23 replies to this topic

[Lite2]

I love my new scope but although I am purely imaging I have noticed that the fine focus knob slips, like bad.

My purpose was solely to add the ZWO EAF but as far as I can tell the left "coarse" knob does not come off, I see no grub screws on it so I can't use the EAF. After taking the scope out the 1st night I got it I just winged it to test the scope out and it's great, at least for me. But very surprised of how weak the fine focus knob is, the coarse is working as it should. I am waiting on a reply from Mike/Astonomics about what may be wrong.

I have now ordered a Moonlite focuser so I can have my trusted stepper motor focus again,  but am curious as to any settings/adjustment that is off for the fine to slip that bad. I would have considered putting the EAF on the fine shaft but can't trust the slippage for my focus to be right. Nice looking focuser on the 102EDL but not up to the task of precise repeatable focus for imaging for me.

[bacon]

Something is definitely wrong here, mine has no perceptible slip or backlash.  The fine focus knob is excellent for visual use. 

I use a similar style electronic focuser and it works very well.  The coarse knob set screws are revealed by removing one of the focuser housing screws.  I hope you are able to get it fixed in a timely manner, it's disconcerting your focuser made it passed QC.

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[Redbetter]

Have you tried adjusting the tension balance for the fine focus knob?  I haven't seen images of the underside of the AT102EDL, but if the build of the rack and pinion is the same as the AT60ED and AT72EDII, then you might need to fine tune this.  I had problems out-of-the-box with the fine focus of the AT60ED.  I found an explanation of the screws and adjusted as described in post #299 in the following thread:  fine focus adjustment link.  AT72EDII didn't need adjustment from what I recall.  

 

Fine focus knobs have been a frequent source of fiddling over the decades, whether refractors or Dobs.  The fine focus can be more trouble than it is worth...until you finally get it dialed in.  Once dialed in I don't seem to have to mess with them again unless the focuser suffers some physical trauma.  A major problem is general lack of documentation about focuser adjustment.

[GSBass]

No issues with mine either, very nice and smooth, but I did take a picture showing underside, guess those 3 tiny screws are going to be the answer although I don’t guess it matters if the op has a moonlite on the way, I bet just one of those screws worked out just enough during shipment not to have solid contact on the gear teeth, actually probably the only thing it could be, a tiny turn should fix it

_____

update… just to keep anyone from having to research further, look at the picture of the 3 perpendicular screws… the middle one will adjust the tension for the fine focus, tighten, check, back off til you have a smooth travel

 

Have you tried adjusting the tension balance for the fine focus knob?  I haven't seen images of the underside of the AT102EDL, but if the build of the rack and pinion is the same as the AT60ED and AT72EDII, then you might need to fine tune this.  I had problems out-of-the-box with the fine focus of the AT60ED.  I found an explanation of the screws and adjusted as described in post #299 in the following thread:  fine focus adjustment link.  AT72EDII didn't need adjustment from what I recall.  

 

Fine focus knobs have been a frequent source of fiddling over the decades, whether refractors or Dobs.  The fine focus can be more trouble than it is worth...until you finally get it dialed in.  Once dialed in I don't seem to have to mess with them again unless the focuser suffers some physical trauma.  A major problem is general lack of documentation about focuser adjustment.

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Edited by GSBass, 15 May 2021 - 10:19 AM.

[Jon Isaacs]

There are a number of possible reasons the fine focuser is slipping. It could be as simple as a loose set screw on the knob or on the adapter between the two speed unit and the focuser body.  It could be an internal adjustment.

 

The Astro-tech focuser is a rack and pinion, the Moonlite is a Crayford, rack and pinion Focusers are generally preferred for astrophotography. 

 

Jon

[GSBass]

Sorry the op had an issue but have to say this is the nicest focuser I have ever had…. I mean super nice, can’t imagine a upgrade

There are a number of possible reasons the fine focuser is slipping. It could be as simple as a loose set screw on the knob or on the adapter between the two speed unit and the focuser body.  It could be an internal adjustment.

 

The Astro-tech focuser is a rack and pinion, the Moonlite is a Crayford, rack and pinion Focusers are generally preferred for astrophotography. 

 

Jon

[Redbetter]

Thanks for the pic of the bottom of the focuser.  It is the same arrangement as the other AT's I have.  The fine focus tension adjustment is the middle of the three screws.  It is a 2mm hex.  

[Lite2]

No issues with mine either, very nice and smooth, but I did take a picture showing underside, guess those 3 tiny screws are going to be the answer although I don’t guess it matters if the op has a moonlite on the way, I bet just one of those screws worked out just enough during shipment not to have solid contact on the gear teeth, actually probably the only thing it could be, a tiny turn should fix it

_____

update… just to keep anyone from having to research further, look at the picture of the 3 perpendicular screws… the middle one will adjust the tension for the fine focus, tighten, check, back off til you have a smooth travel

I did try the center of the 3 inline screws and it didn't help the fine focus.

