Is the Esprit 120 the Best 4" to 5" Telescope for AP ?

[Midnight_lightning]

Having spent weeks of research I am still trying to find my next telescope, something to give me a longer reach and better definition than my excellent Esprit 80/400. 

Good Star shape is especially important all the way into the corners.

I started looking at £2-3K scopes and am now also considering increasing the budget - here are my current candidates:

• Esprit 120
• APM 107/700
• Altair 115 ED
• APM LZOZ 115/805
• WO GT102
• Vixen SD 115 S
• TSA-120

Based on reviews and reading forum posts I expected the TSA-120 and APM LZOS 115 to come out strongly on top.

However having spent a day looking at images on the web taken with each of these scopes I have ranked them in order of teh ones I found had best star shape across the FOV - the results surprised me.

Many of these have good star shape near the centre but, even with a flattener or reducer, show marked stretch into the corners - particularly with full frame cameras. Astigmatism and mis-aligned colours were also noticeable even in the higher end scopes. 

It is highly subjective due to differences in flatteners, guiding, cropping, cameras, processing etc etc but I made notes as I went through the analysis and the Esprit 120 came out top and surprisingly the Tak didn't seem better than the cheaper scopes. In a blind test I would find it difficult to distinguish between most of these scopes although I suspect the Esprit 120 would do better than most.

I was hoping to find a light weight 115 or 120 to go on my HEQ5 but I'm now wondering whether to get the Esprit and use the c. £2500 I save to buy a stellar tuned EQ6 mount.

I would really like to hear your views if you use one of these scopes, and also please post see your images showing sharp round stars across the frame.

I'm happy to be proved wrong, I would rather stay with my HEQ5, and welcome any help in making a decision.

 

Edited May 3, 2020 by Midnight_lightning

[andrew s]

Surely your analysis is better than a range of opinions. Provided you sample was fair and reasonably comprehensive why  not go with the result?

Yes to more data but beware biasing the result.

Regards Andrew 

Edited May 3, 2020 by andrew s

[rl]

I think Andrew S's comment says it all. And spending the change on a chunkier mount with proven pedigree has to be a step up providing you're not planning to carry it around. .

On the other hand, playing devil's advocate, you have looked at the final results. Doubtless as objectively as possible. But has the ease with which those images have been obtained been considered? A lot of the scopes on that list are multi-use by design..both visual and AP.  You seem to be concentrating on the AP side of things. Would a dedicated astrograph be better, like a FSQ85/106? No flattener spacing to worry about, and a bit faster shortening exposure times? No back focus issues getting filter wheels in the chain et cetera...You can have a lot of frustration getting the scope/ flattener combo working properly if  you're pixel peeping for perfection in the corners.  The astrograph is a one-trick-pony but they do that trick exceedingly well. 

Some of this is a numbers game (apart from cost). Every premium scope will be checked over very thoroughly before leaving the factory and 99.9% will be perfect. The other 0.1% got dropped on the way. As for the ED120, I've never heard a bad word about them.....but I doubt if the QA is quite as good. But if you buy from a good dealer you can always change it if it's not up to snuff on arrival. 

I've never owned a premium refractor, and just having tried to argue the case for one...in truth I'm not convincing myself!

Edited May 3, 2020 by rl

[johninderby]

FLOs new StellaMira 104 would be worth considering. Bit better optics than the Esprit and better build quality.

https://www.firstlightoptics.com/stellamira-telescopes/stellamira-104mm-ed2-triplet-f6-25-apo-refractor-telescope.html

Will be interesting to see what results the IKI observatory gets with one.

 

[John]

I'm no imager but I can vouch for the LZOS optical quality from a visual point of view - I have a LZOS 130mm F/9.2 triplet refractor which has really superb optics.

 

[Big Bang!]

I have an Esprit 120ED Pro.  Utterly delighted, can't fault it.  I remember reading the reviews at the time I bought it that suggested it was essentially as good as anything else that most people can afford.  I bought the flattener with it at the time.

I have just upgraded my camera from an Atik One to an Atik 16200 to take advantage of the 44mm imaging circle this Esprit offers.  First light was two nights ago - round stars all the way to the corners.  

