one  so I should look forward to extra inward focus should I need it, I hope it works as yours does. Thanks for posting the pictures

                                                 Dave:

[Knighty2112 3,978]

14 minutes ago, menacegtr said:

Thanks for that. you can understand my slightly muted response to my new focuser even though I can use it perfectly well with my Diagonal I am always at the back end of focus, around the 1 mark or just under. It makes perfect sense how you can have way more focus. I have ordered one  so I should look forward to extra inward focus should I need it, I hope it works as yours does. Thanks for posting the pictures

                                                 Dave:

I guess buying upgrades for your telescope that didn't come originally with the scope is similar to when you upgrade things on your PC too (motherboard, graphics card etc), and then find that some things don't work the same after the upgrade, or software doesn't run on it anymore. I hope the new diagonal lets you get focus with you Barlow lens in place too.  

[Knighty2112 3,978]

Update: Scope now fully flocked, and looks like the black hole of Calcutta in there now! ?

Now for some clear skies to test it out on some fuzzies!  

[JP-Astro 1]

Does it make much sense to upgrade such an inexpensive device as SW ST-120 with rather expensive parts such as GSO DS focuser?

[wookie1965 2,292]

I sorted out my lack of inward focus with one of these instead as the usual adapters.

https://www.firstlightoptics.com/adapters/baader-low-profile-eyepiece-adapter-for-steeltrack.html

 

 

[menacegtr 26]

@wookie1965Nice to see this thread is still active.Your link you posted looks like the part i should have ordered way back. I don't have problems with inward focus anymore as a result of the altair astro 2" diagonal. Still loving my st120mm and the super crayford focuser.