Thanks for the tip Bacon on the access to the coarse knob, that worked and I have the EAF installed now so I will wait for the next clear night to test the auto focus in SGP to see if it works. I still think the resistance on the focuser is too tight, it just feels harder to move than any scope i've had.

Will put a hold on the Moonlite for now, but may just have to get it.

[Lite2]

Mike replied and just said to adjust/tighten the middle of the 3 screws but the fine focus is still loose so the Moonlite is on the way.

I had such high hopes for the focuser on this scope and although I did finally get the EAF installed I will stick with  the (to me) trusted Moonlite and sell the EAF.

It may work fine with the stock  + EAF but at this point I just don't trust the stock focuser.

I loved the focuser on my WOZ73 using the Moonlite Stepper motor but would likely trash the stock focuser from my 102. Glad everyone else is happy with theirs.

[Moondust]

I don't have an issue with the focuser on my 102EDL and it's presently working very smoothly. I did however notice that the fine focus knob was wobbling when I turned the course knob suggesting it was not on flush. I took it off and put it on several times with no improvement. I then noticed the hole where the fine knob slides onto the shaft is cut way too big so has a lot of play which is causing it to wobble. I wrapped some white plummers tape around the shaft a few times then reapplied the fine focus knob and no more wobble.   

[Lite2]

My 102 focuser is on the way to Mike/Astronomics to check out. My new Moonlite is great! Still waiting on a good night to test...

[Lite2]

My focuser from my 102edl is on the way to Mike to check out. I now have a Moonlite installed and finally got a few moments last night between the clouds.

My question now is for guidance as to how to adjust the tilt. In this shot from last night the right side don't look too bad but the left half of the frame is certainly "pointing" to the right side of the frame.

What is the methodology of discerning which way to move the imaging train? I have never been so picky as now to care, but now I do.

Do I move the focuser/camera into the "point" or away to correct? As in my example with the stars pointing to the right for the most part, what way should the imaging train move to compensate for that?

In other words, how to "steer" the eggs:).

Once I figure that out I would assume that then it's just a matter of spacing between the flattener and the camera to even the whole field.

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[daquad]

My focuser from my 102edl is on the way to Mike to check out. I now have a Moonlite installed and finally got a few moments last night between the clouds.

My question now is for guidance as to how to adjust the tilt. In this shot from last night the right side don't look too bad but the left half of the frame is certainly "pointing" to the right side of the frame.

What is the methodology of discerning which way to move the imaging train? I have never been so picky as now to care, but now I do.

Do I move the focuser/camera into the "point" or away to correct? As in my example with the stars pointing to the right for the most part, what way should the imaging train move to compensate for that?

In other words, how to "steer" the eggs:).

Once I figure that out I would assume that then it's just a matter of spacing between the flattener and the camera to even the whole field.

In that pic, looks to me like all stars are pointing downward and slightly to the left.  Guiding?

 

Dom Q.

[Lite2]

No issues with mine either, very nice and smooth, but I did take a picture showing underside, guess those 3 tiny screws are going to be the answer although I don’t guess it matters if the op has a moonlite on the way, I bet just one of those screws worked out just enough during shipment not to have solid contact on the gear teeth, actually probably the only thing it could be, a tiny turn should fix it

_____

update… just to keep anyone from having to research further, look at the picture of the 3 perpendicular screws… the middle one will adjust the tension for the fine focus, tighten, check, back off til you have a smooth travel

My trouble wasn't smoothness but slippage. The fine knob can't lift my imaging setup (1600, 5 filter wheel, OAG, FR). I sent the focuser back to Mike and he said he fixed it and said he was caught off guard about the new focuser design and was glad to know but to me it is still slipping a lot. I did get the Moonlite but am rethinking the need and the stock 102EDL focuser is ok on the course shaft so the fine knob is useless to me anyway. I want to use the ZWO EAF that I have so I am now looking for a threaded adapter for the stock focuser tube. It seems that I need a 62 to 48mm adapter but I am not positive that the tube is 62mm (that's my caliper measurement) but I don't seem to find a 62mm to 48mm threaded adapter anywhere. The stock compression ring has way too much wiggle for me so I want the camera all threaded. Is it a 63mm thread on the focuser tube? I see those listed.

Edited by Lite2, 05 June 2021 - 09:25 PM.

[Lite2]

I sent the Moonlite back (was hard to do), but for the extra weight the EAF on the stock focuser was the best choice not to mention about $300 less.

Had a short nite to test the EAF and although a crappy nite as far as clarity it seemed to work fine.

[Oldfracguy]

I love my new scope but although I am purely imaging I have noticed that the fine focus knob slips, like bad.