On the basis of my knowledge I would say the Esprit is very good value for money.

Gus

[Big Bang!]

This was the first un-guided test image (30 minutes) just to test the back focus on the Esprit/flattener/Atik combination - it might need a slight tweak; no cooling so hot pixels everywhere.  PixInsight Eccentricity puts it at .40

Gus

Edited May 3, 2020 by Big Bang!

[Midnight_lightning]

3 hours ago, rl said:

I think Andrew S's comment says it all. And spending the change on a chunkier mount with proven pedigree has to be a step up providing you're not planning to carry it around. .

On the other hand, playing devil's advocate, you have looked at the final results. Doubtless as objectively as possible. But has the ease with which those images have been obtained been considered? A lot of the scopes on that list are multi-use by design..both visual and AP.  You seem to be concentrating on the AP side of things. Would a dedicated astrograph be better, like a FSQ85/106? No flattener spacing to worry about, and a bit faster shortening exposure times? No back focus issues getting filter wheels in the chain et cetera...You can have a lot of frustration getting the scope/ flattener combo working properly if  you're pixel peeping for perfection in the corners.  The astrograph is a one-trick-pony but they do that trick exceedingly well. 

Some of this is a numbers game (apart from cost). Every premium scope will be checked over very thoroughly before leaving the factory and 99.9% will be perfect. The other 0.1% got dropped on the way. As for the ED120, I've never heard a bad word about them.....but I doubt if the QA is quite as good. But if you buy from a good dealer you can always change it if it's not up to snuff on arrival. 

I've never owned a premium refractor, and just having tried to argue the case for one...in truth I'm not convincing myself!

An EQ6 is certainly an option but I would rather stay with the HEQ5 if possible - its so good (c 0.21" RMS with my 80/400) and I currently leave everything set up indoors and just lift the whole thing out for imaging.

My analysis is massively subjective and I have no background to any of the images - the only thing I can say is that I looked at a lot of images before coming to a conclusion. That's why I am open to being corrected and would love to see high quality images from any of these scopes - preferably before people use software to make the stars round!

Back focus is a pain and I have gone to great lengths with my 80 - having to get complex custom adapters made. One of the massive advantages of the GT102 is the flattener/reducer has adjustment built in - just screw in/out to adjust BF. 

A key objective is to have a longer focal length say  600-800mm to pick off smaller targets and be able to use a reducer for larger targets.

I use an SX814 atm which is quite a smal chip but my next upgrade will be a larger chip, possibly one of the new full frame CMOS camera's which is why I am so keen to have round stars across the FOV - NO point in going full frame if non of these scopes can cope with it. They are all good in the centre but many soon trail off towards the edges.

 

 

[Midnight_lightning]

2 hours ago, johninderby said:

FLOs new StellaMira 104 would be worth considering. Bit better optics than the Esprit and better build quality.

 

I looked at that one early on and it is interesting but I would like a larger aperture and FL - also it's an unknown at this point which makes it more of a gamble.

 

[johninderby]

Yes that’s the problem with a new line if scopes. Hopefully FLO will expand the range in the future. 🙂

[Midnight_lightning]

34 minutes ago, Big Bang! said:

I have an Esprit 120ED Pro.  Utterly delighted, can't fault it.  I remember reading the reviews at the time I bought it that suggested it was essentially as good as anything else that most people can afford.  I bought the flattener with it at the time.

I have just upgraded my camera from an Atik One to an Atik 16200 to take advantage of the 44mm imaging circle this Esprit offers.  First light was two nights ago - round stars all the way to the corners.  

On the basis of my knowledge I would say the Esprit is very good value for money.

Gus

Part of my plan is to get to a FF sensor, good to know your stars are sharp with an APC-S. Be good to see your image

I bought my Esprit via Teleskop Express and it was tuned by a chap called Tommy (he's not there anymore). He stripped it down from new, collimated it, retaped the lens cell and provided reports - most of which went over my head but it recorded 94.4 strehl which I suspect isn't bad for a mass produced scope.

