Skywatcher Esprit 100 ED

The main scope

The story before the Esprit

Actually I was quite satisfied with my TS 90/600 triplet apochromat. The triplet came along with a fibre reinforced carbon tube and a Baader Steeltrack Focuser. At the time I purchased the scope my only intension was to use it visual. Years later I still think that the scope was excellent for this application. It comes with a smooth working Focuser and delivers needle-sharp stars without noticeable chromatic aberration. All this weighs 3.5 kg only. Here I will give a description of the Skywatcher Esprit 100 ED, my way of setting work and the history how I came to it.

It took much effort to optimize the Flattener to chip distance. Finally I figured out that 119 mm is the best back focus. Since the original Flattener casing was a bit too loose I started my lathe and built a new one. The latter fitted inside the Steeltrack tube tight but without any tense. With the TS 2″ Flattener in its new casing the image train gave excellent star-images.

Constraints when used for astrophotography

TLAPO 906 carbon tube Avalon Linear
90 mm TS-Optics Triplet on the Avalon Linear.

More or less some disadvantages of this scope for photographic use led to the desire for something which fits better to my requirements. What are the photographic disadvantages?

The focal ratio is f/6.7 this is fast enough for many famous objects, but too slow for fainter objects or even narrowband imaging.

The Steeltrack is 2″ in diameter and it has no thread. It is designed for clamping equipment at the eyepiece side, only. In my opinion threaded connection of photographic equipment is to prefer. The diameter of 2 inches is large enough for APS-C size chips but too small for full format. Although the lens shall be full format capable the Focuser vignettes too much in that case. Hence the system is limited to APS-C, smaller or similar sizes.

Because of the Focuser the scope is only suited for some certain reducers. I tried the TS 0.79x reducer and the Tele Vue TRF-2008 which both are clamped 2 inch ones. The TS reducer gave good results and increased speed up to f/5.3. The price to pay for that was slightly larger star-images, I would say.

Definition of the successor

The successor should be a high quality refractor again or even better. The most important requirement is a fast focal ratio. Searching for suited scopes it reveals very fast that only a few types are in the closer choice. Most of them are really high priced. Someday an amateur known from astronomie.de offered his Skywatcher Esprit 100 ED in a package with the original Flattener and the small Riccardi reducer. I got the final impulse by the interesting thread at Cloudy Nights, which encouraged me in my opinion that the green Japanese scopes are not the only alternative.

Skywatcher Esprit 100 ED – MkI

Apperance of the Esprit 100ED in 2024.

The set-up description is slightly outdated. In the meantime a modified numerous details. As I think the information in this section might be helpful in some cases even with outdated configuration, I kept the section online as MkI. Find the MkII configuration at a separate page.

 

23 Gedanken zu „Skywatcher Esprit 100 ED“

  1. Hey Kai,
    zu aller erst einmal ein Lob für deine tolle Seite 🙂
    Ich baue mir gerade auch einen Esprit 100ED mit Riccardi Reducer zusammen, allerdings werde ich bei mir ein ESATTO3″ Focuser verwenden. Könntest du mir sagen, wie weit der der Backfocus in etwa vom „silbernen Steuerrad“ entfernt ist? Also der Abstand zwischen dem „silbernen Steuerrad“ und dem Sensor der Atik 383.
    Grüße
    Kevin

    Antworten

    1. Hallo Kevin,
      danke!
      Die Astrowelt ist doch ein Dorf. Ich schraube gerade an einem Newton Astrographen rum und hatte dafür auch mit dem ESATTO „geliebäugelt“. Habe mich aber dann doch für einen Moonlite entschieden.
      Zu Deiner Frage: Bei stimmt der Fokus ungefähr, wenn der Original-Fokussierer um 52mm ausgezogen ist. Dann liegen zwischen dem Captains Wheel und dem KAF der Atik ca. 237 mm.
      Viel Erfolg! Freue Dich schon mal auf die Kombination. Ich fast das Gefühl, dass der Esprit mit dem Riccardi besser abbildet als mit dem Orignal-Flattener…
      Gruss,
      Kai

      Antworten

      1. Hallo Kai,
        vielen Dank für deine Antwort und die Maßangabe, die wird mir meine Rechnereien sehr erleichtern.
        Da hast du recht, die Astrowelt ist wirklich ein Dorf 😀
        Nach anfänglichen Problemchen bin ich inzwischen sehr zufrieden mit dem ESATTO und freue mich schon auf den ARCO, welcher dann das Framing mit SGPro wesentlich ergonomischer machen dürfte.
        Ich freue mich schon wahnsinnig drauf. Von der Brennweite in etwa so, wie ich es von meinem 65Q gewohnt bin, nur halt eben die unschlagbaren f4.1 🙂
        Ich hoffe nur, dass bald noch die restlichen Teile kommen.
        Was ich so gelesen und an Tests gesehen habe, soll die Abbildung mit dem Riccardi wirklich besser sein als mit dem Original-Flattener. Solange die Qualität im Bereich meines 65Q liegt bin ich aber schon zufrieden 🙂
        Ich wünsche dir gutes Gelingen und gute Ergebnisse mit deinem Newton Astrographen 🙂
        Grüße
        Kevin

