APO Refractor Recommendations

[JayStar]

Reaching out to the board to get some recommendations on an APO refractor.

I have recently purchased a decent mount that can handle around 50kg of weight.  I was going to de-fork my CPC925 and use the OTA, but I am keen to do more DSO imaging at shorter focal lengths.  The CPC925 can do a good job on planets but for DSO it's really hard work!  The plan is to keep the 925 for planets and get a good APO.

Current situation:

- Live in a Bortle 5 area

- Have a Skyshed Pod in the back yard - limited views North West and restricted views below about 15 degrees AZ - Pod is 8ft * 8ft internally, fixed pier centrally

- pier and scope will be permanently placed - but I will occasionally swap the OTS between the 925 and APO. Don't want to mount both at the same time even if I could.

- Voyager and TheSkyX Pro software (automation of dome not possible with Pod - but intend to automate everything else so availability of focus motors / rotators etc for any scope will be important)

- Want to use a fairly small FL guide scope

 I have been looking at the Esprit 150 as an option.  What I am not sure about is whether it might be too much in terms of space inside an 8*8 POD and also whether I really need 150mm aperture given I will be using the 925 for planetary (or an I wrong there? i.e. would the 150 be good for planetary too?).  Would an Esprit 120 be just as good, or maybe another 120 or 150 from a different manufacturer.  I am not sure whether the SkyWatcher scopes are just good for the money or just plain good regardless of the cheaper price.  Would I, for example, be better with a 120 Williams Optics scope as opposed to the 150 SkyWacther in terms of quality of optics and build?  How about other brands?

My budget is c£4.500 for the scope only 

[ollypenrice]

You could probably find a TEC 140 on the used market for that. However, the Esprits are not just good value, they're very good scopes. I'd personally go for them over WO.

Two things to consider: what FOV do you want? With modern small-pixel cameras a one metre FL gets you right into the small galaxies. This is the TEC at 1015mm FL with an Atik 460.

https://www.astrobin.com/full/393219/0/

But you might prefer something to cover more sky without a mosaic.

The other thing is the size of the corrected circle. If you ever intend to use a full frame camera you'll need a corrected circle of at least 44mm with flattener. I would check this out and also confirm that it really does work by looking at posted images. Tak claim the Baby Q will cover full frame. It won't.

Olly

[alan potts]

A couple of my fellow Mods have SW Esprit 150's and they turn out some stunning images. I wish I had bought one when I could have out here for 3400, the dealer here is a friend, sadly he is not in business now. Olly has done some stunning captures with his TEC 140's too

I have also heard very good reports for the 120mm too, which if I am honest would be more my upgrade now for F/L reasons.

Alan

[JayStar]

1 hour ago, ollypenrice said:

You could probably find a TEC 140 on the used market for that. However, the Esprits are not just good value, they're very good scopes. I'd personally go for them over WO.

Two things to consider: what FOV do you want? With modern small-pixel cameras a one metre FL gets you right into the small galaxies. This is the TEC at 1015mm FL with an Atik 460.

https://www.astrobin.com/full/393219/0/

But you might prefer something to cover more sky without a mosaic.

The other thing is the size of the corrected circle. If you ever intend to use a full frame camera you'll need a corrected circle of at least 44mm with flattener. I would check this out and also confirm that it really does work by looking at posted images. Tak claim the Baby Q will cover full frame. It won't.

Olly

I will check out the TEC.  A new 140 is not that much more than a Esprit 150. (but would be above budget... I am trying to stick to budget but often fail miserably  )

Good point on FOV.  I was thinking that I would get a smaller doublet to do a dual job of guiding and also wider field. For example a SW ED Pro 72 at 450mm FL.

I also don't mind mosaics - in fact quite enjoy the process I am learning in Voyager for automation.

Thanks for the tip on checking the full frame... will do that (and not with the manufacturer).

 

 

 

[JayStar]

53 minutes ago, alan potts said:

A couple of my fellow Mods have SW Esprit 150's and they turn out some stunning images. I wish I had bought one when I could have out here for 3400, the dealer here is a friend, sadly he is not in business now. Olly has done some stunning captures with his TEC 140's too

I have also heard very good reports for the 120mm too, which if I am honest would be more my upgrade now for F/L reasons.

