Calling SW Esprit 120 owners - guiding advice needed

[b36lbx]

I recently purchased an Esprit 120 and looking for some guiding setup recommendations.

Do you use and OAG or a guide scope on top? If you use a OAG - which one and please share back focus setup, including filters.

Do you use a guide scope - which one and what did you use the attach it on top on the Esprit?

Please share detailed pics of you set-up if possible.

Many thanks.

[newbie alert]

At 840mm fl you could do either and both would work  oag are harder to initially setup and needs a fairly sensitive camera

[cfinn]

On 22/05/2021 at 16:45, b36lbx said:

I recently purchased an Esprit 120 and looking for some guiding setup recommendations.

Do you use and OAG or a guide scope on top? If you use a OAG - which one and please share back focus setup, including filters.

Do you use a guide scope - which one and what did you use the attach it on top on the Esprit?

Please share detailed pics of you set-up if possible.

Many thanks.

I use an EvoGuide 50ED with ASI 120MM Mini riding on top and it works great. To attach it I have a 15” universal dovetail and use a pair of Losmandy female to Vixen female clamps. I’m including a photo below so you can see what this looks like. It’s very rigid, which you want to minimise differential flexure, but comes with the disadvantage of adding more weight. Note that I also have a Pegasus Pocket Powerbox Advance attached using a pair of additional clamps. All of this together with the imaging camera, filter wheel etc gives a total weight of nearly 17kg, necessitating the use of the counterweight extension shaft on my EQ6R. This gives a bigger moment of inertia and amplifies the guiding RMS in RA slightly, though I am still sub-arcsecond with careful balancing. To counter this, I have a couple of additional counterweights on order to negate the need for the shaft extension and achieve balance closer to the mount. Just something to be aware of. An OAG will definitely save on weight but may be harder to use (accounts vary) and gives a narrower FOV, which means fewer guide stars and less opportunity to use recent advancements in guiding (multi star).

Charles

[b36lbx]

1 hour ago, cfinn said:

I use an EvoGuide 50ED with ASI 120MM Mini riding on top and it works great. To attach it I have a 15” universal dovetail and use a pair of Losmandy female to Vixen female clamps. I’m including a photo below so you can see what this looks like. It’s very rigid, which you want to minimise differential flexure, but comes with the disadvantage of adding more weight. Note that I also have a Pegasus Pocket Powerbox Advance attached using a pair of additional clamps. All of this together with the imaging camera, filter wheel etc gives a total weight of nearly 17kg, necessitating the use of the counterweight extension shaft on my EQ6R. This gives a bigger moment of inertia and amplifies the guiding RMS in RA slightly, though I am still sub-arcsecond with careful balancing. To counter this, I have a couple of additional counterweights on order to negate the need for the shaft extension and achieve balance closer to the mount. Just something to be aware of. An OAG will definitely save on weight but may be harder to use (accounts vary) and gives a narrower FOV, which means fewer guide stars and less opportunity to use recent advancements in guiding (multi star).

Charles

Hey Charles,

Very useful response, thank you very much. You are absolutely right multi star is my main concern with the OAG. If I could only be able to get the right back focus with my Celestron OAG so I could try it but it is not possible.

As a side note, I use 3 counterweights with my EdgeHD, positioned further up, I found this to work a lot better and give better results than 2 weights with the extension attached.

Bogdan

 

[cfinn]

3 minutes ago, b36lbx said:

Hey Charles,

Very useful response, thank you very much. You are absolutely right multi star is my main concern with the OAG. If I could only be able to get the right back focus with my Celestron OAG so I could try it but it is not possible.

As a side note, I use 3 counterweights with my EdgeHD, positioned further up, I found this to work a lot better and give better results than 2 weights with the extension attached.

Bogdan

 

Hi Bogdan,

No problem. Good to know you have better results with the extra counterweight. The physics suggests this should be the case but nice to hear it works in reality. 

Charles

[newbie alert]

Hey Charles,

Very useful response, thank you very much. You are absolutely right multi star is my main concern with the OAG. If I could only be able to get the right back focus with my Celestron OAG so I could try it but it is not possible.

With the celestron OAG you may need to get a m48 to sct adapter, as I did with mine

And regarding the camera yes it needs to be fairly sensitive , I'm using a qhy 290 with a sct

[b36lbx]

20 hours ago, newbie alert said:

Hey Charles,

Very useful response, thank you very much. You are absolutely right multi star is my main concern with the OAG. If I could only be able to get the right back focus with my Celestron OAG so I could try it but it is not possible.

With the celestron OAG you may need to get a m48 to sct adapter, as I did with mine

And regarding the camera yes it needs to be fairly sensitive , I'm using a qhy 290 with a sct

Hey, thanks for the info.

I am very interested in some detail (and pictures if possible) about the adapter on the telescope side. The configuration I've tried is as follows: 20mm - 2 part M62 to M48 adapter included with the flattener + 4.5mm flat female M48 OAG adapter + 29mm OAG body + 4.5mm flat female M42 OAG adapter = 58mm + 17.5mm 2600mm = 75.5mm and I'm still left with needing a M42 male to male adapter to connect the camera to the last bit of the OAG, that will add at least another 2mm so 77.5mm, the back focus of the 120 flattener is 75mm.

On the camera - I use a 290mm mini I believe this is the ZWO equivalent to yours.

[newbie alert]

On 24/05/2021 at 19:32, b36lbx said:

Hey, thanks for the info.

I am very interested in some detail (and pictures if possible) about the adapter on the telescope side. The configuration I've tried is as follows: 20mm - 2 part M62 to M48 adapter included with the flattener + 4.5mm flat female M48 OAG adapter + 29mm OAG body + 4.5mm flat female M42 OAG adapter = 58mm + 17.5mm 2600mm = 75.5mm and I'm still left with needing a M42 male to male adapter to connect the camera to the last bit of the OAG, that will add at least another 2mm so 77.5mm, the back focus of the 120 flattener is 75mm.

On the camera - I use a 290mm mini I believe this is the ZWO equivalent to yours.

Somehow I thought you was using a sct 🤔.. but for my esprit 80 which has  a shorter back focus than yours.. I can't remember the adapters that I used and I'm sure that my starlight xpress filterwheel has m42 fittings, male one side and female the other..

But I try to help best I can .. your adapter to adapter fittings are adding valuable spacing , I also used 2/3rds your filter thickness and I'm pretty much spot on.. if you use spacing shims then I'd advise on using metal ones( baader) as the delrins I had as well as not fitting partically well are different thicknesses at different parts of its circumference, and introduced tilt..