        Antworten

  2. Hi, i have rather two different questions:
    1. how do you find working Avalon linear with this tube? Im looking for experienced users opinions because im considering buying Avalon Linear for my WO98FLT scope @618mm, so would be nice if you have some thoughts about, lets say, some drawbacks, eg. sensitivity on wind etc…
    2. second is much simpler: i noticed nice, broad heater bands, are they available somewhere?
    clear skies!
    jarek

    Antworten

    1. Hi Jarek,

      regarding the Linear I’m still fully satisfied by this italien machine. It runs perfectly with the Esprit 100 ED and the guider. An important point for me: Last Saturday night I was out in the fields. It was quite windy, some cold blow from the east… I took 123 frames this night, 2 min each. The next morning I run the SubFrameSelector of Pixinsight and every frame had an eccentricity below 0.5, which means the probability that a frame is unusable due the the Linear is almost at 0%. I have the same experience taking 30min frames for narrowbanding!
      I had even a 8″ f/5 Newton with an off-axis guider running at the Linear. Even with this set-up I had no frame loss due to the Linear! For that reason I decided to build my own astrograph 12″ f/3.1. I’m sure that the Linear will even carry this load.
      I’m sorry, but the heater bands are DIY. I have desinged them in a way that they connect directly to my nominal voltage (13.8V) an heat with the desired power (1.5W for the Esprit and less for the finder). So I don’t need PWM electronics or others than plugs. – Everthing what can crack up will crack up sometimes… Hence I try to use simple equipment if possible.
      You will see strong wind at the guiding graph, but not significantly at the star FWHM. Once I had the system running during a really strong west wind, would say Beaufourt 3-4. This is difficult because my garden site is exposed to the west. In this case the FWHM was slightly increased, but much smaller than I expected with that guiding graph. I do not know how this behaves at 2m focal length, but with 500 – 600 this is not an issue at all.

      Clear sky and stay healthy,
      Kai

      Antworten

  3. Hi Kai

    This looks very interresting!
    Do you know if this would work with a 0.8 reducer as well?

    Also do you have any images to show with your Esprit and the reducer?

    Best regards,
    Mats

    Antworten

    1. Hi Mats,
      usually the result depends on the reducer. Some match good to some scopes and some other do not. You will never get a statement for a reducer ratio, only for a certain reducer model. I don’t expect any significant difference between 0.8 but 0.75 the question is: Does the reducer give a good companion for the Esprit?
      Cheers,
      Kai

      Antworten

  4. Hi Kai

    Do you have any images done with the 0.75x reducer on the Esprit 100ED?

    Also do you know if you can get a 0.8 reducer for it?

    Best regards,
    Mats

    Antworten

  5. Hello Kai,
    I would like to say how much I appreciated the very detailed information of the Esprit/Ricarrdi setup you have.
    I have just finished building this combination together with an SX mini EFW and ZWO 1600 MM Pro camera and Lakeside focuser. Your back focus distance of 78 mm is very accurate and I have perfectly round stars over the entire imaging field not to mention the perfect focal length for wide field imaging together with a very fast aperture for faint targets !
    Thank you Kai for sharing all this.
    Clear skies,
    Night watchman.

    Antworten

  6. Hi Kai
    This is Carlos.
    First of all, CONGRATULATIONS, you have really nice website and the best, you are really generous person because you are „sharing knowledge“ 😉
    GO TO THE MATTER
    I have just bought an ESPRIT ED100 and have too a ASI294.
    I am not sure how to connect the flattener to the ASI294.
    I use a IDAS LPS 2″ with M48 .
    I know that the configuration could be: Flattener + extender + IDAS LPS + ASI .TOTAL – (63 mm)
    But I am worry about the IDAS LPS, I am not sure if it can support the weight of the camera
    Could you please suggest me something???
    I do not Know if there is a „comercial solution“ or I have to manufacture something
    Thanks a lot.