Alan

The Esprit 120 might end up being the best option as it has to fit in the Obsy - that is something I still need to get clear on .. whether a 150 can slew unimpeded by walls, dome ceiling.  8*8 seems quite tight given the scope dimensions, but hard to estimate.

 

[Sp@ce_d]

+1 for the Esprits. I have three, 2x80's and recently my wife treated me to a 150 ( special birthday pressie  for moving up a decade!) which I am loving. I've had WO's in the past but from my experience (I didn't like the star shapes/cell clips or focusers) the Esprits out do them. The Esprit 150 with the new Reducer/Flattener 0.77x is a nice match with my QSI683. Not sure how much vignetting there'll be on a full frame though as it won't fully illuminate. I tried doing DSO with my C925 but wasted a year really.. mirror flop & constant collation probs. It's brilliant for observing but unless you can lock the mirrors (HD version) I wouldn't waste the time for imaging. I replaced it with a carbon RC8 which stayed on the mount for 5 years!.. However I prefer the Esprit150 hands down. My setup comes in at about 4feet in length from dew shield extended to back of camera, so you'll need at least enough room to swing that around.

Edit: I'd suggest you go OAG rather than separate guidescope.

Edited December 14, 2020 by Sp@ce_d
Added advice for guide scope options

[Laurin Dave]

The Esprits are very good (I have two a 150 and a 100) ..  as Olly says the crucial question you need to ask yourself is what fov do you want.  What camera do you intend to use ?  The 150 (or a TEC140) is great for galaxies but needs a large (ie APSH or Full Frame I have an SX-46 ) sensor to capture decent areas of the most popular nebulae, (and may require a focuser upgrade to cope with the weight).   It can do planets but when I tried on Jupiter  the images were someway short of those taken with my 20 year old 10" LX200.   As for doing mosaics my experience is that I can get them to work in narrowband but not LRGB as the gradients (I image from Bortle4/5) are just too much to deal with...  as a result of this the Esprit150 is on the linen cupboard, the SX46 is on the Esprit100 and is dual scoped with a WOGT71/ASI1600.  

Dave

 

[Miguel1983]

Another +1 for the Esprit, i've got the 120 and i'd love to add the 150 to my collection, but i'll need a bigger mount first.... 

I use the 120 at native 840mm and reduced at 630mm, got a TS76EDPH at 342mm so the Esprit 100 would also fit nicely in between there 🤓 .

Lots of options for reducers too, Apex 0,65 from starizona, TS has some good ones and SW just released their 0,77x for the 120 and 150.

Good luck choosing !

[JayStar]

1 hour ago, Laurin Dave said:

The Esprits are very good (I have two a 150 and a 100) ..  as Olly says the crucial question you need to ask yourself is what fov do you want.  What camera do you intend to use ?  The 150 (or a TEC140) is great for galaxies but needs a large (ie APSH or Full Frame I have an SX-46 ) sensor to capture decent areas of the most popular nebulae, (and may require a focuser upgrade to cope with the weight).   It can do planets but when I tried on Jupiter  the images were someway short of those taken with my 20 year old 10" LX200.   As for doing mosaics my experience is that I can get them to work in narrowband but not LRGB as the gradients (I image from Bortle4/5) are just too much to deal with...  as a result of this the Esprit150 is on the linen cupboard, the SX46 is on the Esprit100 and is dual scoped with a WOGT71/ASI1600.  

Dave

 

In terms of FOV - I seem to live on the astronomytools calculator   With the ASI1600 and Esprit 150 it seems fine for me - as long as I have some options of a smaller scope with a wider FOV also. But then the cost starts ramping up.

Dave - camera is an ASI1600 Pro - so not full frame.  Would like the scope to be able to use a full frame camera in the future.

I guess there are lots of options - I could go with a combo of the smaller Esprit 120 and a full frame camera as an option for similar cost overall.  The 120 is advertised at being handle full frame...sounds like your 100 can also? 

There is already some fab advice in this thread and I am actually already pulling myself back from the Esprit 150.  I am no expert and have had a terrible time trying to get anything working with the CPC925, even with the reducer. Floppy mirror, hard to guide, 2350FL etc... Maybe going to a 1050mm FL Frac is not the best step for someone of my skill. The 120 is less than half the price and is 850mm FL.  I could actually get that and another camera (full frame) which would give me more options on FOV.  I guess the 120 will need longer exposures than the 150, but I am hoping my new mount when it arrives will be up to it.

