Esprit120ED / QHY Q-Focuser HP

[paulh235]

Hi all,

I am running into a problem installing this automatic focuser onto this scope. The issue is that the Esprit fine focus shaft is 2mm in diameter and the Q-Focuser kit includes a 5mm - 3/4/5mm.

Has anyone else run into this problem? 

For Esprit120 owners, which automatic focuser do you use, and is it installed on the coarse side or the fine side of the Esprit focuser?

Thanks in advance for the assist!

 

 

 

[ollypenrice]

I think it's more usual to mount a motor focus on the fast focus shaft. Could you do that? (The motor can move in tiny increments and reducing backlash is good.)

Olly

[Laurin Dave]

I use a Lakeside on both my Esprit100 and  my 150.. (the 120 has the same focuser)  it goes on the coarse side

Dave

[david_taurus83]

The Esprit focuser is rack and pinion but only on the course side. The fine focuser mechanism is a sort of Crayford type design. I had an auto focuser on this for a while but the fine focus started slipping. I had to change to an auto focuser to fit the course side. Not all auto focus units have the torque to move the course side though.

[saac]

@paulh235 I use a ZWO auto focuser on my Esprit120.  As Olly and Laurin have suggested, I also have it mounted onto the course focusing side.  I haven't used it much in anger but from what use it has had there have been no problems, it operates well. 

Jim 

Edited January 10 by saac

[paulh235]

Thanks! I was very surprised to see the directions for install on the fine focus side, too. In fact, I've not heard of this before. I have used the ZWO box on my (old) Evostar120 with no problems, on the coarse side, of course.

I will look in to the Lakeside.

@david_taurus83 Curious, which brand of focuser did you use on the fine side? On the coarse side? In the photo, could you point me to the correct place to loosen the coarse knob? I only see a set screw on number 2. Number 1 appears to not have a set screw as I rotate the knob a full 360. The other side has the knobs removed. It's as far as I've gotten. 

Thank you, thank you, and thank you!

[paulh235]

BTW, my fallback plan is to use an appropriately sized coupler that was 3D printed by my friend. But, I am really hesitant to use that as a permanent solution.

[david_taurus83]

I had a DSD AF3 which uses a belt around the focus knob. The AF3 itself worked flawlessly, it is the Esprit fine focus mechanism that wasn't up to the task.

The course knob does have a grub screw. You need to turn it to access it through no 1 hole I believe.

[Richard_]

The new QHY focuser comes in two flavours: standard version and High Precision version. The standard version attaches to the coarse focus knob whilst the High Precision version (per OP) attaches to the fine focus knob. Fine focus shafts tend to have a narrower OD's compared with coarse focus shafts so I'm surprised that QHY didn't include appropriately sized couplers with the HP version.

@paulh235, were any adapters included in your fine focuser package other than the standard sized couplers? In the past, I have used the Sesto Senso 2 on the fine focus shaft of my WO FLT120 and an adapter was provided which linked the coupler to the fine focus shaft (see Fig.8 to Fig.14 in the below thread I made). Are the QHY versions meant to ship with these, or are they available for purchase?

 

[paulh235]

2 hours ago, Richard_ said:

The new QHY focuser comes in two flavours: standard version and High Precision version. The standard version attaches to the coarse focus knob whilst the High Precision version (per OP) attaches to the fine focus knob. Fine focus shafts tend to have a narrower OD's compared with coarse focus shafts so I'm surprised that QHY didn't include appropriately sized couplers with the HP version.

@paulh235, were any adapters included in your fine focuser package other than the standard sized couplers? In the past, I have used the Sesto Senso 2 on the fine focus shaft of my WO FLT120 and an adapter was provided which linked the coupler to the fine focus shaft (see Fig.8 to Fig.14 in the below thread I made). Are the QHY versions meant to ship with these, or are they available for purchase?

 

Yes - I am also surprised that it wasn't included. I still have a query pending to QHY with that exact question: are they available for purchase? According to SW support the fine shaft is 2mm - coarse is larger. There are 3 couplers(5mm - 3/4/5mm) included with the QHY kit, as well as screws, bracket, and bracket stand-offs. I hope to hear back from QHY soon.