My purpose was solely to add the ZWO EAF but as far as I can tell the left "coarse" knob does not come off, I see no grub screws on it so I can't use the EAF. After taking the scope out the 1st night I got it I just winged it to test the scope out and it's great, at least for me. But very surprised of how weak the fine focus knob is, the coarse is working as it should. I am waiting on a reply from Mike/Astonomics about what may be wrong.

I have now ordered a Moonlite focuser so I can have my trusted stepper motor focus again,  but am curious as to any settings/adjustment that is off for the fine to slip that bad. I would have considered putting the EAF on the fine shaft but can't trust the slippage for my focus to be right. Nice looking focuser on the 102EDL but not up to the task of precise repeatable focus for imaging for me.

 

Mike replied and just said to adjust/tighten the middle of the 3 screws but the fine focus is still loose so the Moonlite is on the way.

I had such high hopes for the focuser on this scope and although I did finally get the EAF installed I will stick with  the (to me) trusted Moonlite and sell the EAF.

It may work fine with the stock  + EAF but at this point I just don't trust the stock focuser.

I loved the focuser on my WOZ73 using the Moonlite Stepper motor but would likely trash the stock focuser from my 102. Glad everyone else is happy with theirs.

 

I just received a scope with the same EDL style focuser, and it displayed the same symptoms.  Even after making the usual adjustments to the external Allen grub screws, includiing tightening that middle screw in the line of three as discussed, the fine focus knob would still slip when trying to lift a 2" diagonal and a 2" 38mm SWA eyepiece with the scope pointed upward at a high angle.  I had to remove the focuser and take it apart to get inside and then use snap ring pliers, alhough a small thin slotted screwdriver would probably work, and tighten the brass nut that is just inside the small bronze fitting with the three tiny Allen grub screws.  You need to hold the course focus knob tightly when snugging up that internal nut with the snap ring pliers.  When I reassembled and reinstalled the focuser and made the usual adjustments, I could actually yank on the 2" diagonal with the scope pointing straight up and the drawtube would not slip, yet the fine focus knob still was able to raise and lower the load as it is supposed to.

Edited by Oldfracguy, 14 September 2024 - 07:02 PM.

[Oldfracguy]

Here are some photos of the EDL focuser:

 

 

 

 

 

[Oldfracguy]

 

 

Edited by Oldfracguy, 14 September 2024 - 08:49 PM.

[Oldfracguy]

 

 

[Oldfracguy]

This is the internal adjustment that will stop the fine focus knob from slipping under load.  It is that nut just inside the bronze bushing on the shaft.  It has two long slots 180° apart.  You need some snap ring pliers or maybe a small thin screwdriver blade to turn that nut clockwise a litte to snug it up:

 

 

 

Edited by Oldfracguy, 14 September 2024 - 09:36 PM.

[Oldfracguy]

 

 

 

 

[Oldfracguy]

 

 

After all that, with a 2" diagonal and a heavy 2" wide-angle eyepiece and the scope pointing almost straight upward, I can yank on the diagonal and the drawtube will not slip one bit:

 

 

 

 

If I had three hands I would have taken a picture to show that how, even with me pulling downward on the diagonal, I could turn the fine focus knob with the other hand and still raise and lower the load with precision and smoothness.

Edited by Oldfracguy, 14 September 2024 - 09:32 PM.

[eyespy]

As one old frac guy to another, thank you for your photos concerning the dis-assembly of the EDL focuser. There are many grub screws etc on that focuser !! I have/had an issue with my focuser being a little too stiff to operate and the basic brass screw adjuster on top of the focuser in between the two finder mounts did nothing. Realizing from your photos that the focuser mechanism is held on by two 3mm socket screws that included spring washers, I loosened each of these half a turn and bingo, the focuser is now very smooth with perfect tension. Because of the spring washers, this minor adjustment slightly reduced the pressure between the rack and pinion without reducing the stability of the focuser mechanism attachment to the scope.

 

Thank you,

 

Doug…..

Edited by eyespy, 21 October 2024 - 05:01 PM.

[Oldfracguy]

You're most welcome, Doug.

 

The other design that Kunming United uses for their dual-speed rack-and-pinion focusers, such as those used on the Astro-Tech ATxxxEDT triplets, as well as other KUO-made ED scopes like the Willian Optics Zenithstars, are harder to "open up" to get inside, but is nonetheless equally outstanding.  Last year about this time I decided to put my money where my mouth was when I mentioned what these focusers are capable of doing, and why, in my humble opinion, MoonLite stopped making manual focusers:

 

 

 

Yes, that is a real brick hanging off the dual-speed R&P focuser of a William Optics Zenithstar 81.  The 2" William Optics diagonal with the 28mm UWA eyepiece along with the brick weighed a total of 3.72 kg, or 8.2 lbs.  Still, the load stayed in whatever position I set it, and the fine focus knob lifted it up and down with ease and precision.

Edited by Oldfracguy, 21 October 2024 - 07:30 PM.