I will be keeping my 9.25 SCT for planets.

 

Edited December 14, 2020 by JayStar

[JayStar]

2 hours ago, Sp@ce_d said:

The Esprit 150 with the new Reducer/Flattener 0.77x is a nice match with my QSI683. Not sure how much vignetting there'll be on a full frame though as it won't fully illuminate.

Can you elaborate here? Is the vignetting only with the reducer?

2 hours ago, Sp@ce_d said:

I tried doing DSO with my C925 but wasted a year really.. mirror flop & constant collation probs.

I hear you! I've wasted more than a year trying.  Live and learn

 

2 hours ago, Sp@ce_d said:

I'd suggest you go OAG rather than separate guidescope.

I have an OAG.. Like to have both options, though - oag and guidescope, as finding stars can be a problem (at least for me) with an OAG.

 

[Sp@ce_d]

6 minutes ago, JayStar said:

Can you elaborate here? Is the vignetting only with the reducer?

I have an OAG.. Like to have both options, though - oag and guidescope, as finding stars can be a problem (at least for me) with an OAG.

 

With the Flattener the image circle is 44mm

With the new 0.77x Red/Flat it's 36mm

So the 36mm will vignette but I don't have a full frame camera so can't say what the 44mm will be like.

You do need a sensitive guide camera. With guiding flex is an issue you want to avoid at longer FL & TBH I never had an issue with either the QSI inbuilt or the SX filter wheel/OAG combo with a lodestar. I use multistar guiding now which has improved even more (ACP/Maxim). The RC8 did complain a couple of times on M51 a few years back if it wasn't a good sky but can't remember having issues anywhere else.. not yet anyway & I've been using OAG's for years now. However obviously the longer FL you go the more you'll have to plan for the guide star. 

[newbie alert]

I love these sort of threads, spending other people's money ... the esprit 150 is a glorious scope as are the smaller versions..  what camera are you looking to combine it with? And just being nosey what 50kg class mount are you using?

[Miguel1983]

8 minutes ago, newbie alert said:

I love these sort of threads, spending other people's money ... 

 🤣

[JayStar]

30 minutes ago, newbie alert said:

I love these sort of threads, spending other people's money ... the esprit 150 is a glorious scope as are the smaller versions..  what camera are you looking to combine it with? And just being nosey what 50kg class mount are you using?

Camera is an ASI1600 Pro...so not full frame. Also have a Canon 700D

My new mount is ordered and will arrive some time in Jan, a CEM120 EC2.

Think I am probably headed down the Esprit 120 route.

 

Edited December 14, 2020 by JayStar

[Whirlwind]

It really depends on how wide you want to go - have you checked what sort of field of view you want?  The one thing to note is that large refractors can be burdensome on the mount and perhaps more so than a C925.  This is because the they are long and have large moments (especially when you add on the cameras).  Another thing to note is that many have flatteners or reducers but these have very limited backfocus so limits options for focusers/rotators/fwheels and OAG etc.

Did you also definitely want a refractor.  There are also things like the Tak Espsilon (130, 160, 180 all fall in the price range) which have pros and cons.

Other refractors that might be worth considering is the Vixen AX103S.  Yes it is only 4" but has a large backfocus of 130mm from the end of the drawtube.  It also has a dedicated reducer (it naturally has a flat field).  The FSQ85 has already been mentioned. The Tak TSA120 will also fall just in your budget (but the reducer would take it over the budget).  The TEC140 second hand as mentioned but are as rare as hens teeth.  Astrophysics 130ish or Tak106 scopes occasionally come up second hand as well.

[newbie alert]

1 hour ago, JayStar said:

Camera is an ASI1600 Pro...so not full frame. Also have a Canon 700D

My new mount is ordered and will arrive some time in Jan, a CEM120 EC2.

Think I am probably headed down the Esprit 120 route.

 

Nice mount, great scope... enjoy

[alan potts]

17 hours ago, JayStar said:

The Esprit 120 might end up being the best option as it has to fit in the Obsy - that is something I still need to get clear on .. whether a 150 can slew unimpeded by walls, dome ceiling.  8*8 seems quite tight given the scope dimensions, but hard to estimate.