[Timebandit]

 

 

I have not read any negatives regarding the Esprit 120 . Actually they seem to get so many positive comments regarding being a top notch refractor at very sensible money.

But from your write up it sound that you have already answered the question yourself. As you seem to prefer the images of those taken with the Esprit when compared to other refractor images in your short list. Go for what images you already like , the Esprit

 

 

 

Edited May 3, 2020 by Timebandit

[Midnight_lightning]

30 minutes ago, Big Bang! said:

This was the first test image (30 minutes) just to test the back focus on the Esprit/flattener combination - it might need a slight tweak; no cooling so hot pixels everywhere.  PixInsight Eccentricity puts it at .40

Gus

That looks good, very like my smaller 80, and the star shapes are much better than most of the images I found on Astrobin 

[Skipper Billy]

I have heard that the Esprits are not too shy of Takahashi performance but if my Tak 106 was ever stolen or damaged I would buy the same again without a doubt - flat right into the corners even with a full frame sensor, zero spacing issues, tight round stars.

But will a HEQ5 do it justice??  Probably not - I would spend the money on the mount then look at a better scope.

Uncropped image attached - Tak 106 and Atik 16200

 

[Midnight_lightning]

2 minutes ago, Timebandit said:

 

 

I have not read any negatives regarding the Esprit 120 . Actually they seem to get so many positive comments regarding being a top notch refractor at very sensible money.

But from your write up it sound that you have already answered the question yourself. As you seem to prefer the images of those taken with the Esprit when compared to other refractor images in your short list. Go for what images you already like , the Esprit

 

 

 

Absolutely makes sense but this will almost certainly be the last scope I buy (Pension lump sum) so whilst I really like the Esprit I'm still hoping there is something even better if I spend a bit more. My very subjective evidence suggests maybe not but I'm still hoping someone proves me wrong. Also, I focused on Star Shape, some of these other scopes may be more or less sharper and have better/worse contrast.

 

[Midnight_lightning]

17 minutes ago, Skipper Billy said:

I have heard that the Esprits are not too shy of Takahashi performance but if my Tak 106 was ever stolen or damaged I would buy the same again without a doubt - flat right into the corners even with a full frame sensor, zero spacing issues, tight round stars.

But will a HEQ5 do it justice??  Probably not - I would spend the money on the mount then look at a better scope.

Uncropped image attached - Tak 106 and Atik 16200

 

Super image Skipper, seen a few of yours on UKAI

The 106Q is out of my budget  so I didn't look at it but just looking at a handful of 106q images on Astrobin and all of them had superb stars - much better than anything else I have looked at.

[Skipper Billy]

2 minutes ago, Midnight_lightning said:

The 106Q is out of my budget  so I didn't look at it

But you said ......

 

19 minutes ago, Midnight_lightning said:

I really like the Esprit I'm still hoping there is something even better if I spend a bit more.

Would you be looking at every sub and be thinking would it have been better with a Tak??

Just playing devils advocate! 😉 

[Midnight_lightning]

3 minutes ago, Skipper Billy said:

But you said ......

 

Would you be looking at every sub and be thinking would it have been better with a Tak??

Just playing devils advocate! 😉 

Pretty much. I will look at each sub and say, could it be better? What could I do to make it better? But I will also ask was it worth the extra £? 

My budget was around £2500 to start with, I then started looking at the TSA-120 and APM 115 LZOS (around double when the extras are included) expecting to see a significant improvement in image quality. I haven't costed a 106Q but I'm guessing it will be at least £6.5k with a flattener adapters - I could just buy it but if I survive longer than I'm expecting I might have no where to live :0

 Also, I'm really looking for a longer FL - be interesting to see some full frame images with stars as good as yours taken with a TSA-120. 

[pete_l]

It seems to me that telescope selection is much like choosing wine, or cars.
There are many and varied opinions. All subjective and all with different, unspoken, values put on various qualities of the product.
At least with telescopes we can see some samples before handing over the cash Even though there are very, very, few comparable images. Ones taken with the same camera, for the same exposure time, in the same conditions and with the same processing.