    Antworten

    1. Thank you Carlos!
      Spain? Doesn’t really play a role, but it’s always interesting from where people contact me…
      Regarding the question I will send you an Email, but don’t expect a solution. I don’t have one ready..
      Regards,
      Kai

      Antworten

  7. Hi there,

    Nice write up! I own a SW Esprit 100ED and I am really interested in using the Riccardi Reducer. Are you still using it with your Esprit? If yes, would you say it is worth the investment?

    Going back your setup, would you be able to share a sketch of your image train, starting from the focuser of the Esprit 100ED. Like Erza, I am not clear how the Riccardi fit inside the drawtube so and sketch or picture would be very useful.

    My idea is to have a threaded adapter between the end of the focuser (M74x1) and the Riccardi (Same way how the original field flattener is attached to the focuser). Then, knowing the backfocus requirement of the Riccardi (78.5mm according to your test), I would have to get all the required adapters to attach an OAG, EFW and camera.

    Thanks in advance,
    Diego G
    Calgary, Canada

    Antworten

    1. Hi Diego,
      thanks! I reorganized my pages regarding the Riccardi adaption and added some information as well. I guess that there is now the information you missed. I addition I’ve sent you an Email..
      Cheers,
      Kai

      Antworten

  8. Hi,
    Can you elaborate more on the Riccardi reducer set-up you are using? I am not clear why you have the reducer inside of the draw tube. Also can you share where you had the adaptors made?

    Antworten

    1. Hi Ezra,
      it very simple, why the Riccardi is inside the draw-tube: If it would be outside, I would have to shorten the tube. Hope that helps?
      Adaptors I do not machine myself are ordered at Gerd Neumann. Mr. Neumann always does an excellent job. My absolute advice. The Riccardi adaptor came with the telecope. It was acquired by the previous owner. Sorry, but I don’t have any clue where he orderd that thing but is an accurate adaptor, as well.
      Cheers,
      Kai

      Antworten

  9. Hallo Kai,
    Verwendest du den kleinen oder den grossen Riccardi reducer/flattener in Kombination mit dem Sky-Watcher 100ED? Welchen würdest du empfehlen für eine Canon 80Da? Und für eine Vollformat Canon?
    Mit freundlichen Grüssen,
    Huub Willems
    Niederlande

    Antworten

    1. Hallo Huub,

      ich verwende „den Kleinen“, das ist der mit M63x1 Gewinde. Diesen habe ich auch mit einer EOS 5Da MkII erfolgreich eingesetzt. Das Vollformat wird dabei so gut ausgeleuchtet, dass eine Korrektur mit einem Flat problemlos möglich ist. Die stärksten Abschattungen/vignettierungen in dieser Anordnung kommen dann vom Spiegelkasten der DSLR. Dieses Bild wurde damit angefertigt. Die 80a ist eine tolle Kamera mit APS-C, damit kommt der kleine Riccardi hinsichtlich Ausleuchtung am ED100 locker zurecht. Ich habe dir noch eine Folie per Email gesendet.

      Gruss,
      Kai

      Antworten

  11. Hi Kai. My name is Roberto and I wrote to you from Spain. Recently I had bought an ESPRIT ED100 and it’s my first telescope with this features. I used previusly a little TS65 and a newtonian telescope and all the connections are easy but with the field flattener of the ESPRIT i’m a little confussed.
    I have a Canon EOS modified and with the TS65 I used an 2″ ir-cut filter screwed to a 2″ to M48 nose. I can’t use this set with the ESPRIT. Some people let me to buy a clip IDAS filter for my EOS but I read in your web that you used a custom rings to screw the filter. Do you recomend me this solution?
    In a few months I hope to get a CCD camera and I’m in doubt.
    Thanks a lot.

    Antworten

    1. Hi Roberto,
      best greeting to Spain!

      In the beginning I also tried to use my 5D MkII with an Astronomik EOS CLS-Clip-On Filter for full size chips. Using this Filter I attached the camera according to the operators manual using the standard parts delivered with the Esprit. The issue with this set-up is the vignetting of the full size Clip-On filters. Hence I decided to built an adapter for the filter drawer which enables me to use a 2″ filter. This drawer is not as solid as I would like to have it, but its just enough for my camera. This solution is really usable and produces good results. I do not intend to replace this set-up. I’m even thinking about to extend the solution for the use with my Riccardi. The drawing for the Adapter is already finished…

      I have no experience with the IDAS, but I assume the vignetting may be the same issue with all full size CLip-On filters. With the Astronomik it is not unacceptable in principle, but for me it was annoying and I didn’t like it.

      I can’t give you a recommendation. Even with my CCD I’m glad to have the choice between two cameras. The 5D gives me a large field even with 550mm focus length and the 383 better resolution and narrowband capabilities. Maybe the invest in the SLR image train won’t be wasted money.

      Cheers,
      Kai

      Antworten

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