 

It is a shame you are not near me, I have a length of 6 inch plastic sewer pipe I could cut to length and put in the mount to have a realistic dummy run before buying.

Alan

[JayStar]

6 minutes ago, alan potts said:

It is a shame you are not near me, I have a length of 6 inch plastic sewer pipe I could cut to length and put in the mount to have a realistic dummy run before buying.

Alan

Thanks for the thought there... I did some measuring last night and found the the 150 will fit based on the measurements and some aggressive assumptions on the imaging train length. Funny you mentioned the plastic pipe, that is what I used (not 6 inches wide but cut to length).  It is a tight fit, though.

That said, after the note from Olly, I spent a lot of time looking at the FOVs on astronomytools for both the 150 and the 120.  The 120 probably offers, for me, more options at the FOVs I want.  There is such a price differential that I could afford the 120 plus a good smaller refractor, plus the flatteners/reducers, for wider FOVs (and still be under my budget). No decision made yet (as my mount is not even here until the new year)  but currently thinking Esprit 120 plus something like the GT71 WO triplet.  With flatteners / reducers for both that gives FL options of 336, 420, 647, 840.  With an ASI1600 that gives me FOVs ranging from 1.21x0.91 degrees to 3.01x2.28 degrees.  For me that seems to work really well and will use my 9.25 for planets (and some tighter shots of galaxies/nebula if I really want to - and am able to!)

Overall, given the above, I think the 120 is the better option for me - even if the 150 is still incredibly desirable!

 

 

[alan potts]

39 minutes ago, JayStar said:

Thanks for the thought there... I did some measuring last night and found the the 150 will fit based on the measurements and some aggressive assumptions on the imaging train length. Funny you mentioned the plastic pipe, that is what I used (not 6 inches wide but cut to length).  It is a tight fit, though.

That said, after the note from Olly, I spent a lot of time looking at the FOVs on astronomytools for both the 150 and the 120.  The 120 probably offers, for me, more options at the FOVs I want.  There is such a price differential that I could afford the 120 plus a good smaller refractor, plus the flatteners/reducers, for wider FOVs (and still be under my budget). No decision made yet (as my mount is not even here until the new year)  but currently thinking Esprit 120 plus something like the GT71 WO triplet.  With flatteners / reducers for both that gives FL options of 336, 420, 647, 840.  With an ASI1600 that gives me FOVs ranging from 1.21x0.91 degrees to 3.01x2.28 degrees.  For me that seems to work really well and will use my 9.25 for planets (and some tighter shots of galaxies/nebula if I really want to - and am able to!)

Overall, given the above, I think the 120 is the better option for me - even if the 150 is still incredibly desirable!

 

 

Feel I would go for the 120mm, slightly shorter so a tad easier to guide, still very good quality optics and enough left from budget for a very nice camera or the bits you stated. I have 800mm, 635mm, 420mm and 330mm, as well as 1000m on a M/N 190mm that I have not used for AP yet, must try it, so pretty much the same as you. With me I spend so long getting polar alignment spot on I am reluctant to remove scope and swap around. 

Alan

[dan_adi]

On 14/12/2020 at 16:09, JayStar said:

Reaching out to the board to get some recommendations on an APO refractor.

I have recently purchased a decent mount that can handle around 50kg of weight.  I was going to de-fork my CPC925 and use the OTA, but I am keen to do more DSO imaging at shorter focal lengths.  The CPC925 can do a good job on planets but for DSO it's really hard work!  The plan is to keep the 925 for planets and get a good APO.

Current situation:

- Live in a Bortle 5 area

- Have a Skyshed Pod in the back yard - limited views North West and restricted views below about 15 degrees AZ - Pod is 8ft * 8ft internally, fixed pier centrally

- pier and scope will be permanently placed - but I will occasionally swap the OTS between the 925 and APO. Don't want to mount both at the same time even if I could.