Ultimately, as with wine, people's choices seem to be defined more by the amount they are willing to spend than by any measure of objective "quality". Some have a consensus "good ... better ... best" rating - much of which correlates to price, in the absence of any definitive metrics. But few can say whether spending an extra £1000 gives you £1000-worth of better images.

I would say that the hardest part of the whole selection process is having that initial conversation with yourself: ultimately, what do you want:
Do you want nice images for your own fulfillment?  Do you want the pride of owning expensive stuff? Ease of use? Do you want the cachet of a recognised marque? An investment? A product that will last forever? Something that will do justice to the rest of your gear? All of the above or something entirely different?

Maybe have a look at what you drive and then buy the telescope that "that sort of person" would buy 😛

[Skipper Billy]

21 minutes ago, Midnight_lightning said:

Pretty much. I will look at each sub and say, could it be better? What could I do to make it better? But I will also ask was it worth the extra £? 

Fair enough - I have just looked up the price of the Esprit - it's MUCH cheaper than I thought it was and an absolute bargain I would suggest!

The Tak is about 6k but you wouldnt need any flatteners etc.

Its also worth bearing in mind that a skilled processor would turn out images form a budget scope on a budget mount with a budget camera and filters made from sweetie wrappers that would wipe the floor with my efforts from a reasonably specced outfit!

[Midnight_lightning]

12 minutes ago, pete_l said:

 

Maybe have a look at what you drive and then buy the telescope that "that sort of person" would buy 😛

Interesting idea but I buy a car for comfort. 

For astro equipment its all about the quality of the image, I dont care what it looks like or who's name is in it 😛

Just wondering if the issues I have seen in the images I have been reviewing are as much to do with how those setups were calibrated as the quality of scopes.  I guess  a lot of people, myself included, are not experts when it comes to tuning sets ups, adjusting tilt etc.

[Midnight_lightning]

13 minutes ago, Skipper Billy said:

Its also worth bearing in mind that a skilled processor would turn out images form a budget scope on a budget mount with a budget camera and filters made from sweetie wrappers that would wipe the floor with my efforts from a reasonably specced outfit!

That's a good point and something I was conscious of while reviewing images on Astrobin. Whilst a lot can be done in processing, and I am currently spending a lot of time learning PI (a benefit of the lockdown!), I still want the best raw ingredients I can produce

 

[ollypenrice]

If you want the best and largest flat field in your approximate budget, with the best controlled stars, buy a used TEC140 with dedicated TEC flattener. You'll also get an FT focuser and the best QC in the business into the bargain. Mine produces tighter stars, especially bright blue ones, than either of the Tak FSQ106 scopes I use here. Indeed much tighter. This is confirmed by a second TEC140 I also use here.

Let me be honest: I put the optics last in the imaging priority list. For me it's mount, camera, optics without any doubt whatever. Now you clearly have a supernaturally good HEQ5 if it's pulling an RMS of about  0.2. arcsecs. You cannot bank on that continuing with a heavier scope and and one with a longer moment. Nor can you bank on your outstanding HEQ5 marching on forever, so you might want to leave some budget for a mount upgrade. Be aware that you're leading a charmed life with that mount! 😁 My Mesus run at around 0.3 arcsecs but they've been doing so for years.

But what would I buy without pushing your initial parameters? An Esprit 120 from FLO.

Olly

[Skipper Billy]

35 minutes ago, Midnight_lightning said:

I still want the best raw ingredients I can produce

 

You do!  I have noticed that after I changed my budget scope for the Takahashi I do a LOT less in Pixinsight! 

[Big Bang!]

19 minutes ago, ollypenrice said:

But what would I buy without pushing your initial parameters? An Esprit 120 from FLO.

Olly

Absolutely spot-on.  On the basis of my experience and everything I have heard you say on here it's a no-brainer - buy the Esprit 120EDPro.  Compared to everything else I have seen it is by far the best value for money, even if it might not be quite in the Tak  or Tec class; that coupled to the flat field right into the corners and a 44mm imaging circle... Be realistic.

Gus