I have a 3D printed coupler from a friend, now, who has this same problem, but on two scopes (WO FLT132 and a SW Newtonian.) He put setscrews into it, made from polycarbonate. I will install it tomorrow and then wait for the rest of my upgrades to arrive and put the new scope and image train on a mount. I followup...

[ollypenrice]

I wonder what problem they were trying to solve by offering a fine focus solution? 

Olly

[Richard_]

8 hours ago, paulh235 said:

Yes - I am also surprised that it wasn't included. I still have a query pending to QHY with that exact question: are they available for purchase? According to SW support the fine shaft is 2mm - coarse is larger. There are 3 couplers(5mm - 3/4/5mm) included with the QHY kit, as well as screws, bracket, and bracket stand-offs. I hope to hear back from QHY soon.

I have a 3D printed coupler from a friend, now, who has this same problem, but on two scopes (WO FLT132 and a SW Newtonian.) He put setscrews into it, made from polycarbonate. I will install it tomorrow and then wait for the rest of my upgrades to arrive and put the new scope and image train on a mount. I followup...

It'll be interesting to see if those polycarbonate set screws will work. In my experience with the Sesto Senso and a refractor, the weight of my camera (ASI533) overcame the friction between the steel set screws which resulted in slippage (ie the auto focuser is rotating but the focus shaft is not). It may not be a problem if you're imaging at lower altitudes but as you approach the zenith, the problem gets worse or even if you're using a heavier mono setup with filter wheel. 

Hopefully this isn't the case with your scope and everything works OK. But if you see issues, I would hazard a guess it would be due to slippage. 

[Laurin Dave]

1 hour ago, ollypenrice said:

I wonder what problem they were trying to solve by offering a fine focus solution? 

Olly

Indeed ...  my Lakesides are both set to  25 steps between focus points.  Be interesting to know how many steps the focusers designed for the fine side need. 

[ollypenrice]

1 minute ago, Laurin Dave said:

Indeed ...  my Lakesides are both set to  25 steps between focus points.  Be interesting to know how many steps the focusers designed for the fine side need. 

The Vincent motorcycle was described as 'A solution looking for a problem.' I think we see that here...

Olly

[david_taurus83]

If possible, I would be looking at returning the QHY unit and swapping for something that can go on the course side. In my experience, the Esprit fine focus design is not up to the task of imaging. It is essentially a Crayford design and will eventually start slipping.

[paulh235]

5 hours ago, david_taurus83 said:

If possible, I would be looking at returning the QHY unit and swapping for something that can go on the course side. In my experience, the Esprit fine focus design is not up to the task of imaging. It is essentially a Crayford design and will eventually start slipping.

I am arriving at this same conclusion. QHY Support is unresponsive. The home-fabricated solution just seems sketchy to me. BTW, my image train (flattener, rotator, filter wheel, qhy268m) weighs about 2.5kg.) This is less than half the specification for the HP, and the regular version I think has a max weight of 7.5kg.

[paulh235]

Okay - it's done. Q-Focuser returned, Focuscube3 shipping. Thanks for the dialog folks, it really helps!

 

Cheers,

--Paul

[Richard_]

9 minutes ago, paulh235 said:

Okay - it's done. Q-Focuser returned, Focuscube3 shipping. Thanks for the dialog folks, it really helps!

 

Cheers,

--Paul

Good choice! I've got the Focus Cube v2 on my FLT120 and it works great. 

[paulh235]

To conclude, in the pic above, the coarse knob set screw is accessed through hole #2. 

Edited January 12 by paulh235
typo

[Stuart1971]

On 11/01/2024 at 18:10, paulh235 said:

To conclude, in the pic above, the coarse knob set screw is accessed through hole #2. 

Can I ask why you did not just swap it for the version that QHY supply that fits the coarse side of your focuser…?

The precision one you purchased was to fit the fine focus knob, they made this for 2 reasons, 

1. It has zero backlash as there are no reduction gears inside, so is a coarser focuser, but is compensated for, by the fact it’s fitted to the fine focus side of the focuser..

2. It has a clutch and a manual adjustment knob for manual focus override.