- Voyager and TheSkyX Pro software (automation of dome not possible with Pod - but intend to automate everything else so availability of focus motors / rotators etc for any scope will be important)

- Want to use a fairly small FL guide scope

 I have been looking at the Esprit 150 as an option.  What I am not sure about is whether it might be too much in terms of space inside an 8*8 POD and also whether I really need 150mm aperture given I will be using the 925 for planetary (or an I wrong there? i.e. would the 150 be good for planetary too?).  Would an Esprit 120 be just as good, or maybe another 120 or 150 from a different manufacturer.  I am not sure whether the SkyWatcher scopes are just good for the money or just plain good regardless of the cheaper price.  Would I, for example, be better with a 120 Williams Optics scope as opposed to the 150 SkyWacther in terms of quality of optics and build?  How about other brands?

My budget is c£4.500 for the scope only 

Have you considered CFF refractors? Top quality, same as TEC or APM-LZOS. Their 140 mm APO is around 6000 EUR, close to your budget. They make their own field correctors (flatteners), and even adaptors for your camera. I received my 8 inch last week from them, but its been cloudy and rainy ever since so I can't test it, but from exterior inspection everything is perfect. https://cfftelescopes.eu/product/refractor-140-mm

Or if you want a triplet with some fluorite in it check  https://www.astro-theke.de/astro-optik-manufaktur/produkte/, Their 135 mm is around 7000 eur if I recall.

(I don't know if fluorite makes a big difference in imaging vs FPL53, we should ask some experts)

If I were you I would wait a little bit longer, and get a high quality refractor for imaging. You can't go wrong with a frac. I'm not saying the Esprit is bad or anything, but why not gather a little more cash and get the best one you can. Also, a high quality frac will keep its value over the years, so you can resale with little loss.

PS: Did the same mistake as you... have an 12 inch SCT and trying to dso image with it.... total frustration, never got it to work well so I ordered a refractor

Edited December 16, 2020 by dan_adi

[newbie alert]

On 15/12/2020 at 09:49, JayStar said:

Thanks for the thought there... I did some measuring last night and found the the 150 will fit based on the measurements and some aggressive assumptions on the imaging train length. Funny you mentioned the plastic pipe, that is what I used (not 6 inches wide but cut to length).  It is a tight fit, though.

That said, after the note from Olly, I spent a lot of time looking at the FOVs on astronomytools for both the 150 and the 120.  The 120 probably offers, for me, more options at the FOVs I want.  There is such a price differential that I could afford the 120 plus a good smaller refractor, plus the flatteners/reducers, for wider FOVs (and still be under my budget). No decision made yet (as my mount is not even here until the new year)  but currently thinking Esprit 120 plus something like the GT71 WO triplet.  With flatteners / reducers for both that gives FL options of 336, 420, 647, 840.  With an ASI1600 that gives me FOVs ranging from 1.21x0.91 degrees to 3.01x2.28 degrees.  For me that seems to work really well and will use my 9.25 for planets (and some tighter shots of galaxies/nebula if I really want to - and am able to!)

Overall, given the above, I think the 120 is the better option for me - even if the 150 is still incredibly desirable!

 

 

Why not a esprit 80.. 400mm fl instead of the W/O ?  That's what I'd do using your money

[JayStar]

2 minutes ago, newbie alert said:

Why not a esprit 80.. 400mm fl instead of the W/O ?  That's what I'd do using your money

Thought about it, but I am little turned off by the mounting... seems to be a bracket rather than rings.. for some reason I think it looks like it wouldn't be secure... I am sure that's just an impression, though.. no idea if true or not. 

Edited December 16, 2020 by JayStar

[newbie alert]

21 hours ago, JayStar said:

Thought about it, but I am little turned off by the mounting... seems to be a bracket rather than rings.. for some reason I think it looks like it wouldn't be secure... I am sure that's just an impression, though.. no idea if true or not. 

I just mounted mine on a dovetail, job done

[JayStar]

What do people think about Sharpstar?

There is a 121mm APO refractor, 121SDQ, available with built in flattener/reducer and a 60mm image circle that comes in a few hundred pounds above the Esprit 120, but still within budget.

Triplet with an additional two lenses in the flattener/reducer provides a FL of 678mm, f/5.6

It also has a 145mm backfocus.

Heard very little of the brand, however and not sure how they compare quality wise to SW.

Edited December 18, 2020 by JayStar

[mikemarotta]

On 14/12/2020 at 11:51, JayStar said:

In terms of FOV - I seem to live on the astronomytools calculator  

 

I had no idea. Thanks for the tip. I bookmarked it.

Mike M.